Soil Fertility and Plant Nutrition for Sustainable Agriculture

Soil organic matter (SOM) quantity and quality are important factors that significantly influence soil fertility. SOM quality indicators change throughout time. In this study, long—term field experiments (22–50 years in duration) on a Cambisol at four sites in the Czech Republic were selected. Seven crops were successively rotated in the sequence: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were investigated, including an unfertilized treatment, farmyard manure, and various combinations of farmyard manure and mineral fertilization. A total of 40 t ha⁻¹ of farmyard manure was applied to the early potato and potato crops. Combining organic and mineral fertilizers increased soil organic matter quality and quantity over unfertilized or organic only treatment. The highest intensity of mineral fertilizers in our trials elevated the mean of carbon sequestration efficiency to 45.6% in comparison to pure manure treatment which reached only 22.9% efficiency. A strong correlation was established between the total glomalin content and soil organic matter carbon, fulvic acid, humic acid, carbon hot water extraction, potential wettability index (PWI), and aromaticity index. The PWI was also strongly correlated with these indicators. The E4/E6 ratio indicator was shown to be a much less sensitive method for reflecting the change in soil organic matter quality. Full article

Nitrogen reduction, in association with increased planting density and irrigation management, has been widely adopted in super rice cultivation systems to pursue higher yield with lower input. Here, soil microbial community structures under accurate N and water management were investigated after four years of experiments. Plot experiments were conducted with three treatments, including conventional farming practice (CF), reduced nitrogen with increased plant density (RNID), and reduced nitrogen with increased plant density and precise irrigation (RNIDPI). The results showed that RNID treatment increased soil bacterial diversity, enriched biomarker bacterial taxa, and altered bacterial community structure, with pH as the influential factor. The phylum Chloroflexi was enriched in the treatment of N reduction, while a higher ratio of Firmicutes was present in CF treatments. RNID treatment witnessed a low proportion of bacterial functional groups involved in nitrification and nitrate reduction. N fertilizer reduction with irrigation management increased rice yield (up to 22%) without changing the major soil fertility properties except for the increased pH and decreased ammonium N. The results suggest that N reduction, in association with increased plant density and accurate irrigation, is beneficial for super rice production. Full article

Glomalin, a glycoprotein secreted by arbuscular mycorrhizal fungi (AMFs), exhibits multiple beneficial functions in regard to plant growth. However, the roles and regulatory mechanisms of exogenous easily extractable glomalin-related soil protein (EE-GRSP) in water and their effects on the quality of tea plants (Camellia sinensis (L.) O. Ktze.) remain unclear. The present study aimed to investigate the effects of a quarter-strength exogenous EE-GRSP solution (1/4 EE-GRSP), half-strength exogenous EE-GRSP solution (1/2 EE-GRSP), three-quarter-strength exogenous EE-GRSP solution (3/4 EE-GRSP), and full-strength exogenous EE-GRSP solution (full EE-GRSP) on plant growth, the root system architecture, leaf water status, and the tea quality of tea seedlings, along with examining the changes in the relative expression of water channel proteins (AQPs) in tea plants. The results indicated that exogenous EE-GRSP of different strengths had different effects on both the growth performance (height, leaf numbers, and biomass) and root architecture parameters of tea seedlings, and the best positive effects on plant growth and the root architecture appeared under the three-quarter-strength exogenous EE-GRSP treatment. Similarly, the exogenous EE-GRSP application also differently affected tea quality indicators, in which only the quarter- and half-strength exogenous EE-GRSP solutions significantly increased most of the indicators, including carbohydrates, tea polyphenols, total amino acids, catechins, and flavonoids. Moreover, the half- and three-quarter-strength exogenous EE-GRSP treatments significantly increased the leaf relative water content (LRWC), but all of the exogenous EE-GRSP treatments significantly decreased the leaf water potential (LWP). Furthermore, the expression of AQP genes in the root system of tea plants was related to the strength of the exogenous EE-GRSP treatments, and different genes were significantly up-regulated or down-regulated under the treatment of exogenous EE-GRSP at different strengths. Moreover, the correlation analysis showed that most of the relative expression of AQPs was significantly and positively correlated with tea plant growth, the root architecture, and the leaf relative water content, but negatively correlated with tea quality indicators; however, the expression of CsNIPs and CsSIPs was markedly and negatively correlated with plant growth performance. Therefore, we speculated that the application of exogenous EE-GRSP could facilitate plant growth and improve the quality indirectly by regulating the expression of root AQPs, thus ameliorating the water uptake and nutrient accumulation in tea plants. Full article

Straw mulching on wet beds is an effective method to alleviate continuous cropping obstacles in greenhouses. However, this technique cannot be applied in the production of leafy vegetables with high planting density. Straw mulching in furrows is an alternative method in this circumstance. In this study, celery (Apium graveolens L.), a vegetable that prefers a high planting density and wet soil, was used to test furrow straw mulching technology, and the effect of different straw amounts and straw decomposers on soil improvement and celery production was investigated. The results showed that straw mulching in furrows significantly reduced soil conductivity and nitrate nitrogen levels, increased the contents of soil organic carbon as well as phosphorus and potassium nutrients in the bed, and improved celery yield and quality, indicating the significant lateral movement of released nutrients between the furrow and bed. The positive effects of 15,000 kg/ha straw application were more pronounced than those of 7500 kg/ha and 11,250 kg/ha. In addition, straw decomposers accelerated nutrient release and improved celery yield and quality. A decomposer named “ZhuBang” containing Bacillus licheniformis was the most effective. We concluded that furrow straw mulching combined with straw decomposer application is an effective measure for the sustainable production of leafy vegetables in intensive vegetable production facilities. Full article

Understanding a crop’s productive potential is crucial for optimizing resource use in agriculture, encouraging sustainable practices, and effectively planning planting and preservation efforts. Achieving precise and tailored management strategies is equally important. However, this task is particularly challenging in coffee cultivation due to the absence of accurate productivity maps for this crop. In this article, we created a multicriteria model to estimate the productive potential of coffee trees based on the observation of landscape elements that determine environmental fragility (EF). The model input parameters were slope and terrain shape data, slope flow power, and orbital image data (Landsat 8), allowing us to calculate the NDVI vegetation index. We applied the model developed to coffee trees planted in Bambuí, Minas Gerais, Brazil. We used seven plots to which we had access to yield data in a recent historical series. We compared the productivity levels predicted by the EF model and the historical productivity data of the coffee areas for the years 2016, 2018, and 2020. The model showed a high correlation between the calculated potential and the annual productivity. We noticed a strong correlation (R²) in the regression analyses conducted between the predicted productive potential and the actual productivity in 2018 and 2020 (0.91 and 0.93, respectively), although the correlation was somewhat weaker in 2016 (0.85). We conclude that our model could satisfactorily estimate the yearly production potential under a zero-harvest system in the study area. Full article

Understanding the spatial–temporal variability of soil enzymatic activity and its relationship with nitrogen (N) resources in the soil and crop yield is crucial in rational management practices of mineral fertilization. The scarcity of comprehensive studies on geostatic analyses of agricultural soils and plant yields, which would take into account both temporal and spatial variability, was the reason for undertaking this research. The aim of this study was to determine the spatial and temporal variability of the activity of soil enzymes, such as acid (PAC) and alkaline (PAL) phosphatases, urease (URE) and protease (PROT), the content of N-NH₄ (ammonium ions), N-NO₃ (nitrate ions), phosphorus (P), pH, moisture, as well as crop yield on a conventionally managed farmland of 40 ha. During the two-year experiment, soil samples were collected from 37 measurement points. Wheat was the first tested crop, followed by oilseed rape. It was shown that all the tested soil parameters showed temporal and spatial variability, and a significant number of them were significantly higher in July. The creation of raster maps showing the distribution of the tested parameters allowed for the observation of the considerable activity of PAC, PAL, URE, and PROT, as well as a high application of N-NO₃ in the southern part of the field during the growth of the plants. The statistical analysis revealed a negative interaction between the N-NH₄ and N-NO₃ and the urease in the soil under the cultivation of plants. The pH and the percentage of moisture in the soil also had higher values in the south of the field. This pointed to the existence of separate production zones in the south-central part of the field, characterized by a higher yield of wheat and rape. On the basis of the conducted research, it was unequivocally stated that the values of enzymatic and chemical parameters of the soil were reflected in the size of the yield obtained, which allows conclusions to be drawn with respect to the rational management of N in the production process, laying the foundations for precision agriculture. Full article

The addition of biochar-based organic fertilizer (BOF) can improve sugar beet yield, but its effects on the growth of sugar beet and on soil quality at different densities remain unclear. Six treatments, comprising two densities D1 and D2 (80,000 and 90,000 plant ha⁻¹) and three application rates B1, B2, and B3 (2.75, 3.25, and 3.75 t ha⁻¹) of BOFs + mineral fertilizer, respectively, are investigated in this research. The mineral fertilizers are typically used to supplement the total N, P₂O₅, and K₂O deficiencies. The BOFs were used in the soil before sowing, and the mineral fertilizer was added to the soil after the first pair of true leaves was grown. At 160 days after sowing (DAS), the root-to-shoot ratio under the D2B2 treatment was significantly higher than that under the other treatments. The effect of density on the photosynthesis rate of sugar beet was not significant. The BOF application amount and density exerted interaction effects on soil physicochemical properties and the activities of different soil enzymes affecting each other. Both the D2B2 and D2B3 treatments reduced the content of NO₃^–-N in the 40–60 cm soil layer. Combined 90,000 plants ha^–1 with 3.25 t ha⁻¹ BOFs can increase the soil nutrient content of the 0–60 cm soil layer, improve the rhizosphere soil environment, promote the uniform distribution of dry matter, and increase sugar production. Full article

Inoculants containing strains of bacteria that fix atmospheric N that are tolerant or resistant to chemical products commonly used in seed treatment are classified as long-life inoculants, which contribute to improving the efficiency of nodulating bacteria in soybean crops. The objective of this work was to evaluate the effects of applying commonly used pesticides in seed treatment and a long-life inoculant, alone or in combination, on the nodulation process and seed quality of soybeans during storage. The first experiment was carried out in a greenhouse using a completely randomized design, in an 8 × 2 factorial arrangement, with three replications. The treatments consisted of applications of industrial seed treatments: control, MaximAdvanced, Fortenza, long-life inoculant, MaximAdvanced + Fortenza, MaximAdvanced + long-life inoculant, Fortenza + long-life inoculant, and MaximAdvanced + Fortenza + long-life inoculant. The seeds were sown in pots containing soils from two crop areas. The second experiment was carried out in a laboratory, using a completely randomized design in an 8 × 7 factorial arrangement, with four replications. The treatments consisted of the same eight treatments used in the greenhouse experiment, which were applied before packaging and storing the seeds for two months. The industrial seed treatment with the mixture of fungicide, insecticide, and inoculants improved the soybean photosynthesis and nodulation processes, regardless of the history of the area. Soybean seeds can be stored for commercial purposes for up to 40 days, regardless of the seed treatment with fungicide, insecticide, and long-life inoculant applied alone or in combination. Full article

Saline soils negatively affect and cause serious problems for rice cultivation. This study aimed to evaluate the efficacy of the purple nonsulfur bacteria (PNSB) capable of secreting 5-aminolevulinic acid (ALA) to reduce soil salinity, improve soil fertility, and enhance rice growth and yield. A two-factorial experiment was conducted in a randomized complete block design with four replications. Factor one was the salinity of the irrigated water, and factor two was the supplementation of the ALA-producing PNSB. The results indicated that watering with saline water above 3‰ led to decreases in plant growth and rice yield compared to the treatments watered with tap water. Application of either an individual strain or the mixture of W01, W14, and W22 ameliorated soil properties and increased total NPK uptake, whereas treatments supplied with the mixed strains reduced total Na uptake (9.50 mg Na pot⁻¹). Supplying the W01, W14, and W22 strains individually or in a mixture enhanced the plant height by 3.51–5.45% and rice grain yield by 14.7–26.2%, compared with those of the control treatment. From the study, the combination of the L. sphaeroides W01, W14, and W22 strains is promising for application in saline or salt-contaminated regions to aid the damages caused by salinity on cultivars there, especially rice. Furthermore, this is a biological approach to ease an environmental problem and improve crop performance, which is supposed to be a trend in the sustainable agriculture. Full article

