Search Results (615)

Low soil nutrient availability and uptake negatively affect crop productivity in acidic soils. For example, phosphorus (P) availability is reduced by fixation of aluminium (Al) and iron (Fe) hydrous oxides and precipitation with soluble Al and Fe. In addition, soil acidity inhibits root growth, and application of agricultural lime ameliorates these challenges, thereby improving yields. However, resource-limited farmers in the Eastern Cape Province can rarely afford to procure lime and chemical fertilisers, which necessitates alternative approaches to addressing the challenge of low nutrient availability for crops. The present study explores interactions between cattle manure and mineral fertiliser applications coupled with arbuscular mycorrhizal fungi (AMF) inoculation on the agronomic performance of Amaranthus grown in acidic soil. The treatments were 100% cattle manure, 50% cattle manure + 50% NPK fertiliser and lime, 33% cattle manure + 33% NPK and lime + AMF, the recommended rate of mineral fertiliser and lime, AMF, and an absolute control. Cattle manure and mineral fertiliser application, including mixtures of their microdoses, coupled with AMF inoculation, significantly improved the growth and yield of Amaranthus species. Leaf tissue concentrations of N, P, K, Ca, Mg and Zn and their uptake, and selected residual soil properties and nutrients increased significantly following application of the treatments relative to the unfertilised control. The findings of this study imply that application of manure and mixtures of microdoses and mineral fertiliser, together with AMF, improve nutrient uptake and yield of Amaranthus and residual nutrients that benefit subsequent crops. Full article

The rhizosphere, a confined area of soil plant roots, is an intersection of microbial activity and root exudates. Known as the rhizosphere effect, it enhances crop yield and sustainability by improving nutrient availability, beneficial compounds, and pathogen control. This study combines a field-based rhizosphere–bulk soil comparison for peanut with a geostatistical approach to quantify the spatial variability of rhizosphere-driven changes in soil quality indicators in the Ghardaïa region (southern Algeria), which is known for its sandy–clay and sandy–loam soils. Samples of rhizosphere and bulk soils were prospected using a systematic plan. Subsequently, the pH, electrical conductivity, calcium carbonate, organic matter, total nitrogen, available phosphorus, total potassium, and soluble sodium were determined for each soil (rhizosphere and bulk soil). To assess the spatial variability of rhizosphere soil parameters, semi-variograms of the fitted models were generated using auto-kriging. The results showed that both types of soils were moderately alkaline, with a reduction of 5.52% in the pH of the rhizosphere compared to the bulk soils. Soils were relatively low in organic matter, with only 3.3% of soils having organic matter levels above 20 g kg⁻¹. However, organic matter contents were consistently higher in the rhizosphere (8.51 ± 4.59 g kg⁻¹) than in the bulk soil (6.78 ± 3.52 g kg⁻¹). In the rhizosphere, an increase of 10% in labile phosphorus was noted. Total nitrogen was increased by 52.57%. T-tests suggested no significant difference in potassium and sodium levels, and they were moderately present in both soils. Significantly positive relationships were noted between available phosphorus and total nitrogen (R = 0.59, p < 0.001). However, negative correlations were revealed between pH and organic matter available phosphorus (R = −0.77, p < 0.001) and pH and total nitrogen (R = −0.56, p < 0.01). These results indicate the effects of rhizosphere interactions on soil property improvements and their implications for sustainable agricultural practices, including crop rotation, intercropping, and green manure applications. Full article