The problem of phosphorus and nitrogen deficiency in agricultural soils has been solved by adding chemical fertilizers. However, their excessive use and their accumulation have only contributed to environmental contamination. Given the high content of nutrients in biosolids collected from a food industry waste treatment plant, their use as fertilizers was investigated in Zea mays plants grown in sandy loam soil collected from a semi-desert area. These biosolids contained insoluble phosphorus sources; therefore, given the ability of Azotobacter nigricans to solubilize phosphates, this strain was incorporated into the study. In vitro, the suitable conditions for the growth of Z. mays plants were determined by using biosolids as a fertilizer and A. nigricans as a plant-growth-promoting microorganism; in vitro, the ability of A. nigricans to solubilize phosphates, fix nitrogen, and produce indole acetic acid, a phytohormone that promotes root formation, was also evaluated. At the greenhouse stage, the Z. mays plants fertilized with biosolids at concentrations of 15 and 20% (v/w) and inoculated with A. nigricans favored the development of bending strength plants, which was observed on the increased stem diameter (>13.5% compared with the negative control and >7.4% compared with the positive control), as well as a better absorption of phosphorus and nitrogen, the concentration of which increased up to 62.8% when compared with that in the control treatments. The interactions between plants and A. nigricans were observed via scanning electron microscopy. The application of biosolids and A. nigricans in Z. mays plants grown in greenhouses presented better development than when Z. mays plants were treated with a chemical fertilizer. The enhanced plant growth was attributed to the increase in root surface area. Full article

Swine manure is widely used for ameliorating red soil acidification, but little information is available about its effect on N₂O emissions. To explore the effects, a 35-day incubation experiment was conducted with two soils under different fertilization history: chemical fertilizers only (F) and combination of chemical fertilizers with swine manure (M). The treatments included no fertilizer (control), 100% N from urea (M0), and urea plus swine manure, which supplied 20% (M20), 40% (M40), 60% (M60), and 100% (M100) of total N. Soil N₂O emission rates, pH, exchangeable acidity, mineral N species, dissolved organic carbon and nitrogen, microbial biomass carbon, and their inner relationships were examined. The N₂O emission rates markedly increased following the treatments, reached peaks before day 2, and thereafter decreased sharply to the level of the control by day 25, 25, 23, 15, and 9 in F soil and by day 25, 25, 23, 19, and 11 in M soil for M0, M20, M40, M60, and M100 treatments, respectively. As swine manure application rate increased, the cumulative N₂O emissions of F soil decreased significantly, while, for M soil, there was no significant difference among M0, M20, M40, and M60 treatments, which were higher than the M100 treatment. At the end of incubation, soil pH in F and M soils followed the order M0 < M20 < M40 < M60 < control < M100 and vice versa for exchangeable Al³⁺ and acidity. F soil had relatively higher NH₄⁺-N concentration in M0 treatment and higher NO₃⁻-N concentrations in M0 and M20 treatments than M soil. Soil pH and NH₄⁺-N had the greatest relative contribution to N₂O emissions. Overall, this study indicates that partial chemical N replacement by swine manure could effectively mitigate N₂O emissions from acidic red soil primarily because of mineral N immobilization and alleviated red soil acidification. Thus, swine manure has the potential to co-ameliorate red soil acidification and N₂O emission. Further research is needed to determine the effect of swine manure on N₂O emission reductions under field conditions and the overall benefit in effective N management. Full article

The current study aimed to improve the nitrogen recovery efficiency (NRE) of maize under the application of balanced proportions of ammoniacal-nitrogen (NH₄⁺-N) and nitrate-nitrogen (NO₃⁻-N) (1:1), as well as to determine economic impacts of such fertilizers on maize productivity. A 3-year field study was carried out in Sahiwal, Punjab, Pakistan during the 2018–2020 growing seasons with autumn maize. In parallel, multi-location field experiments were conducted at farmer’s fields in Sahiwal during the same growing seasons with autumn maize. The trials compared the effects of different fertilizers like urea, calcium ammonium nitrate (CAN), Sarsabz nitrophos (NP), nitrphos plus (NP Plus), and di-ammonium phosphate (DAP) on maize growth and yield, as well their economic efficiency. The results revealed that the application of Sarsabz NP and CAN increased the maize grain yield by 30%, 13%, 15%, 19%, 15%, and 9% as compared to the control, NP + urea, NP Plus + CAN, NP Plus + urea, DAP + urea, and DAP + CAN, respectively. In addition, the combined application of NP and CAN increased the total N and NO₃⁻-N concentrations, whereas it decreased the NH₄⁺-N concentrations in the soils. By contrast, NP + CAN increased the NH₄⁺-N concentrations in maize leaves as compared to NO₃⁻-N concentrations. Overall, the NRE of maize plants and the net return were higher under combined application of NP and CAN. In conclusion, CAN fertilizer increased the soil NO₃⁻-N concentrations, which thus assimilated in the plants as NH₄⁺ and improved the NRE of maize. Improved NRE thus enhanced maize yield and resulted in the maximum net return as compared to all other fertilizer combinations. Full article

Balanced nutrients are essential for healthy plant growth, but there is no sensor available to monitor essential nutrients such as N and K. Electrical conductivity (EC) is one of the key parameters that could be adopted to monitor nutrient contents because soil EC is influenced by the available nutrients. Therefore, the main objective of this study was to examine the effects of different basal fertilizers, including inorganic, organic, and compost fertilizers, and the application ratio of basal and additional fertilizers on nutrient contents with an EC sensor. The applied basal and additional fertilizer ratios were N 30:70, K 40:60, and N 20:80, K 20:80, respectively, for each fertilizer treatment. The results showed that the EC sensor value was positively associated with water content. The soil EC response increased with inorganic fertilizer and fertigation, and it was positively correlated with soluble nutrients and exchangeable ammonium. The correlation coefficients between sensor EC and soluble nutrients, nitrate, and ammonium nitrogen were 0.87, 0.86, and 0.65, respectively. The principal component analysis (PCA) also elucidated that inorganic fertilizer was positively associated with sensor EC, soluble Na, Ca, Mg, and nitrate among variables. This work suggests that soil available nutrients, especially N, could be monitored with an EC sensor, and the soil nutrient status could be regulated to promote better plant growth. Full article

Soil proteinase and proteinase-producing microbial community are closely associated with soil fertility and soil health. Sea rice has been planted in the coastal beach of Jiaozhou Bay, China, in an effort to transform saline-alkali soil into arable land. However, the knowledge regarding the bacterial degradation of organic nitrogen in sea rice soils is limited. This study aims to investigate the physicochemical characteristics and enzymatic activities of the sea rice soils, as well as the microbial communities by both the Illumina sequencing-based culture-independent technology and culture-dependent methods. Sea rice soils exhibited a lower salinity and higher organic matter content and proteinase activity, as well as an increase in both the richness and diversity of the proteinase-producing bacterial community, compared to the adjacent non-rice soils. The Proteobacteria phylum and the Gammaproteobacteria class were dominant in sea rice soils, showing higher abundance than in the reference soils. The Planococcus genus and Bacillus-like bacterial communities were abundant in the cultivable proteinase-producing bacteria isolated from sea rice soils. Furthermore, a significant proportion of the extracellular proteinase produced by the isolated soil bacteria consisted of serine proteinases and metalloproteinases. These findings provided new insights into the degradation of soil organic nitrogen in coastal agricultural regions. Full article

Reliable fertilizer recommendations should account for factors influencing nutrient supply, including non-exchangeable potassium (K) reserves and fixation capacity, to ensure optimum crop yields. The combined effects of non-exchangeable K reserves and fixation capacity of soils on crop response to K application has not been evaluated. This study evaluated the response of sugarcane yields to K application on two soils with contrasting combinations of non-exchangeable K reserves and fixation capacity. Potassium was applied at 0, 120, and 240 kg K ha⁻¹ at the commencement of the field trials and after each harvest on an umbric Acrisol, which had low non-exchangeable K reserves and medium K fixation capacity, and a cutanic Acrisol, which had ‘very high’ non-exchangeable K reserves and fixation capacity. Sugarcane stalk and sucrose yield, leaf, and exchangeable K were measured for each season. In the umbric Acrisol, a lower sucrose yield was measured in the 240 kg K ha⁻¹ treatment compared to the control for the plant crop, but this application rate had higher yields for the second ratoon. In contrast, there was no yield response to K application in cutanic Acrisol. This study indicated the importance of non-exchangeable K reserves and fixation capacity when calculating K requirements and conducting field calibration studies. Full article

Maize is one of the most important cereals in the world. It is a crop demanding in nitrogen. Therefore, alternative sources of fertilization bring agronomic, environmental and economic benefits. The objective of this study was to evaluate the biomass and productivity of maize fertigated with wastewater from swine and fish farming in different dilutions. The soil used is classified as Dystroferric Red Latosol, Cerrado phase, with clayey texture. The experimental design used was randomized blocks in 2 × 4 split plots with three replications. The treatments consisted of two sources of wastewater (fish farming and swine farming) diluted with the recommended dose of wastewater + 0, 25, 50 and 75% of its volume in water. The accumulation of dry mass (leaf, stalk and aerial parts) was evaluated at 30, 60, 90 and 110 days after sowing. The evaluation of yield variables (number of grain rows, number of grains per row, grain sizes, grain dry weight, gran yield and harvest index) occurred at 130 days after sowing. The largest accumulation of dry biomass at the end of the maize cycle and evaluated productivity variables were obtained with the application of swine farming wastewater. Wastewater from fish farming applied via an irrigation system without dilution (0%) is the most suitable for obtaining the productivity of corn grains. The two sources of wastewater have the potential to partially replace mineral nitrogen fertilizer in maize. Full article

Excessive application of nitrogen fertilizer during rice cultivation leads to progressive soil contamination in the long term and increases production costs. An alternative to reduce over fertilization is to partially replace the fertilizer with microbes that promote nutrition and growth, such as arbuscular mycorrhizal fungi (AMF). We investigated the combination of four different rates of AMF (M): (M₀: 0 g polybag⁻¹, M₁: 15 g polybag⁻¹, M₂: 30 g polybag⁻¹, and M₃: 45 g polybag⁻¹) and three rates of nitrogen (N) fertilizer: (N₀: 0 kg N ha⁻¹, N₁: 90 kg N ha⁻¹, N₂: 180 kg N ha⁻¹) on Trisakti rice cultivar cultivated in polybag. Our findings indicate that the combination of 45 g AMF polybag⁻¹ and 180 kg N ha⁻¹ decreased soil bulk density by 38.02% and 37.24%, increased soil pH by 14.81% and 14.95%, soil porosity by 60.68% and 61.09%, soil organic matter by 28.62% and 30.46%, total N by 92.59% and 89.66%, available phosphorus by 30.12% and 29.85%, available potassium by 3.75% and 4.01%, rice plant height by 19.19% and 19.79%, tiller number by 25.27% and 26.08%, SPAD by 20.71% and 20.62%, flag leaf area by 107.76% and 108.02%, panicle length by 49.72% and 52.31%, panicle number by 67.44% and 72.35%, 1000-grain weight by 30.70% and 32.44%, root dry matter by 54.34% and 53.69%, shoot dry matter by 26.08% and 28.26%, root length by 54.68% and 56.44%, root volume by 42.73% and 43.37%, and N uptake by 107.93% and 108.06% compared to control during the early and late seasons, respectively. Conclusively, the combined application of AMF and N fertilizer increased the physiochemical properties, rice growth, rice productivity, and N uptake compared to AMF alone, N fertilizer alone, and the control treatment. Full article

Enhanced suberin1 (ESB1) is a protein whose mutation is correlated with an increase in root suberin and altered nutrient concentrations. Here, we show a physiological and histological characterization of esb1 mutant plants of Brassica rapa L. Therefore, the potential use of this mutant in selenium (Se) biofortification and/or cadmium (Cd) phytoremediation programs was also evaluated by applying 20 μM of Na₂SeO₄ and 0.49 μM of CdCl₂ to a nutrient solution. With respect to wild type (WT) plants, an increase in root suberin was observed in esb1 at the level of the exodermis. This increase in root suberin did not affect photosynthesis performance. However, the esb1 mutant showed an increase in transpiration rate and a decrease in water use efficiency. Additionally, root histological changes affected the transport and concentration of some mineral elements. Thus, our results suggest that esb1 mutants of B. rapa would not be useful for Se biofortification because no significant differences were observed between the two genotypes at the leaf level. Nevertheless, the esb1 mutant reduced Cd translocation to the leaves and increased Fe and Cu uptake, so ESB1 mutation could be useful for Cd phytoremediation and Fe and Cu biofortification, although further research is needed. Therefore, this study provides detailed information on the effect of ESB1 mutation in B. rapa and suggests its potential use in biofortification and phytoremediation programs. Full article

China’s field crops such as cotton, wheat, and tomato have been produced on a large scale, but their cultivation process still adopts more traditional manual fertilization methods, which makes the use of chemical fertilizers in China high and causes waste of fertilizer resources and ecological environmental damage. To address the above problems, a hybrid optimization of genetic algorithms and particle swarm optimization (GA–PSO) is used to optimize the initial weights of the backpropagation (BP) neural network, and a hybrid optimization-based BP neural network PID controller is designed to realize the accurate control of fertilizer flow in the integrated water and fertilizer precision fertilization control system for field crops. At the same time, the STM32 microcontroller-based precision fertilizer application control system for integrated water and fertilizer application of large field crops was developed and the performance of the controller was verified experimentally. The results show that the controller has an average maximum overshoot of 5.1% and an average adjustment time of 68.99 s, which is better than the PID and PID control algorithms based on BP neural network (BP–PID) controllers; among them, the hybrid optimization of PID control algorithm based on BP neural network by particle swarm optimization and genetic algorithm(GA–PSO–BP–PID) controller has the best-integrated control performance when the fertilizer application flow rate is 0.6m³/h. Full article

This study aimed to determine the effect of irrigation amount ($W$), nitrogen ($N$), potassium ($K$), and zinc ($Zn$) on the net photosynthetic rate ($Pn$) of closely planted apple trees on dwarf rootstocks in arid areas of Xinjiang. Taking the “Royal Gala” apple as the experimental material, a mathematical model for $Pn$ was established using the principle of four-factor five-level quadratic regression with a general rotation combination design. The results show that: (1) The regression equations reached significant levels (F = 37.06 > F_0.01(11.11) = 4.54). (2) The effect of $W$, $N$, $K$, $Zn$ on $Pn$ is significant with relative importance $W$ > $N$ > $Zn$ > $K$. (3) The results of single factor analysis showed that with an increase in W, N, K, and Zn, $Pn$ exhibits an n-shaped parabolic response. (4) The positive coupling between $W$ and $N$ is significant, and the positive coupling between $W$ and $Zn$ is also significant. (5) Analysis of the interaction between sets of three factors revealed that $W$, $N,$ and $Zn$ could be combined to best effect, with the maximum value reaching 12.77 $\mathsf{\mu }\mathrm{mol}·{\mathrm{m}}^{-2}·{\mathrm{s}}^{-1}$. Compared with $W\times K\times Zn$ and $W\times N\times K$, the combination of $W\times N\times Zn$ reduces $W$ by 9.2% and 6.3%, respectively, which indicates its suitability for use in the dry and water deficient planting environment in Xinjiang. (6) Within the 95% confidence level, when $W$ is 258–294.75 mm, $N$ is 33.44–39.51 $\mathrm{kg}/{\mathrm{hm}}^2$, $K$ is 53.82–69.39 $\mathrm{kg}/{\mathrm{hm}}^2,$ and $Zn$ is 6.46–7.84 $\mathrm{kg}/{\mathrm{hm}}^2$, the net photosynthetic rate reaches 11 $\mathsf{\mu }\mathrm{mol}·{\mathrm{m}}^{-2}·{\mathrm{s}}^{-1}$. Full article

The commercial production of poinsettias begins with the propagation of apical cuttings from stock plants. The aim of the study was to use bacterial mixtures prepared with PGPRs in the cultivation of stock mother poinsettia plants and determine an effective IBA dose to increase root development and root yield of cuttings prepared from these stock mother plants. Rooted cuttings of Euphorbia pulcherrima Willd.ex Klotzsch were used for planting stocks of mother plants. Eight different bacterial isolates were mixed in triple combinations to form 4 different bacterial formulations: (BI) formulation 1 (Paenibacillus polymyxa TV-12E + Pseudomonas putida TV-42A + Pantoea agglomerans RK-79); (BII) formulation 2 (Bacillus megaterium TV-91C + Pantoea agglomerans RK-92 + Bacillus subtilis TV-17C); (BIII) formulation 3 (Bacillus megaterium TV-91C + Pantoea agglomerans RK-92 + Kluyvera cryocrescens TV-113C); and (BIV) formulation 4 (Bacillus megaterium TV-91C + Pantoea agglomerans RK-79 + Bacillus megaterium TV-6D). In the first year, rooted cuttings of stock mother plants were dipped in liquid microbial solution (bacterial formulations) for 15 min and then planted in plastic pots. In the second year, the same bacterial formulations were freshly prepared and applied to the 1-year-old stock mother plants as irrigation water for the second time. Amounts of 0 (control), 1000, 1500, and 2000 mg L⁻¹ IBA doses were used for rooting cuttings taken from the 2-year-old stock mother plants. In the experimental group treated with the BI bacterial formulation, the number of rooted cuttings (NR) increased by 14.26% and 19.00%, compared with the control, in response to IBA 1500 mg L⁻¹ and IBA 2000 mg L⁻¹ treatment, respectively. Compared to the mean root length of the cuttings in the control treatment, the mean root length of the cuttings in the BIV treatment increased by 18.83%. The mean root length values decreased with the increase in IBA doses. The highest value of the number of mean shoots (NAS) was in cuttings treated with BI + 1500 treatment, which was 1.93 times higher than the control. The highest nitrogen content (5.73%) was determined in the bract leaf samples of the BIV application, and an 81.33% nitrogen increase was detected in the related application when compared to the control. In terms of P, Ca, and Fe contents, higher values were obtained from the BIV application when compared to the control application. The highest values of K content were determined in BIII and BII applications. This study provides positive effects on the feedback of stock mother plants with PGPR to provide sprout production by cuttings technique. It has been revealed that lower IBA dose applications can be recommended for rooting cuttings taken from mother plants treated with the BIV bacterial formulation. Full article

Background: Micronutrient malnutrition affects millions of people due to a lack of Zn and Se. Methods: The process conditions for the manufacture of glycine−chelated sodium selenite (Se−Gly) and zinc sulfate heptahydrate (Zn−Gly) were studied. The effects of ligand concentration, pH, reaction ratio, reaction temperature, and reaction time on fertilizer stability were assessed. The effects of Zn−Gly and Se−Gly on tea plants were determined. Results: Orthogonal experiments showed that the optimal preparation conditions for Zn−Gly (75.80 % Zn chelation rate) were pH 6.0, ligand concentration 4 %, reaction ratio 1:2, reaction time 120 min, reaction temperature 70 ℃. The optimal preparation conditions for Se−Gly (56.75 % Se chelation rate) were pH 6.0, ligand concentration 10%, reaction ratio 2:1, reaction time 40 min, temperature 50 ℃. Each chelate was completely soluble in water and verified by infrared spectroscopy and ultraviolet spectroscopy. Conclusions: Zn−Gly and Se−Gly increased the Zn and Se content in tea plants, and foliar application was more effective than soil application. Combined application of Zn−Gly and Se−Gly was more effective than Zn−Gly or Se−Gly alone. Our findings suggest that Zn−Gly and Se−Gly provide a convenient method of addressing human Zn and Se deficiency. Full article

Nitrogen (N) is the nutrient most taken up by potato and cassava crops and Azospirillum brasilense may contribute to the growth of these crops. Pot experiments evaluated A. brasilense and mineral N application on leaf N concentration, plant growth, and N uptake by potato and cassava grown under natural and disinfected soil. The rates of 2.8 × 10⁸ colony-forming units mL⁻¹ of A. brasilense combined with 0, 75, 150, and 300 mg dm⁻³ N or 0, 50, 100, and 200 mg dm⁻³ N were used for potato or cassava grown. At low N supply in natural soil, A. brasilense inoculation increased N concentration in potato leaves by 23–38%, without benefits to plant growth or N uptake. At unfertilized N treatments of both soils, A. brasilense inoculation increased cassava leaf N concentration by 25–33%, but an 11–32% increase in shoot biomass occurred in treatments inoculated and N supplied. Potato crops responded positively to mineral N supply, but cassava responded to fertilization only in disinfected soil. In disinfected soil fertilized with N, A. brasilense inoculation increased cassava N uptake by 27–40%. In contrast, in natural soil, A. brasilense minimized the negative effect of N excess on the tuber development of cassava. These results show that the use of A. brasilense is a more interesting alternative to improve N status and growth in cassava than in potatoes. Full article

A plant factory is a highly developed product system that can produce higher yields and better quality plants under controlled conditions. However, knowledge of blueberry cultivation in plant factories is limited. This study established an advanced plant factory with artificial lighting (PFAL) and investigated the effects of nutrition supply and light qualities on the growth performance of blueberries. Different nutrition treatments affected the vegetative growth of blueberries in PFAL, especially the new shoot length and number. Exogenous fertilization significantly promoted the uptake of N, P, and K elements, and a nutrition solution with N:P:K = 2:1:1 was suggested to be superior for blueberries in PFAL. Red light facilitated vegetative growth to some degree, and the blue light was conducive to increased chlorophyll and anthocyanin content. The Pn value was significantly enhanced under 60% red plus 40% blue light. Combining red and blue light is more beneficial to blueberry growth and might be a preferential strategy in PFAL. This study is the first to investigate the growth performance of blueberries cultivated in PFAL, which can provide an important theoretical database for blueberry cultivation in a plant factory with artificial lighting. Full article

Soil organic carbon (SOC), an important indicator to evaluate soil fertility, is essential in agricultural production. The traditional methods of measuring SOC are time-consuming and expensive, and it is difficult for these methods to achieve large area measurements in a short time. Hyperspectral technology has obvious advantages in soil information analysis because of its high efficiency, convenience and non-polluting characteristics, which provides a new way to achieve large-scale and rapid SOC monitoring. The traditional mathematical transformation of spectral data in previous studies does not sufficiently reveal the correlation between the spectral data and SOC. To improve this issue, we combine the traditional method with the continuous wavelet transform (CWT) for spectral data processing. In addition, the feature bands are screened with the successive projection algorithm (SPA), and four machine learning algorithms are used to construct the SOC content estimation model. After the spectral data is processed by CWT, the sensitivity of the spectrum to the SOC content and the correlation between the spectrum and the SOC content can be significantly improved (p < 0.001). SPA was used to compress the spectral data at multiple decomposition scales, greatly reducing the number of bands containing covariance and enabling faster screening of the characteristic bands. The support vector machine regression (SVMR) model of CWT-R′ gave the best prediction, with the coefficients of determination (R²) and the root mean square error (RMSE) being 0.684 and 1.059 g∙kg⁻¹, respectively, and relative analysis error (RPD) value of 1.797 for its validation set. The combination of CWT and SPA can uncover weak signals in the spectral data and remove redundant bands with covariance in the spectral data, thus realizing the screening of characteristic bands and the fast and stable estimation of the SOC content. Full article