Identifying plant-growth-promoting rhizobacteria tolerant to saline–alkali conditions is critical for developing effective microbial agents and multi-strategy approaches to remediate saline–alkali soil. Two salt–alkali-tolerant bacterial strains—phosphorus-solubilizing Bacillus pumilus JL-C and cellulose-decomposing B. halotolerans XW-3—were isolated from saline–alkali soil, with both exhibiting multiple plant-growth-promoting properties, including nitrogen fixation and the generation of indole-3-acetic acid, siderophores, and 1-aminocyclopropane-1-carboxylate deaminase. Alfalfa pot experiments were conducted under four treatments: a control, the strain JL-C treatment, the strain XW-3 treatment, and a co-inoculation treatment (JL-C/XW-3), all mixed with corn straw and applied to the saline–alkali soil. The results demonstrated that the co-inoculation treatment yielded the most significant growth-promoting effects on alfalfa, showing enhanced antioxidant enzyme activities; increased contents of proline, soluble sugar, and protein; reduced malondialdehyde content; lowered pH and electrical conductivity; elevated activities of key enzymes; and increased levels of available nitrogen, phosphorus, potassium, and organic matter content in the soil. The pot experiments were confirmed by field experiments. The results of 16S rRNA high-throughput sequencing revealed changes in the bacterial community composition in the alfalfa rhizosphere, showing shifts in the relative abundance of several bacterial taxa often reported as plant-associated or potentially beneficial. This study establishes a combined remediation strategy for saline–alkali soil utilizing complex microbial agents and corn straw. Full article

Soil salinization is a major threat to agricultural sustainability. Poly-gamma-glutamic acid (γ-PGA), a biopolymer produced by microbial fermentation, has received attention as a biostimulant due to its positive effects on crop performance. However, the function of γ-PGA in crop salt stress tolerance and its effect on the rhizosphere are unclear. This study explores the effects of γ-PGA application on rhizosphere soil nutrients and the soil–physical environment and examines the salt tolerance response of maize seedlings grown in saline–alkali soil under such an application regime. The results show a significant promotion of maize seedling growth and of nutrient accumulation with γ-PGA application under salt stress; plant dry weight, stem diameter, and plant height increased 121%, 39.5%, 18.4%, respectively, and shoot accumulation of nitrogen, phosphorus, potassium, and carbon increased by 1.38, 2.11, 1.50, and 1.36 times, respectively, under an optimal-concentration γ-PGA treatment (5.34 mg kg⁻¹ (12 kg ha⁻¹)) compared with the control. γ-PGA treatment significantly decreased rhizospheric pH and soil electrical conductivity and significantly increased nutrient availability in the rhizosphere, especially available nitrogen (AN) and available potassium (AK). Compared with the control, AN, available phosphorus (AP), and AK increased by 13.9%, 7.70%, and 17.7%, respectively, under an optimal concentration treatment with γ-PGA. γ-PGA application also significantly increased the activities of urease, acid phosphatase, alkaline phosphatase, dehydrogenase, and cellulose in rhizosphere soil by 35.5–39.3%, 35.4–39.3%, 5.59–8.85%, 18.9–19.8%, and 19.2–47.0%, respectively. γ-PGA application significantly decreased Na⁺ concentration and increased K⁺ concentration in shoots, resulting in a lowering of the Na⁺/K⁺ ratio by 30.5% and an increase in soluble sugar and soluble protein contents. Therefore, rhizosphere application of water-soluble and biodegradable γ-PGA facilitates the creation of an optimized rhizospheric environment for maize seedling and overcomes osmotic and ionic stresses, offering possibilities for future use in drip-irrigation systems in the cultivation of crops on saline-alkali land. Full article

Argania spinosa L. Skeels is an ecological pillar of the arid zones of South-West Morocco, currently threatened by the drastic climate change. This study investigates the effect of the combined application of compost (C) and subsurface water retention technology (SWRT) on field performances of one-(1Y) and two-year-old (2Y) argan seedlings. A randomized field trial was performed with four treatments: Control, C, SWRT, and C + SWRT. We evaluated soil properties, growth, and physiology, alongside biochemical parameters including stress markers, compatible solutes, antioxidant enzyme activities, and secondary metabolites. The results reveal the significant effect of C and/or SWRT on argan seedlings performances, particularly in 1Y subjects. The C + SWRT strongly stimulated stem elongation (246% vs. 163%), stomatal conductance (75% vs. 99%), photosynthetic efficiency (18% vs. 11%), and chlorophyll a content (80% vs. 65%) in 1Y and 2Y seedlings, respectively, compared to their corresponding controls. Under the same treatment, malondialdehyde levels were significantly reduced by 37% in 1Y seedlings and 23% in 2Y seedlings. In addition, catalase activity and soluble sugar, protein, and polyphenol content increased by 38, 43, 26, and 21%, respectively, in the younger seedlings and by 53, 51, 18, and 19%, respectively, in the elder seedlings. In terms of soil health, C + SWRT significantly enhanced total organic carbon and matter, available phosphorus, and reduced electrical conductivity. In summary, the C + SWRT application significantly improved argan plant performances, with a particularly marked effect on 1Y seedlings, which makes this combination an alternative solution to enhance the resilience of the argan tree in the era of climate change and promote the success of the reforestation program. Full article