Peanut (Arachis hypogaea L.) is one of the most important crops produced worldwide. Peanut is the dominant crop in the typical upland red soil areas of China; however, phosphorus bioavailability in red soil is very low, which severely affects peanut production. To improve the phosphorus bioavailability, which substantially promotes the green development of peanut production, a peanut–green manure rotation field experiment was conducted with six treatments (milkvetch; radish; brassica rape; mustard rape; winter fallow and no-tillage), commencing in September 2017 in the red soil area of Jiangxi province, China. The results show that compared with no-tillage (NT) treatments, different green manure returning treatments had significant effects on soil pH, soil phosphorus components and available potassium content. The particulate phosphorus and soil available phosphorus contents in the green manure treatments were significantly higher than those in the winter fallow (WF) treatment. Compared with the WF treatment, the content of particulate phosphorous in brassica rape (BR), radish (R) and milkvetch (MV) treatments was significantly increased by 6.55%, 3.66% and 2.50%, respectively; the available phosphorus content in mustard rape (MR), BR, R and MV was significantly increased by 20.93%, 25.60%, 23.76% and 18.10%, respectively. In addition, the total phosphorus content of peanut shell in the MV and R treatment was significantly higher than that in the WF treatment, increasing by 33.47% and 60.66%, respectively. Compared with the WF treatment, the peanut biomass of MR, BR and R treatments increased significantly by 19.51%, 29.83% and 19.77%, respectively. The total phosphorus accumulation in all green manure treatments was higher than that in the WF treatment, and the MV treatment reached a significant level at 18.83%. Based on these results, the particulate phosphorus (PP) and available phosphorus were significantly affected by different green manure treatments; green manure amendment improves peanut phosphorus uptake. The use of green manure (especially milkvetch and brassica rape) can be recommended to improve phosphorus bioavailability and yield of peanut in red soil areas. Full article

Enhancing cereal crop production to feed the largely growing population is an important approach towards maintaining food security. Fertilizer management is the major component of crop production requiring special attention for sustainable application. Integrated nutrient management (INM) is an evolving idea, which appears to contribute to sustainable nutrient management. A field study was designed to see the impact of INM on a maize–wheat cropping system during winter (wheat) and summer (maize) season at Agronomic Research Farm, Bahauddin Zakariya University Multan, Pakistan. Both wheat and maize crops were grown consecutively along with full inorganic fertilizer (NPK) as well as with partial dose of fertilizer (25%, 50%, 75% NPK) supplemented with or without the addition of biochar (5 ton/ha). Data were collected regarding crop growth, yield and quality and further analyzed using MSTAT-C statistics software. Results revealed that the INM approach (75% of NPK + Biochar) enabled crops to improve dry matter production and its translocation towards sink which in turn boosted the crop productivity. This treatment improved dry matter (19%, 57%), grain weight (44%, 54%), grain yield (60%, 63%) and harvest index (30%, 29%) over the control in maize and wheat crops. It also improved the nutrient uptake in the plants which in turn improved the nutrient contents in the grains. Similarly, crops recorded higher system productivity (USD 790, USD 830) in both years and were found to be economically sustainable under INM. It was concluded that an INM strategy (75% of NPK + Biochar) can improve the productivity and sustainability of a maize–wheat cropping system to maintain the food security. Full article

In the context of intensive and sustainable agriculture, limiting soil degradation and the loss of organic matter has become an obligation to maintain food security. The use of organo-mineral fertilizer (OMF) products is an innovative technology that may solve the different challenges raised. This study aimed to evaluate the effect of various organo-mineral fertilizer (OMF) formulations on Zea mays agro-physiological traits, phosphorus (P)-related parameters, and water conservation during a 90-day pot experiment. The OMF formulations consisted of blending several doses of a stable OMWS compost (10 t /ha(OMF1), 50 t/ha (OMF2), or 100 t/ha (OMF3)) with different sources of mineral P, namely diammonium phosphate (DAP), rock phosphate (RP), or phosphate washing sludge (PWS), compared with separate applications. The results indicated that the effect of an OMF on the soil and plants was strongly dependent on the source of P used and the dose of OMWS compost. The best agronomic performance was attributed to OMF1-based DAP, which resulted in a significant improvement in the shoot and root biomass dry weight by more than 260% and 40%, respectively. However, using an OMF2 formulation was more optimal when using RP and PWS as mineral P sources. Independently of the type of P fertilizer, the addition of stable OM systematically improved multiple soil properties, including water availability, and the nutrient concentrations, such as the available P, exchangeable potassium, and magnesium. Furthermore, the plant’s respiration, photosynthetic activity, and nutrient assimilations were positively affected by the OMF formulations. Overall, our results demonstrate that organo-mineral fertilization is a promising solution for increasing the efficiency of low-P and high-P mineral fertilizers in alkaline soils through direct and indirect mechanisms involving improved soil properties and higher P solubilization. Full article

Foxtail millet (Setaria italica L.) is one of the most economically valuable drought-resistant crops in arid and semi-arid regions as a nutrition health crop, which has garnered considerable research attention. We evaluated the effects of replacing chemical nitrogen fertilizers with organic fertilizers on two primary plant accessions of foxtail millet (Dungu and Jinfen no. 2). Nitrogen in a standard fertilizer was replaced with organic fertilizer at application levels of 0, 25, 50, 75, and 100%, with effects on crop yield, quality (appearance, taste, and nutritional value), and soil microbiome, assessed using field cultivation experiments. Our results indicate that partial replacement of conventional fertilizers with organic fertilizers improved both yield and quality. Specifically, the 75% replacement significantly improved the appearance (yellow pigment content and grain diameter) and taste (amylose content and soluble sugar content) of foxtail millet, while the 50% replacement significantly improved the taste (gel consistency) and nutritional qualities (crude protein content and seven amino acids’ content). The 50% replacement of organic fertilizer regulated amino acid content more significantly than starch content. Increased ratios of organic fertilizer significantly reduced the soil pH by 0.03–0.36 and increased the relative abundance of Chloroflexi as well as that of Basidiomycota and Cercozoa in the soil microbiome. Our findings provide a solid theoretical foundation for subsequent studies on fertilizer use for foxtail millet and contribute to developing functional nutritional foods in the foxtail millet industry. Full article

Recycling waste, such as rice straw and water treatment residuals, is important to reduce harmful effects on the environment and to improve canola yield and soil quality in degraded soils. Nanotechnology for the production of nanomaterials from biochar and water treatment residues will be a future revolution for improving soil quality and increasing canola yield in degraded soil. Therefore, this study aims to identify the properties of some recycled nanomaterials, such as nanobiochar (nB) and nanowater treatment residue (nWTR), and their effect on the biological activity and productivity of canola in degraded soils. The results showed that the nWTR and nB contain many functional groups and minerals, and they also have high negative zeta potential. The addition of the studied soil amendments significantly improved microbial biomass carbon (MBC) and biological activity, which played a major role in increasing canola yield. The highest dehydrogenase (DHA) and catalase (CLA) activity was found in nWTR-treated soil at 50 mg kg⁻¹, with increases of 32.8% and 566.7% compared to the control, respectively. The addition of nB greatly improved the growth of canola plants in the soil. This was evident from the increase in the weight of seeds, the weight of 1000 grains, the number of pods per plant, and the highest increase was for nB added at the rate of 250 mg per kg⁻¹ soil. The addition of 50 mg kg⁻¹ of nWTR gave the best results in seed yield by 150.64% compared to the control. These results indicate that recycled nWTR and nB are some of the best waste recycling treatments, in addition to good soil health, in increasing soil biology and canola yield in degraded soils. In the future, research on recycled nanomaterials should examine the residual effect they have on yield, soil quality, and soil fauna in the long term. Full article

Excessive application of nitrogen (N) fertilizer will cause many adverse consequences in paddy fields, especially for the reduction in N use efficiency. Biochar can be used to replace part of N fertilizer for rice production. A field experiment of 2-year/four-season was conducted to investigate the effects of N fertilizer reduction combined with rice straw biochar application on rice yield, soil fertility, and N use efficiency. The experiment contained six treatments: No N application (CK), customary N application (N100), 20% N reduction (N80), 20% N reduction + biochar (N80+BC), 40% N reduction (N60), and 40% N reduction + biochar (N60+BC). Compared with N100, N reduction alone had no significant impact on the number of tillers and aboveground biomass of rice, exceptfor N60 which slightly reduced grain yield, while biochar incorporation tended to obtain higher tillers, aboveground biomass, and grain yield of rice compared with N reduction alone. The average contribution of biochar to grain yield on the basis of N80 and N60 were 5.8% and 7.7%, respectively. Notably, biochar incorporation further improved the agronomic N efficiency (54.5–309.4% over N100) and apparent N recovery (25.7–150.5% over N100) on the basis of N reduction. Furthermore, biochar application could not only maintain N nutrition level of rice, but also improve soil fertility mainly by increasing soil pH and organic matter. Therefore, integrated application of mineral N fertilizer and biochar is a feasible nutrient management measure to increase rice yield and soil fertility, and improve N use efficiency in paddy ecosystem. Full article

A 2020–2021 study was performed on five-year-old guava trees to examine the influence of the foliar application of three amino acids, glycine, arginine, and glutamic acid, at a concentration of 500 or 1000 ppm. Additionally, two combinations of the three mentioned amino acids were also applied: 500 glycine + 500 arginine + 500 glutamic acid (combination 1) and 1000 glycine + 1000 arginine + 1000 glutamic acid (combination 2), and compared with a control (untreated trees). The results indicated that the application of the three amino acids, solely or in combination, was effective at increasing the shoot length, shoot diameter, and leaf chlorophyll. Additionally, the applied treatments also improved markedly the fruit set percentage, fruit yield, fruit firmness, fruit content of total soluble solids (TSS %), vitamin C (VC), and total sugars as well as the leaf mineral content (nitrogen, potassium, and phosphorus) compared with untreated trees in 2020 and 2021. Moreover, the results indicated that the combinations were more effective than individual applications and that glycine had a greater influence than arginine or glutamic acid, particularly when it was applied at 1000 ppm. Full article

Winegrape cultivation has become increasingly common throughout northwest China over the past 20 years, and such viticulture can profoundly impact the properties of the utilized soil and the associated soil microbial communities. To explore these effects in the present study, samples of soil were collected from control desert soil and from vineyards planted in different years: Cabernet Sauvignon (CS, 2014), Merlot (M, 2012), and Italian Riesling (IR, 2008). The properties of this soil and the microbial communities therein were assessed through a series of physicochemical, enzymatic, and high-throughput sequencing analyses. Compared to the control soil, respective 1033.06 U/g, 398.28 U/g, and 240.56 U/g increases in alkaline phosphatase activity levels were observed in the CS, M, and IR soil samples. Stable soil bacterial richness was observed in the control, CS, and M samples, but decreased in the 11-years old IR soil, whereas no noticeable changes in soil fungi were observed across these samples. The network analyses highlighted correlations among soil microbes, and soil organic carbon and microbial biomass carbon were found to strongly influence variability in these soil microbial communities. Overall, these findings thus provide strong evidence that the prolonged monoculture of winegrapes can contribute to the deterioration of soil quality. Full article