The disposal of phosphogypsum has emerged as a significant challenge for the phosphorus chemical industry in China in recent years. Utilizing phosphogypsum in alkali-activated materials represents an effective approach to valorize this byproduct. The alkali modulus is a critical parameter affecting the performance characteristics of phosphogypsum-based alkali-activated materials. This study aims to investigate the effects of the alkali modulus on the early-age properties (setting time, fluidity, flexural strength, and compressive strength) and hydration mechanisms of slag–phosphogypsum composite alkali-activated materials (HSFP) across various slag–phosphogypsum–fly ash systems, thereby identifying the optimal alkali modulus. The findings demonstrate that an alkali modulus of 1.35 optimally enhances the mechanical performance of HSFP. At this specific modulus, the equilibrium between alkalinity and soluble silica availability facilitates complete hydration, resulting in a dense gel-crystal microstructure characterized by the highest C-(A)-S-H gel content (58.2%) after 28 days. The effect of the alkali modulus on mechanical properties is contingent upon the fly ash-to-phosphogypsum (FA:PG) ratio, whereas its effect on fluidity and setting time is negligible. The effect of alkali modulus on the strength of HSFP is significantly affected by the fly ash-to-phosphogypsum (FA:PG) ratio. At an FA:PG ratio of 4:6, the flexural strength initially decreases and then increases as the alkali modulus values increase, while the compressive strength shows a consistent upward trend. At FA:PG ratios of 1:5 and 1:9, the flexural strength increases linearly with the alkali modulus, whereas the compressive strength first rises and then experiences a slight decline. These results offer both theoretical insights and practical guidance for the optimization of phosphogypsum-based cementitious material formulations, thereby supporting their potential for large-scale application. Full article

Aiming at the problems of tree vigor decline and unstable fruit quality caused by soil impoverishment and easy nutrient loss in the Ziziphus jujuba Mill. ‘Huizao’ (Huizao) producing areas of southern Xinjiang, the application effect of bag-controlled slow-release fertilizer (BCSRF) in this region remains unclear. In this study, a field experiment was conducted with four fertilization concentration gradients, including CK (0 kg/ha), T1 (22 kg/ha), T2 (44 kg/ha), and T3 (66 kg/ha), to investigate the effects of BCSRF on soil nutrient dynamics and plant growth, as well as the fruit yield and quality of Huizao. The results showed that BCSRF could effectively maintain the supply levels of soil alkali-hydrolysable nitrogen, available phosphorus, and available potassium during key growth periods, among which the T3 treatment exhibited the most significant effect. This treatment not only significantly increased the yield per plant of Huizao by 39.34% compared with the control, but also markedly enhanced the contents of the endogenous substance, including soluble sugar and cyclic adenosine monophosphate. This study confirms that under the condition of sandy loam soil in southern Xinjiang, a single basal application of an appropriate amount of BCSRF can achieve continuous nutrient supply, simultaneously improve soil fertility and fruit quality, providing a theoretical basis and technical guidance for simplified and efficient fertilization in local jujube orchards. Full article