The effect of beneficial soil fungi, bacteria and mineral fertilizers containing nitrogen, phosphorus and potassium on the level and species composition of weed infestation, uptake of macronutrients by weeds and the nutritional status of ‘Sampion’ apple trees with nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) was assessed in three-year studies. In the field experiment, the effect of thirteen treatments was investigated, where fungal or bacterial inocula and mineral fertilizers at a standard dose and a dose reduced by 40% were applied individually or together. The fungal inoculum contained two species: Aspergillus niger and Purpureocillium lilacinum. The bacterial consortium consisted of three Bacillus strains: Bacillus sp., Bacillus amyloliquefaciens and Paenibacillus polymyxa. The weight of weeds and the uptake of macronutrients by weeds in the apple orchard increased significantly more after the application of mineral fertilization than after the application of beneficial organisms. The increased uptake of macronutrients by weeds did not significantly change the mineral nutritional status of apple trees expressed as the content of N, P, K Mg and Ca in apple leaves. After the use of NPK mineral fertilization, also with the addition of beneficial organisms, the uptake of N by both weeds and apple trees increased. P and K were more efficiently absorbed by weeds and they achieved greater benefits from fertilization with these two macroelements than trees. Full article

Farmers are increasing the use of fertilizers in chestnut, the only cash crop produced in the mountainous areas of northeastern Portugal. This calls for more studies to guide them towards a more ecological intensification. The effects of three controlled-release fertilizers, two that release nutrients over three months (BoskGrow 20:05:20_3m, Exactyon 18:05:13_3m) and one over six months (Exactyon 18:05:12_6m), and an organic amendment authorized for organic farming (Humix 12:03:05) were compared with an untreated control during a three-year field trial (2019–2021). BoskGrow 20:05:20_3m, Exactyon 18:05:13_3m and Humix 12:03:05 gave significantly higher nut yields (90.6 to 97.0 kg tree⁻¹, average 2019 + 2021) than Exactyon 18:05:12_6m (66.3 kg tree⁻¹) and the control (69.5 kg tree⁻¹). Leaf concentrations of nitrogen and potassium tended to be higher in the BoskGrow 20:05:20_3m and Exactyon 18:05:13_3m treatments, and they were stated as the most important causes in the establishment of the two productive groups. Humix 12:03:05, although less concentrated in nutrients, led to a chestnut yield at the level of the most productive treatments, possibly due to the multiple positive effects of organic matter on soil and plants. Under the conditions of this experiment, where rainfall is low in the summer, fertilizers whose nutrient release takes a long time, such as Exactyon 18:05:12_6m, seem not to be a good fertilization option due to reduced nutrient uptake and increased levels of soil inorganic nitrogen at the end of the growing season. Humix 12:03:05 emerged as a possible solution for organic producers. Full article

In low-input farming systems, where plant nutrition strongly depends on either organic matter inputs or nitrogen fixation by legumes, it is crucial to understand the effects of different crop residue management strategies on microbially mediated processes that influence nutrient dynamics. To evaluate different straw management options, we conducted a pot experiment with the following treatments: (1) control with no straw added (CON), (2) applying straw to the soil surface (SRF), simulating no-till, and (3) straw incorporating straw to the top 10 cm (INC), simulating minimum tillage. Another factor was slurry fertilization (with 3.2 t d.m. ha⁻¹ or without). Throughout the experiment, CO₂ efflux (µmol/m²/s) was measured regularly over a period of four months. Soil sampling was performed to monitor the abundance of the total bacterial, crenarchaeal and fungal communities, as well as nitrogen cycle microbial guilds and the dynamics of labile N and C fractions in the soils at different depths. Among straw treatments, significantly higher soil respiration was observed in INC and SRF compared to CON. Slurry fertilization increased soil respiration in all straw treatments. In the top 10 cm soil layer, the fungal abundance increased in INC compared to SRF and CON, whereas bacteria and crenarchaea did not respond. This effect was even more pronounced with slurry addition. The slurry also stimulated the abundance of certain N-cycle guilds, with the greatest increase in bacterial amoA-bearing nitrifiers and nirS, nosZI and nozII-bearing denitrifiers, particularly in the uppermost 0–1 cm soil layer. Straw treatment effects on N-cycle microbial guilds were less pronounced, while the coupled effect of straw incorporation and slurry was beneficial mostly for nosZ, again mainly in the top 1 cm soil layer. Compared to straw management, slurry fertilization had more potent effects on the abundance and performance of the investigated microbial communities. Full article

Muscadine (Vitis rotundifolia) is a grape species that is native to the Southeastern US, where several cultivars are grown commercially for processing or direct consumption. Phenology based tissue analysis to determine the nutritional status of a vine is a critical tool for growers to understand fertilizer demands in a vineyard. For European-style wine grapes, tissue sampling for nutrient content is well researched. However, current tissue sampling recommendations for muscadines are solely based on anecdotal knowledge. It is currently unknown if the type of tissue collected has an impact on variability and content of nutrients. Questions also remain as to whether or not seasonal vine phenology impacts tissue nutrient content. Without this knowledge it is difficult for a muscadine grower to make informed decisions on the nutritional status of a muscadine vine. Therefore, we investigated the impact of the phenological vine stage (bloom, fruit set, véraison) on nutrient content in two different tissue types (mature leaf vs. petiole), sampled at two different positions on a muscadine vine (opposite of cluster vs. shoot). The study was conducted over two growing seasons (2019 and 2020) in a commercial mature muscadine vineyard (‘Carlos’). Our results show that over both study years, the highest variability in nutrient content was found during bloom (May–June), while nutrient variability was lower during fruit-set and veraison. We also found fully mature leaf samples showed a lower variability in nutrient tissue content. Based on our results, sampling fully mature leafs from shoots remains the best practice. However, our results also indicate that tissue sampling later in the season might be a better practice, compared to the current practice of taking samples during June. Full article

Sewage sludge ash (SSA) as a secondary phosphorus (P) source may help to conserve global rock phosphate deposits if used in the base fertilization of soilless growing media. Plant availability of SSA-P was studied in a pot experiment with marigolds in a peat-based growing medium of contrasting pH (4.5, 6.0). Six SSAs were included in the study and compared to water-soluble monocalcium phosphate (MCP) and rock phosphate (RockP). In addition to the efficacy of SSA-P, calcium chloride + diethylenetriaminepentaacetate (CAT) and calcium-acetate-lactate (CAL), as commonly used extractants in Germany to analyze plant-available P in growing media, were tested in terms of their ability to predict plant P uptake. No SSA reached the relative P use efficiency (rPUE) observed for MCP. However, at a growing medium pH of 4.5, the average rPUE for SSA was 70% of the MCP rPUE. Compared to RockP, at a growing medium pH of 6.0, SSAs resulted in an rPUE of nearly the same low level. In contrast, at pH 4.5, the rPUE from SSAs was mostly lower than that from RockP, and there were differences in rPUE among SSA origins. Therefore, in addition to a variation in particle size distribution, there might be differences in the P-bearing phase. Sewage sludge ashes represent a promising substitute for primary P sources only in crops requiring a low pH in the growing medium. The extractants CAT and CAL, on their own or in combination, did not reflect plant P uptake from SSA. To improve the prediction of plant-available SSA-P, solvent modifications or additional extractants might be promising and should be subjected to further research. Full article

Phosphorus (P) is a major nutrient for plant growth and animal health, and its availability in soil is influenced by agronomic management and soil properties. This study examined the distribution of labile and non-labile soil P fractions in grassland and the properties that influence their distribution in temperate grasslands. Eleven fractions were identified as, labile (H₂O.P and NaHCO₃.P), moderately labile (NaOH.P) and plant non-available (NaOH.P, HCl.P and residual P). The residual P, moderately labile organic (NaOH.Po) and inorganic (NaOH.Pi) fractions comprised 38%, 24% and 15% of the total P (TP), respectively. The residual and organic (Po) fractions were associated with extractable Fe, and the NaOH.Pi fraction was associated with extractable Al. Agronomic reagents (Morgan’s and Mehlich3) targeted specific fractions based on their affinity for different soil elements. Morgan’s P was associated with extractable and residual Ca and in high Ca soils, and overestimated plant-available P by extracting non-labile Ca.P forms (HCl.P). The Mehlich3 P test was associated with NaOH.Pi fraction and showed a preference for Al.P oxides. This study indicates that Mehlich3 reagent, which provides a wider suite of elements such as P, Ca, Al and Fe, will suit as a better indicator for soil P dynamics and improved P advice to farmers. The inclusion of additional soil chemico-physical characteristics would improve agronomic soil testing, benefitting farmers’ advice. Full article

Due to long-term excessive fertilization, the fruit quality of the Guanxi pomelo (Citrus grandis) has been declining. The classification of fruit quality and its relationship with nutrients in soils and trees were studied to declaim the characteristics of nutrients in Guanxi pomelo orchards, ultimately guiding the fertilization for high-quality fruit production. By cluster analysis, 281 samples were grouped into four clusters. High-quality fruit (HF) showed a gourd shape with moderate weight size, high sweetness, edible rate (ER) up to 73%, and vitamin C content over 40 mg/100 g. Compared to sub-quality fruit (SF), common fruit (CF), and inferior fruit (IF), the content of magnesium (Mg) in the leaves of HF was 11.76, 11.76, and 18.75% higher, while the content of iron (Fe) was 6.45, 5.76 and 10.97% higher, respectively. Meanwhile, the contents of Zinc (Zn, 8.51, 6.44, and 11.22% higher than SF, CF, and IF, respectively) and Boron (B, 13.47, 13.83, and 25.40% higher than SF, CF, and IF, respectively) were also found to increase. However, the contents of Mn (35.34, 27.51, and 25.53% higher) and Cu (31.90, 31.99, and 5.64% higher) in IF were significantly higher than in HF, SF, and CF. Acid soils (4.24–4.40) with low OM content (23.00–26.71 g kg⁻¹) led to an imbalance uptake of nutrients of citrus, ultimately resulting in poor quality. These results indicated that farmers should reduce the application of nitrogen (N), phosphorus (P), and K fertilizer and pesticides and increase micronutrient and organic fertilizer, which provides a theoretical basis for scientific fertilization to improve the fruit quality of Guanxi pomelo (Citrus grandis) of Pinghe County. Full article

The aim of the study was to evaluate the effect of various fertilization treatments, including nitrogen, potassium and phosphorus fertilization, in long-term experiments for selected UAV (unmanned aerial vehicle)-derived spectral vegetation indices (NDVI—Normalized Difference Vegetation Index, NDRE—Normalized Difference Red Edge Index, VARI—Visible Atmospherically Resistant Index, TGI—Triangular Greenness Index, SIPI2—Structure Insensitive Pigment Index 2, LCI—Leaf Chlorophyll Index, BNDVI—Blue Normalized Difference Vegetation Index, GNDVI—Green Normalized Difference Vegetation Index, MCARI—Modified Chlorophyll Absorption in Reflective Index) based on multispectral (bands in the range of visible light and near infra-red) images of winter rye. The strongest effect on the studied vegetation indices was nitrogen fertilization, which discriminated values of most of the vegetation indices. The effect of phosphorus and potassium fertilization on the studied vegetation indices was much weaker. The treatments with nitrogen fertilization had significantly higher values of most vegetation indices in comparison to treatments without nitrogen. This was confirmed by principal component analysis (PCA), in which treatments without nitrogen fertilization were very different in comparison to all other treatments where nitrogen fertilization was applied. The effect of phosphorus and potassium fertilization on most of vegetation indices was relatively weak and not significant in most experiments. Only for rye cultivated in monoculture was the effect of phosphorus fertilization significant for most of vegetation indices in early growth stages. In later growth stages (heading and flowering) the effect of phosphorus fertilization was significant in rye monoculture for the SIPI2 vegetation index. Mean SIPI2 was higher for the fertilization treatment CaNPK in comparison to CaKN (without P fertilization). The effect of potassium fertilization on the studied vegetation indices was very weak, and in most cases not significant. The effect of nitrogen fertilization on vegetation indices was much stronger than effect of both potassium and phosphorus fertilization. Full article

A vegetable’s high antinutrients, nitrate (NO₃⁻) and oxalate, could be remediated by neem seed extract. The combined use of neem seed extract with mineral fertilizer and cricket frass was conducted to evaluate their effects on amaranth’s tissue NO₃⁻ and oxalic acid contents by inhibiting nitrification. The effects of five soil amendments were investigated: unamended, mineral fertilizer, and three rates of cricket frass (3.125 Mg ha⁻¹, 6.25 Mg ha⁻¹, and 12.5 Mg ha⁻¹), combined with two rates of neem seed extract: without (−Nm) and with (+Nm) extract. Only the neem extract applied to soils receiving mineral fertilizers decreased soil tissue NO₃⁻−N contents (0.82 g kg⁻¹ for −Nm vs. 0.62 g kg⁻¹ for +Nm). The oxalic acid content of amaranth decreased with mineral fertilizer (0.60 and 0.46 g kg⁻¹ for −Nm and +Nm, respectively), yet increased with the higher rates of cricket frass (1.42–1.52 g kg⁻¹ for −Nm, and 1.23–1.51 g kg⁻¹ for +Nm) compared to the unamended soil (1.05 and 1.00 g kg⁻¹ for −Nm and +Nm). Cations, including K, Ca, Mg, and Na derived from cricket frass, may enhance biosynthesis and the accumulation of oxalic acid. The neem seed extract decreased the tissue’s oxalic contents regardless of soil amendments. Full article

Long growing seasons, relatively shallow root system, coarse textured soils, and variability of the subtropical environmental conditions of the southeastern U.S. create challenges for nitrogen (N) fertilizer management of short-day onions. The objectives of this study were: (i) to evaluate the impact of fertilizer N rates on the yield and bulb quality of three short-day onion cultivars grown under the subtropical conditions of the southeastern U.S., and (ii) to assess the impact of fertilizer N rate for short-day onions on consumers’ preference. Field experiments were conducted in 2019 and 2020 at the Vidalia Onion and Vegetable Research Center at the University of Georgia located in Lyons, GA, in which a two factorial experimental design of five fertilizer N rates (84, 101, 117, 134, and 151 kg of N ha⁻¹) and three short-day onion cultivars (Sweet Agent, Vidora, and Quick Start) was evaluated in a randomized complete block design. During both growing seasons, rainfall events directly impacted soil mineral N content. While soil mineral N availability increased with fertilizer N application, there was no significant difference among fertilizer N rate treatments due to rainfall distribution in both years studied, except at bulb initiation when the application of 117 kg of N ha⁻¹ sustained soil mineral N availability that maximized with the application of 128 kg of N ha⁻¹. Onion total yield averaged 37,365 kg ha⁻¹ in 2019 and 34,699 kg ha⁻¹ in 2020. In general, colossal, jumbo, and medium-sized onions represented 7%, 76%, and 17% of total yield, respectively. Jumbo-sized onions are of most interest to growers due to their high value, and the yield of jumbo-sized onions was maximized with 158 kg of N ha⁻¹ in 2019 and with 138 kg of N ha⁻¹ in 2020. Bulb bacterial rots were not impacted by fertilizer N rate treatments. Contrarily, bulb gallic acid (GAE) linearly increased and pyruvic acid quadratically increased with the application of fertilizer N rate. Ultimately, a taste panel indicated that sensory characteristics were also not affected by different rates. Overall, a fertilizer N rate application of 117 to 134 kg of N ha⁻¹ could sustain soil mineral N availability without impacting yield; however, an investigation on the timing of application should be conducted to determine a fertilizer N strategy that will promote optimum yield, bulb quality, flavor, and consumer acceptability. Full article

Cover crops can determine positive benefits on soil fertility and rice productivity, although scant attention has been devoted to evaluating the effects of hairy vetch (Vicia villosa Roth) and the incorporation of rice straw with different N fertilization levels on soil N and P availability and crop yields in temperate cropping systems characterized by poorly developed soils. In this study, the effects of cover crops grown before rice in a temperate mono-cropping system (NW Italy) on: (i) crop yields and yield components; (ii) apparent N fertilizer recovery and optimal level of N fertilization with hairy vetch; and (iii) temporal variation of soil available N and P forms during the hairy vetch growth and rice cropping season, have been investigated. The cultivation and incorporation of hairy vetch in the rice cropping system increased grain productivity by 12%, while reducing N mineral fertilization requirements by 33%. Combined with the incorporation of crop residues, hairy vetch provided a N and P input of 178 and 18 kg ha⁻¹, respectively, representing a readily available source for plant uptake over the whole rice cropping season, particularly under anaerobic conditions. This results in a better temporal synchronization of soil N and P availability with crop nutrient demand, leading to a better rice grain productivity and quality performance. Full article

Glomalin-related soil protein (GRSP), soil nutrients, and soil enzyme activities are closely related to soil fertility and land productivity, which play an important role in indicating soil quality. Little is known about the spatial variation in GRSP and its relationship with edaphic factors. Here, the spatial distribution of GRSP, soil chemical properties, and the soil enzyme activities of 0–20 cm depth farmland soil in the black soil region of northeast China were investigated, and the relationships among edaphic factors were analyzed collected from 41 sampling sites. The results indicate that GRSP, soil organic matter, total nitrogen, and acid phosphatase activities showed significant patterns of spatial variation, generally decreasing from north to south along a latitudinal gradient. Principal component analysis revealed that total GRSP (by 80.19%) and soil organic matter content (by 80.15%) were the greatest contributing factors accounting for the variations. Edaphic factors such as soil organic matter, total nitrogen, total phosphorus, and acid phosphatase were significantly positively correlated with GRSP, while urease was negatively correlated with GRSP. Mantel tests also showed that soil organic matter, total nitrogen, urease, and acid phosphatase were positively correlated with GRSP. The results reflect the soil fertility characteristics of the black soil region of northeast China and reveal the relationship among edaphic factors. These findings could be used to inform agricultural production and provide new insight into the role of GRSP in soil quality. Full article

The application of enzymatic kinetics theory on the nutrition of horticultural species is scarce. I_max and K_m describe the kinetics of nutrient absorption by the plant. I_max and K_m are necessary to predict phosphorus (P) uptake from soil using mathematical models, and their estimation gives information about the efficient use of P in plants. I_max and K_m for habanero pepper (Capsicum chinense Jacq. cv. Mayapán) were determined using the modified exhaustion method. Depletion of P by the roots was obtained with 0.01, 0.125, 0.25, 0.50, and 1.00 mM P L⁻¹. P-depletion data over time were fitted to an exponential-regression model to obtain the initial P-uptake rates by the roots. Initial P-uptake rates were significantly different (p < 0.001) depending on the levels of P in the solution. I_max and K_m were predicted by iteratively fitting the initial P-absorption rates in terms of the concentration of P to the Michaelis–Menten model. The average I_max was 3.49 × 10⁻⁷ mM cm² s⁻¹ and K_m was 2.59 × 10⁻² mM P L⁻¹. These results show that the habanero pepper root can uptake 1.08 × 10⁻⁵ mg P L⁻¹ per cm² in the soil solution per second and P transporters are saturated with 2.59 × 10⁻² mM P L⁻¹. Full article

Long-term rotary tillage leads to thinning of the soil layer and low nitrogen use efficiency of crops, resulting in a decrease in crop yield and quality. Therefore, a new alternative method to improve nitrogen use efficiency of crops needs to be found urgently. Here, we analyzed the effects of a new smash ridge tillage method combined with reduced nitrogen application on tobacco growth and development, and nitrogen use efficiency and its economic benefits. The results showed that, compared with conventional tillage and nitrogen application of 180 kg N ha⁻¹, smash ridge tillage and a 30% reduction in nitrogen rate resulted in greater root length density, more primary lateral roots and greater rooting depth in the subsoil. It is also beneficial to maintain a high level of biomass and nitrogen accumulation in the later growth period, increasing the output value of tobacco by CNY 1588.35 ha⁻¹ and reducing the cost by CNY 974.1 ha⁻¹ on average in two years. In conclusion, our study highlights the economic benefits of smash ridge tillage and nitrogen reduction for tobacco growth and development, and considers them an effective method for improving agricultural productivity and nitrogen use efficiency. Full article

Fish drainage water is a non-conventional water resource that can be exploited for irrigation due to its constituents of beneficial nutrients, signifying it as environment-friendly bio-fertilizers. Limited water resources, the elevated cost of mineral fertilizers hazards as well as attaining healthy food are of paramount significance in the agriculture sector in Egypt. The utilization of bio-fertilizers is an avenue to fulfil agricultural sustainability, production of clean crops and preservation of the soil from the accumulation of heavy metals and chemicals. Hence, this study aims to find non-conventional alternative water resources to be used for irrigation of pomegranate fruit yield. Two resources of water were utilized, and three types of bio-fertilizers were applied. Results showed that, fish drainage water increased the total yield (kg/fed) by 25.2% as compared to freshwater. Chicken manure increased the total yield (kg/fed) by 22.37 and 11.89% in comparison with cattle and compost organic fertilizer under fish drainage water, respectively. The use of chicken manure yielded the highest net return (2420.79US $/fed), while compost and cattle dung were found to be (2123.52US $/fed) and (1721.66US $/fed), respectively, under using fish drainage water. The study showed that the use of fish drainage water as an organic resource would be an alternative to commercial fertilizers, which could reduce the total cost and thus increase the net profit and yield. Less dependency of commercial fertilizer would have an impact on reducing the emissions of CO₂ mitigating global warming. Full article

Application of the organic fertilizers can improve soil properties and agricultural product quality, while the in-depth effect of organic fertilizer needs further exploration. In this study, the apple fruit (Malus pumila Mill.) quality, soil physicochemical characteristics, and microbial community under different fertilizers including control without fertilizer (CK), composted manure (CM), biogas slurry (BS), and chemical fertilizer (CF) were systematically investigated, and each treatment was repeated three times in completely random block plots with equal NPK content of fertilizer applied in each treatment. The CM treated apple fruit were observed with the best vertical diameter (78.72 ± 4.32 mm), transverse diameter (87.51 ± 1.3 mm), and color index (L* = 55.48 ± 5.48, b* = 18.96 ± 1.86). Meanwhile, the CM and BS treated apple fruit had higher flesh firmness than that of CK and CF treatment, implying that the organic fertilization can improve the storability and crispy taste apple fruit. Furthermore, the total sugars, essential amino acid, crude protein, total acids, and soluble solid contents of apple fruit were also significantly improved by using CM and BS fertilizer due to the resulting higher N, P, and organics content in soil. The application of organic fertilizer also dramatically enhanced the bacterial and fungi diversity, which may contribute to better soil respiration. The results obtained in this study reveals the insight effect of organic fertilizer on improvement of fruit quality and soil health and can supply technical assistance to organic cultivation of apple. Full article