In the context of climate change, alterations to the physico-chemical properties of soils, particularly in Mediterranean regions, are a growing source of preoccupation. This study analyzes the ecological plasticity and biochemical adaptability of Thymus saturejoides to changes in soil physico-chemical properties in four contrasting environments in Morocco’s western High Atlas (TM: Tidili msfioua, SF: Sti fadma, TA: Taouss, TN: Tisi ntast). It highlights the influence of edaphic characteristics on the physiology and metabolic composition of the species, revealing marked soil heterogeneity between sites. The results for the physico-chemical characteristics of the soil revealed marked heterogeneity between sites. Tisi ntast and Taouss soils had the highest values in terms of electrical conductivity (TN: 0.25 dS/m, TA: 0.18 dS/m), available phosphorus (TN: 18.58 ppm and TA: 26.06 ppm) and total nitrogen (TN: 0.27% and TA: 0.14%), associated with a silty texture, suggesting higher fertility. Conversely, the soil at the TM site was characterized by low total nitrogen content (0.09%), a high C/N ratio (24.4) and a sandy-silty texture, indicating more constraining conditions for plant growth. From a physiological standpoint, plants from the TA site had the lowest chlorophyll levels (17.10 mg g⁻¹FW), while those from the TN site showed the highest levels (31.08 mg g⁻¹FW), accompanied by increased protein content and reduced polyphenol oxidase and peroxidase. In contrast, TM plants showed significant accumulation of total soluble sugars (30 mg g⁻¹FW), proline (22.53 µmol g⁻¹FW), hydrogen peroxide (1.33 nmol g⁻¹FW) and malondialdehyde (62.97 nmol g⁻¹FW), reflecting strong activation of oxidative stress responses. On the other hand, plants from the TA site displayed significantly lower levels of these stress markers compared to other sites, suggesting greater physiological resilience. These results highlight the pivotal role of interactions between edaphic and environmental conditions in modulating plant physiological and biochemical responses, shedding light on the ecological adaptation mechanisms of plant species to the contrasting ecosystems of the Western High Atlas. Full article

Phosphorus (P) is an essential nutrient in plant development, but its availability in the soil is often limited due to chemical fixation and poor solubility. This study presents the development, characterization and evaluation of a novel granular bioinoculant formulated with Aspergillus tubingensis (P-solubilizing) and Trichoderma virens (P-mineralizing) using clinoptilolite (CZ) as a carrier to improve P bioavailability. The formulation process included the evaluation of the proposed components, the standardization of conidia production in different media cultures and conditions, the elaboration and characterization of the bioinoculant and its evaluation in plants. In this study, in vitro analysis demonstrated the synergistic effect of the components, showing that in all treatments with dual inoculation and CZ, the amount of soluble phosphorus (SP) was higher than in their counterparts (from 27.8 to 36.8 mg·L⁻¹). A concentration greater than 1 × 10⁹ CFU·mL⁻¹ was obtained by standardizing the production of conidia in different media (PDA, V8-Agar and Molasses Agar), which were then used to produce granular batches containing at least 2 × 10⁷ CFU·g⁻¹. Furthermore, the size (88% of the granules measured <4.5 mm), purity (<2 CFU·g⁻¹ in 10⁻⁴ dilution), and moisture content of the prototype granules (3.3–3.8%) were confirmed to be within established international quality parameters. Plant evaluations in chili and tomato demonstrated the formulation efficacy, showing an increase in both soluble and foliar P content (with at least 30% more than controls), alongside improvements in all parameters evaluated that are related to plant growth promotion (with at least 15% more growth than controls). The development of this formulation prototype represents a focused effort toward process standardization and optimization required to validate developed formulations, thus promoting the advancement of applied biotechnology. Full article