Drought stress and phosphorus (P) deficit decrease soybean P and nitrogen (N) accumulation, which limits soybean productivity. Therefore, soybean traits related to N and P uptake and/or their efficient utilization are important for soybean adaptation to P- and water-deficit conditions. We hypothesize that increasing soybean nodulation to enhance N and P uptake, and/or improving N and P use efficiency (PUE and NUE) are important for the adaptation of soybean to drought and low P conditions. To test this hypothesis, we selected four genotypes with different nodule dry weight (DW) and yield performance for a pot experiment under two water treatments [well-watered (WW) and cycle water stress (WS)] and three P levels [0 (P0, low), 60 (P60, mid), and 120 (P120, high) mg P kg⁻¹ dry soil on top 40 cm]. Our study showed that P deficit and water stress significantly decreased soybean P and N accumulation, which limited seed yield under both WS and WW conditions. P addition increased soybean nodule dry weight (DW), thus increasing N and P uptake. Increasing nodule DW required high water use, and while there was no relationship found between nodule DW and yield under WS, a positive relationship under WW was shown. Partitioning more dry matter to seed could improve NUE and PUE. P addition did not change soybean NUE, which is important to yield determination under WS and P0 but has no effect on yield under WW. We conclude that increasing nodule formation improved soybean N and P uptake, which diminished the yield loss under WS and improved yield performance under WW. While high NUE reflects efficient utilization of N, which can improve yield under drought stress and low P availability, and does not impair the yield under WW. We propose that NUE and nodules are important traits for breeders to improve the tolerance to water- and P-deficit conditions. Full article

Agroforestry not only takes into account the use of land for forestry and agriculture but can also improve the efficacy of utilized above- and belowground resources, which have always garnered widespread attention. The objective of this study is to evaluate the quality of pecan orchard soil following the implementation of agroforestry. Consequently, 15 indices were selected for a principal component analysis (PCA), which was then combined with the norm value of each index and the correlation coefficients between indices to establish a minimum data set (MDS). A comprehensive index model was used to calculate the soil quality index (SQI) of the total data set (TDS) and MDS (SQI-TDS and SQI-MDS, respectively), and a linear regression of the two was performed. The results revealed that the MDS indices for the evaluation of soil fertility included the pH, electrical conductivity value (EC), bulk density (BD), available potassium (AK), total nitrogen (TN), magnesium (Mg), and the index screening and filtering rates attained 60%. The Soil Quality Index (SQI-MDS) of the four planting patterns, sorted from largest to smallest, were: PPS (0.573) > PPH (0.519) > PPL (0.355) > CK (0.315). BD and AK were the main factors that affected the quality of hickory orchard soils. The agroforestry composite system improved the availability of nutrients and soil quality. Thus, the promotion of understory intercropping and appropriate increases in potassium fertilizers for plantations are recommended. Full article

The need for effective nutrient management is crucial for optimizing wheat production and increasing the plant’s ability to tolerate different environmental stresses. In this study, we assessed the influence of new-generation PGRs and foliar topdressing nitrogen fertilizer and their interactive effects on wheat yield and quality parameters of grain and flour. A three-year field experiment was conducted on the dark chestnut soil of the Rostov region. We estimated the effect of foliar topdressing liquid nitrogen fertilizer on consumption rates of N32 (N32), N64 (N32 + N32), and N96 (N32 + N32 + N32), as well as new-generation plant growth regulators (PGRs), namely, Zirkon, Silk, and Albit, on the productivity and grain quality of winter wheat Tarasovskaya 70. The results of the experiments indicate that the highest average grain yield over three years was 5.34 t/ha⁻¹ with the application of N96 (N32 + N32 + N32) and Albit PGR. In 2020, due to favorable weather conditions, the greatest grain yield was attained at 6.27 t/ha⁻¹ for N96 (N32 + N32 + N32) and Albit PGR. The highest grain quality with the greatest gluten content >28% was obtained when N96 (N32 + N32 + N32) and PGRs were applied. According to the results, using N96 (N32 + N32 + N32) and PGRs made it possible to obtain “valuable” grain in terms of quality, which is suitable for the production of premium flour. The beneficial interactive effects of N application rates and PGRs on winter wheat yield and quality parameters are worthy of further investigation. Full article

To trace the phosphorus (P) and potassium (K) content in flooded rice (Oryza sativa L), 14 rice cultivars commonly grown in the Southern United States were evaluated for their P and K concentration in tissue and grain. Field experiments were conducted at two locations in Everglades Agriculture Area (EAA), where flooded rice was cultivated on organic Histosols. Soil pH and Mehlich-3 phosphorus (M3P) were significantly different between locations. At Site I, soil pH, M3P, and Mehlich-3 potassium (M3K) varied in the range of 6.8–7.1, 21.4–36.4 mg kg⁻¹, and 53.9–151.0 mg kg⁻¹, respectively. At Site II, soil pH, M3P and M3K varied in the range of 6.9–7.3, 11.2–20.5 mg kg⁻¹, and 64.8–104.1 mg kg⁻¹, respectively. Stem potassium was the only measured parameter that was significantly different among rice cultivars at both sites. At Site I and Site II, stem K ranged from 14.2–26.6 mg kg⁻¹ and 10.4–19.4 mg kg⁻¹, respectively. No significant difference in yield among cultivars was observed at Site I, whereas Site II had a significant difference in yield among cultivars. At Site I and Site II, yields ranged from 3745–7587 kg ha⁻¹ and 2627–6406 kg ha⁻¹, respectively. None of the cultivars ranked consistently in the same top and bottom position for each measured parameter. Total phosphorus (TP) concentration was highest in grain, whereas total potassium (TK) concentration was highest in the stem. Results suggest incorporation of rice stem into the soil could potentially add fertilizer back to the soil which helps in fertility management. Full article

Under the economic pressure from the increase of fertilizers’ prices due to the recent energy crisis, more efforts are needed to search for alternative and cheaper sources of nutrients for crops. The purpose of our study was to compare the effects of manure and inorganic amendments’ application to those derived from the application of a controlled-release fertilizer (CRF) on the growth, nutrition, physiology and fruit quality of pepper plants. For that reason, zeolite (ZEO) and vermiculite (VER) were applied either independently, or in combination between them, or with manure (MAN), in a pot experiment. Insignificant differences for plant growth among the treatments were recorded, while higher foliar N, Mg and Mn concentrations were determined in CRF. In contrast, a significantly higher K uptake was recorded in the ZEO and VER + ZEO treatments; the highest leaf P levels (0.47 and 0.44% D.W.) were recorded in the MAN + VER and ZEO treatments, respectively. The optimum photosynthetic II (PSII) performance was observed in the VER and in the MAN + ZEO (based on the performance index—PI) treatments. The highest stomata opening was found in the CRF treatment, while the photosynthetic rate of pepper plants showed its maximum values both in the CRF and VER treatments. Finally, fruit quality (as indicated by total soluble solids, total phenols and antioxidant activity—FRAP) was significantly influenced by treatment. In conclusion, significant differences in the growth, nutrition and physiological performance of pepper plants between soil amendments’ application (inorganic, such as zeolite and vermiculite, and organic, such as manures) and CRF application were recorded; thus, these amendments should be more thoroughly studied in future projects to investigate if they could partially decrease high inorganic fertilization rates in Capsicum annuum L. Full article

In a wheat/maize rotation system, nitrogen (N) accounts for a large proportion of basal fertilizer, but soil N loss and the resulting environmental risk simultaneously exist worldwide. This study applied different urease/nitrification inhibitors together with basal fertilizers and investigated their effects on soil N level and grain yield. Six N stabilizing combinations consisted of two urease inhibitors (HQ and NBPT) and three nitrification inhibitors (DCD, DMPP, and Nitrapyrin). The treatments supplied with urease/nitrification inhibitors reduced, to some degree, the conversion rate of ${\mathsf{N}\mathsf{H}}_4^{+}$ into ${\mathsf{N}\mathsf{O}}_3^{-}$, and kept ${\mathsf{N}\mathsf{H}}_4^{+}$ content higher in surface soils for a longer time. Compared to CK, A1 treatment supplied with 1.5% HQ + 4% DCD well-maintained the levels of soil alkali-hydrolyzable N and ${\mathsf{N}\mathsf{H}}_4^{+}$. For example, alkali-hydrolyzable N and ${\mathsf{N}\mathsf{H}}_4^{+}$ contents at 0–20 cm soil layer under A1 were increased by 8.59–41.6% and 8.15–14.5% more than CK, respectively. Based on the entire growth period of wheat and maize rotation, urease/nitrification inhibitors improved soil available N in surface soils but did not prevent ${\mathsf{N}\mathsf{H}}_4^{+}$ and ${\mathsf{N}\mathsf{O}}_3^{-}$ leaching, especially in the intensive rainfall season. The combinations of HQ and DCD or Nitrapyrin significantly enhanced crop yield. Specifically, crop yields under A1 and A3 (1.5% HQ + 0.25% Nitrapyrin) were 16.3% and 14.3% higher than CK, respectively. The N stabilizing combinations also promoted N intake and transport at every growth stage. The maximum N accumulation was increased by 27% under A1, when compared to CK. The treatments supplied with urease/nitrification inhibitors also achieved higher apparent N recovery efficiency, N agronomic efficiency, and N partial factor productivity. Consequently, the combinations of urease/nitrification inhibitors could improve N availability at 0–40 cm soil layer, which in turn improved N use efficiency of wheat and maize. The results suggested that the two urease/nitrification inhibitor combinations, 1.5% HQ + 4% DCD (A1) and 1.5% HQ + 0.25% Nitrapyrin (A3), were optimal N stabilizing agents and worthy of further study. Full article

Mulching is regarded as the most important of the three conservation agriculture principles in increasing crop yield in the short term. Thus, the main objective of this study was to investigate the impact of mulch type and mulch application rate on biological nitrogen fixation (BNF), physiological and yield responses of cowpea. A multi-locational (two locations) and multi-seasonal (two seasons) study was carried out under rainfed conditions in the Limpopo Province of South Africa. Three mulch types (Moringa oleifera stems; Moringa oleifera leaves and twigs; and Vachellia karroo leaves and stems) were uniformly spread on the surface at four rates (0, 3, 6, 9 t/ha). The application of mulches, regardless of the rate and type, improved cowpea chlorophyll content and agronomic parameters, such as stem diameter and plant height. Grain yield at Syferkuil responded to the mulching effect in both seasons, while at Ofcolaco, differences were only observed in one of the seasons. Cowpea under control discriminated against ¹⁵N more than under mulched treatments, resulting in more than 70% of the nitrogen being derived from air compared to 50% in mulched plots. This study demonstrated that organic surface mulches improved the physiological responses of cowpea and that organic surface mulches with a lower C:N ratio significantly reduced BNF. Full article

Balangu is a medicinal plant used in the Iranian traditional medicine to treat nervous, hepatic and renal diseases. To determine the effects of Myco-Root biofertilizer and chitosan nanoparticles (Cs-NPs) on the physiological and biochemical properties of balangu (Lallemantia iberica (M.Bieb.) Fisch. & C.A.Mey.) under different irrigation levels, an experiment was laid out as a factorial based on completely randomized design (CRD) with twelve treatments and three replications. The first factor was represented by different irrigation regimes, including no water deficit (90% FC), mild water deficit (60% FC) and severe water deficit (30% FC); the second factor included control (no Myco-Root and Cs-NPs), inoculation with Myco-Root biofertilizer, foliar application of chitosan nanoparticles (Cs-NPs) and co-application of Cs-NPs along with Myco-Root. The results showed that the highest fresh and dry weight, chlorophyll and carotenoid content, chlorophyll index (SPAD) and fluorescence indices were obtained in 90% FC treated with Cs-NPs+ Myco-Root. In addition, the maximum activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POX) was achieved in 60% FC with application of Cs-NPs+ Myco-Root. Moreover, the maximum essential oil content (1.43%) and yield (0.25 g pot⁻¹) were recorded in 60% FC following the application of Cs-NPs+ Myco-Root. Chemical analysis of essential oil showed that germacrene D (31.22–39.77%), (E)-caryophyllene (16.28–19.82%), bicyclogermacrene (7.1–9.22%) and caryophyllene oxide (3.85–6.96%) were the major volatile constituents of balangu. Interestingly, the maximum contents of germacrene D and (E)-caryophyllene were recorded in 60% FC after the application of Cs-NPs+ Myco-Root. Overall, it can be concluded that co-application of Cs-NPs+ Myco-Root could be a sustainable and eco-friendly strategy for improving the essential oil quantity and quality, as well as physiological characteristics, of balangu under water deficit conditions. Full article