Phosphate-solubilizing microorganisms (PSMs) show promise for sustainable agriculture, yet inconsistent field performance limits their application. We investigated phosphate solubilization mechanisms in Enterobacter ludwigii strains GMG278, GMG291, GMG378 and Enterobacter soli GMG1156 through greenhouse wheat experiments, high-performance liquid chromatography (HPLC) organic acid analysis, and comparative genomics. Greenhouse trials demonstrated that bacterial inoculation compensated for phosphorus deficiency, with GMG291, GMG1156, and GMG278 showing superior performance. HPLC identified malic acid as the predominant secreted organic acid, with E. soli producing threefold higher concentrations than E. ludwigii strains. Phosphate solubilization efficiency followed the order FePO₄ > AlPO₄ > Ca₃(PO₄)₂, with maximal release (95.9–97.7 μg/mL) from iron phosphate despite lower malic acid secretion, suggesting siderophore involvement. An inverse correlation between malic acid levels and soluble phosphate concentrations likely reflects competitive bacterial phosphate uptake and secondary precipitation processes. Comparative genomics revealed missense mutations in the LuxR transcriptional regulator of strain GMG378 (Asp86Asn and Arg97Leu) near predicted DNA-binding domains, correlating with reduced solubilization capacity. Phosphate solubilization in Enterobacter proceeds primarily through metal–malic acid complex formation, with strain-specific efficiency linked to LuxR-regulated biofilm formation genes. These findings suggest PSM screening should incorporate biofilm-related genetic markers alongside acid production measurements. Full article

This study examined the impact of various treatments on the storage quality of sugar-cored ‘Fuji’ apples, with the objective of establishing a theoretical foundation for extending the retention period of these apples and augmenting their commercial worth. This experiment utilized three distinct treatments for sugar-cored ‘Fuji’ apples, with the combination of 1-methylcyclopropene and polyethylene self-sealing bag treatment (1-M+PE) demonstrating the most effective prolongation of the storage duration for the sugar-cored apples. The 1-M+PE treatment significantly mitigated the reduction of sugar-cored in ‘Fuji’ apples and extended the onset of cellular rupture, postponing the loss of firmness and preserving the concentrations of sorbitol and sucrose throughout the storage duration. The 1-M+PE treatment effectively prolonged the storage duration of sugar-cored apples in cold storage. ‘Fuji’ apples subjected to 1-M+PE treatment were stored in cold storage for 120 days. The sugar-cored apple rate was 38.9%. The firmness was 14.8% greater than that of the control group. The soluble solid concentration in the sugar-cored part was 3.83% higher than that of the control group. The reducing sugar content in the sugar-cored part was 16.2% higher than that of the control group, and the titratable acid content in the sugar-cored part was 1.86 times greater than that of the control group. The correlation study of the indicators during the storage period revealed a robust association between the rate of sugar-cored apple and the content of sorbitol, potassium, phosphorus, and calcium. Experimental findings demonstrate that the concurrent application of 1-M+PE significantly inhibits the disappearance of sugar-cored. Full article

There are large amounts of carbohydrates and proteins in rban perishable organic waste (UPOW), which can be converted to short chain fatty acids (SCFAs) through microbial methods. In this study, the mass balance and properties of organic slurry generated from UPOW pretreatment were investigated first. Then, the optimal conditions for SCFAs production from organic slurry of UPOW was studied. It was found that under the conditions of pH 8 ± 0.5 and reaction time of 3 d, the yield of SCFAs, mainly composed of acetic and propionic acids, in the full-scale reactor was 0.68 gCOD/gTCOD of organic slurry. Under the conditions of influent NH₄⁺-N, total nitrogen, soluble ortho-phosphorus, and soluble COD of 27–39, 33–45, 2–9, and 220–300 mg/L, respectively, the use of SCFAs-enriched fermentation liquid (100 mg COD/L) as the additional carbon source for full-scale biological municipal wastewater treatment showed a higher total nitrogen and phosphorus removal efficiency than that of sodium acetate (88.1 ± 5.2% against 81.4 ± 4.5% and 96.9 ± 3.1% versus 91.5 ± 2.8%) due to greater key enzyme activity and short-cut nitrification and denitrification capacity. Finally, based on the actual operation process, an economic benefit analysis on the production of SCFAs-enriched fermentation liquid from UPOW was conducted, and the issues that need to be addressed for the promotion and application of this technology were discussed. This study contributes to achieving sustainable synergistic treatment of organic waste and wastewater. Full article