Rapid urbanization results in the accumulation of food wastes that can be composted and diverted from landfills. Previous lab incubations demonstrated that food-based composts can increase soil N relative to manure-based composts, but these benefits were not tested within a crop system. We assessed soil fertility and yield of spinach (Spinacia oleracea L.) grown in two different soils in a greenhouse, comparing two food- and two manure-based composts added at the recommended N rate (101 kg N ha⁻¹). We quantified soil N mineralization and resin-extractable phosphorus, spinach biomass (root and shoot), and crop nutrient concentrations and accumulation. Nitrogen mineralization generally peaked four weeks after application, and one food-based compost (but no manure-based composts) increased soil phosphorus at harvest compared to an unamended control. One manure-based compost and one food-based compost produced a higher yield and greater nitrogen, phosphorus, and potassium accumulation than the unamended control, whereas only the food-based compost increased spinach phosphorus and potassium concentrations. There was a positive relationship between yield and compost inputs of potassium and plant-available nitrogen (especially nitrate), suggesting that potassium inputs may also explain differences observed among composts. Our results suggest that food-based compost provides more nutrients than composts made from cow manure fiber. Full article

Background: Knowledge of the responses of soil aggregates to various fertilization practices can contribute to sustainable soil management in urban vegetable agriculture. Aims: The study assessed the soil fertility, dry aggregate stability, and aggregate total carbon (TC) and nitrogen (TN) retention after the reapplication of biochar, and organic/inorganic fertilizers. Methods: Four replicates of ecological sanitation (ECOSAN) manure, NPK fertilizer, corncob biochar (CCB), and CCB, combined with urea and cattle manure (UCF), were established in a randomized complete block design. Results: The application of ECOSAN increased the soil pH and also resulted in significant accumulation of available phosphorus (P), calcium (Ca), and magnesium (Mg). Compared to CCB treatment, UCF + CCB produced significant increases in the TC, TN, P, Ca, and Mg concentrations by 53, 140, 227, 27, and 78%, respectively, and additionally increased the 4.75–2.00 mm large macroaggregates and mean weight diameter. The total carbon increased significantly in microaggregates (>0.25 mm); macroaggregates (4.75–0.25 mm); and in the micro- and macroaggregate fractions of the ECOSAN, CCB, and UCF + CCB treatments, respectively. More so, the TN in micro- and macroaggregates was increased maximally by UCF + CCB and minimally by the CCB treatment. Conclusions: The reapplication of CCB had limited potential for carbon sequestration in soil aggregates, but its combination with UCF better reflects carbon and nitrogen stabilization in micro- and macro- aggregates, with greater potential in large macroaggregates. Full article

Zinc (Zn) biofortification can improve grain yield and nutritional quality in rice, but its effectiveness is subject to agronomic practices and other factors. In a previous study, the application of Zn to soil enhanced grain Zn in lowland rice in well-drained and waterlogged soil, whereas grain Zn in upland rice increased only in well-drained soil. This new study explores the hypothesis that the application of foliar Zn can enhance grain Zn in upland and lowland rice grown under waterlogged and well-drained conditions. Two rice varieties, CNT1 (wetland rice) and KH CMU (upland rice) were grown in containers in waterlogged or well-drained soil with three Zn treatments (no Zn, soil Zn and foliar Zn). For the soil Zn treatment, 50 kg ZnSO₄ ha⁻¹ was applied to the soil before transplanting. For the foliar treatment, 0.5% ZnSO₄ (equivalent to 900 L ha⁻¹) was applied at booting and repeated at flowering and milky growth stages. Grain yield in CNT1 was 15.9% higher in the waterlogged than in the well-drained plants, but the water regime had no effect on grain yield in KH CMU. Grain Zn concentration in CNT1 increased from 19.5% to 32.6% above the no Zn control when plants were applied with soil or foliar Zn. In KH CMU, there was an interaction between the water regime and Zn treatment. Application of foliar Zn increased grain Zn by 44.6% in well-drained and 14.7% in waterlogged soil. The results indicate strong interaction effects between variety, water regime and Zn fertilizer application on Zn biofortification in rice. Thus, the selection of rice varieties and growing conditions should be considered in order for producers to achieve desirable outcomes from high grain Zn concentrations. Full article

Vermicompost (VC) is a nutrient-rich material that is mixed with soil, and it is used in this study. Four different environments were created such as control (Soil:VC:100–0%), mix one (Soil:VC:70–30% w/w), mix two (Soil:VC:50–50% w/w), and mix three (Soil:VC:40:60% w/w), and three well-developed roses (Vinca rosea valiant, Pelargonium peltatum, Pegasus patio) seedlings were transferred to individual pots. Plant growth parameters, i.e., the number of flowers, plant height, stem diameter, chlorophyll reading value, fresh flower weight, and flower dry weight height, were compared with respect to control seedlings. The improvement in the number of flowers, plant height, stem diameter, chlorophyll reading value, fresh flower weight, and flower dry weight height by 264, 71, 58, 255, and 193% for Vinca rosea valiant rosea, 138, 12, 160, 13, 55 and 112% for P. patio rose, and 50, 14, 23, 8, 61, and 41% for P. peltatum, respectively, grown in soil mixed with VC as compared to control. As a result of the research, the optimum growth parameter values and chlorophyll Meter SPAD values were obtained from the mix-three mediums for all three roses species. These results showed that 40% soil and 60% VC application could be proposed as the most effective medium in ornamental plant production. Full article

The Xinjiang cotton-producing region is the main cotton-growing region in China; however, the combination of excessive application but low utilization of fertilizers has restricted its agricultural development. Estimating the balanced nutrient requirements for cotton is essential to increase its yield and nutrient use efficiency. The results from 372 field experiments performed between 1996 and 2019 were used to build a QUEFTS (quantitative evaluation of the fertility of tropical soils) model to investigate relationships between cotton seed yield and nutrient accumulation, with the data from 2017 to 2020 used to validate the model. The results demonstrated that the QUEFTS model predicted a linear relationship between target yield and nutrient uptake until the target yield reached about 60–70% of the potential yield. To produce 1000 kg of seed cotton, 28.3 kg N, 6.1 kg P, and 29.6 kg K were required for cotton, and the corresponding ratio of N, P, and K was 4.64:1:4.85. The corresponding internal efficiencies (IEs) for N, P, and K were 35.4, 163.2, and 33.7 kg/kg, respectively. Field validation indicated that the QUEFTS model could be used to estimate nutrient uptake at a targeted yield and contribute to developing a fertilizer recommendation strategy for Xinjiang cotton production. Full article

Continuous cropping obstacles limit soybean production. Biochar is beneficial for soybean growth, but it is unclear whether biochar performs a sustainable role in continuous cropping. To further explore the effects of biochar on soil properties and soybean growth, a ceramic Wagner pot-simulated field experiment was conducted with biochar at different doses (12, 24, and 48 t·ha⁻¹) over a period of 3 years, no fertilizer, no biochar (CK) and fertilizer (F)treatments were used for comparison. The results showed that biochar significantly reduced soil bulk and improved the rhizosphere soil pH, available nutrients (N, K), and total nutrients (C, N, P, and K) compared with CK and F. Moreover, the soybean root length, surface area, volume, and exudates increased with biochar amendment. In particular, biochar significantly increased the nodule number, dry weight, and nitrogenase activity of soybean. Furthermore, biochar promoted soybean growth and increased soybean yield. In general, we found that the soybean yield increased with biochar and that biochar had a positive, sustainable effect on soil properties and soybean root growth, providing a new cultivation measure for soil health and soybean production in continuous cropping, which is very important for increasing soybean productivity to break the limitations of soybean traditional continuous cultivation. Full article

The must used to make sparkling wine has a low pH value and moderate sugar content, and its potassium content can have a strong influence. An excess of potassium often leads to an insufficient supply of magnesium, since potassium has a strong antagonistic effect on magnesium, and, consequently, to poorer photosynthesis and a poorer quality of the must. The aim of this study was to determine whether the application of foliar fertilizers based on magnesium, phosphorus, and amino acids could reduce leaf potassium content, affecting the reductions in sugar content and pH value and increasing the total acidity of the must. A fertilizer trial with three replicates was conducted on the cultivar Istrian Malvasia (TCtrl—NPK, TMg—NPK + Agromag (6% MgO), TMgP—NPK + Agromag + Fosforo (30% P₂O₅) i TMgPBS—NPK + Agromag + Fosforo + Bio Prot) in a random complete block design. The NPK fertilizer was applied in the autumn. Foliar fertilization was applied three times during the growing season (31 May, 7 July, and 22 August 2014), and leaf samples were collected for leaf analysis before each application. The results show that foliar fertilization significantly reduced leaf potassium content, especially when treated with magnesium alone (treatment TMg). In addition, foliar fertilization significantly lowered the pH and increased the sugar content of the must. The results obtained in this research give a scientific contribution to the creation of fertilizer treatments for vines with a positive effect on the basic chemical composition of the base wine and provide a good basis for further research in reducing the use of certain enological practices during production. Full article

A two-year (2020-21) study was conducted to investigate the possibility of relying of ten-years old pear trees grown on sandy loam soil irrigated by drip on citric acid (CA), gibberellic acid (GA₃) and humic acid (HA). The CA was applied at the concentrations of 500, 1000 and 1500 ppm, GA₃ at 50, 100 and 150 ppm and HA at 3, 4 and 5%, whereas water spray was used as the control. The results of our study proved that CA, GA₃ and HA improved the shoot length, shoot thickness, leaf area and leaf chlorophyll of pear as compared with the control. Moreover, they also positively increased the fruit set percentage and final yield of ‘Le Conte’ pear. The fruit weight, size and firmness were also improved under the influence of aforementioned treatments. The fruit soluble solids, total sugars, leaf nitrogen, leaf phosphorus and leaf potassium of pear were also enhanced as compared with the control. Additionally, spraying of GA₃ at 150 ppm, as well as, HA at 5 and 4% were the superior treatments and showed the most significant impact on plant growth, yield, fruit quality and leaf mineral content of pear. This study provides a basis for the future elucidation of HA-, GA₃- and CA-modulated molecular mechanisms in pear, which can make a significant contribution in the scientific community. Full article

In the current study, the impact of the preceding crops on growth, fresh pod yield, nitrogen fixation efficiency, and nitrogen nutrition of faba bean (Vicia faba L.) was investigated for two years in both organic and conventional crops. As preceding crops served cabbage, pea, and faba bean. The pod number per plant (PN) and the total fresh pod yield (TFPY) were significantly lower with cabbage compared to pea and faba bean as preceding crops in both cropping systems and both experimental years. However, in the organic farming system, pea increased significantly in PN and TFPY compared to faba bean as a preceding crop, while in the conventional system, there was no significant difference between the two legumes. The greater yield performance with the two legumes as preceding crops was associated with higher soil NO₃-N and total-N concentrations at the beginning of the subsequent faba bean crop. The higher soil N availability when the preceding crop was a legume resulted partly from the higher biomass of crop residues left by these crops on the field after harvest, compared to cabbage. However, it was also associated with a more extensive nodulation of the faba bean roots by rhizobia and a higher percentage of N derived from atmosphere (%Ndfa) in their plant tissues, as determined through the natural abundance of the 15N isotope, when the preceding crop was a legume. The cropping system had no impact on pod yield, but organic farming increased the %Ndfa in both years. Full article