The use of Bacillus spp. in combination with mineral fertilizers represents a sustainable alternative to conventional agricultural practices. This study evaluated the effects of inoculation with Bacillus amyloliquefaciens BV03 (Ba) on corn fertilized with phosphorus (P) sources of different solubilities. Two experiments were conducted under greenhouse conditions in a completely randomized design, following a 2 (without and with Ba) × 4 [control (without P, –P), triple superphosphate (TSP), Bayóvar natural phosphate (BNP), and Pratápolis natural phosphate (PNP)] factorial arrangement. Plant growth parameters, chlorophyll a fluorescence, gas exchange, photosynthetic pigments, nutritional status, biomass accumulation, and grain yield were assessed. Corn responses to Ba inoculation varied with P source and season. Inoculation with Ba, Ba + TSP, and Ba + BNP at sowing enhanced biometric traits (height, stem diameter, and leaf area); physiological parameters (F_v’/F_m’, ΦPSII, ETR, E, g_s, WUE); biochemical variables (Chl a, Chl b, and carotenoids); nutritional contents (N, P, K, Ca, and Mg); and yield traits. Overall, our results highlight the potential of Bacillus amyloliquefaciens BV03, alone or in combination with triple superphosphate or Bayóvar natural phosphate, as a sustainable alternative for phosphorus fertilization to improve corn growth and development. Full article

Accurate evaluation of plant-available phosphorus (P) in flooded paddy soils requires consideration of redox dynamics and soil-specific properties. This study evaluated five soil P extraction methods, such as Truog, Bray 2, Mehlich 3, Olsen, and ascorbic acid-reduced Bray 2 (AR Bray 2), using soils collected from 20 paddy fields in a cold region of Japan that have received long-term fertilization. All four methods, except AR Bray 2, were conducted under air-dried and flooded incubation conditions. Additionally, we conducted pot experiments with the two rice cultivars to measure P uptake. Bray 2 extracted the highest amount of P (543.6–1045.4 mg P kg⁻¹). Incubation increased extractable P by factors of 2.4–4.9 with the Mehlich 3 and Truog methods, indicating enhanced P solubility under reduced conditions. The Olsen method showed minimal sensitivity to redox changes (−31.4 mg P kg⁻¹). Principal component and cluster analyses suggested three patterns of soil P behavior under changing redox conditions: (1) stable P extractability regardless of redox status; (2) increased P availability after incubation; and (3) P extractability depending on the extraction method used. These patterns were not explained by regional or taxonomic classifications. A comparison of soil extractions and P uptake indicated that no single method consistently predicted shoot P concentrations across all soils, suggesting that conventional P extraction methods may have limited ability in long-term fertilized paddy soils. Our findings demonstrate that soil-specific redox behavior and cultivar-specific P demand critically influence the effectiveness of standard P tests. Therefore, selecting diagnostic methods tailored to soil characteristics and crop requirements is essential for accurate P evaluation and sustainable fertilizer management in rice cultivation. Full article

Eucalypt plantations form the basis of Brazilian forestry; however, successive rotations under coppice systems often experience productivity declines. This study presents an original long-term investigation over a 13-year cultivation cycle (2005–2018) with Eucalyptus grandis W. Hill ex Maiden × E. urophylla S. T. Blake, assessing whether the full maintenance of nine phosphate fertilization packages could sustain productivity from the first to the second rotation in a commercial plantation in Itamarandiba, Minas Gerais. Continuous forest inventories and rotation-specific growth modeling were used. Productivity in the second rotation declined by 33%–46% in packages TP1 to TP6, which included various phosphorus sources, highlighting the recurring challenges of coppice systems. Conversely, the highest and most consistent yields (~305 m³ ha⁻¹ rotation⁻¹) were obtained with package TP9, which consisted of 280 kg ha⁻¹ of triple superphosphate (TSP) applied at the beginning of each rotation and 600 kg ha⁻¹ of ammonium sulfate (SA) in split topdressing applications. These findings demonstrate that the full maintenance of fertilization, specifically with highly soluble phosphorus sources combined with balanced nitrogen and sulfur supplementation, is an effective strategy to secure productivity and ensure the economic viability of coppice systems. This offers a new paradigm for managing successive rotations, where nutritional synergy, rather than single-nutrient fertilization, is key to enhancing the resilience of clonal eucalypt plantations. Full article