Search Results (7,032)

Saline soil represents an important reserve of cultivated land in China, yet poor soil conditions and low-nitrogen use efficiency constrain crop production. Biochar has been widely applied to improve soil properties; however, its interactive effects with nitrogen fertilization in saline soils remain unclear. A pot experiment using coastal saline soil collected from the northern Jiangsu province was conducted to evaluate the combined effects of biochar (0%, 4%, and 8% w·w⁻¹) and nitrogen fertilizer (0, 150, and 200 mg·kg⁻¹) on the growth performance, photosynthetic indices, yield, quality, and nitrogen use efficiency of water spinach (Ipomoea aquatica Forssk.). Moderate biochar application significantly improved vegetative growth of water spinach, as indicated by higher plant height, stem diameter, leaf area index, and SPAD values. In addition, biochar substantially enhanced photosynthetic performance, dry matter accumulation, and yield, whereas excessive biochar or nitrogen application generally inhibited plant performance. The combined application of 4% biochar with 150 mg·kg⁻¹ nitrogen consistently produced the highest yield and nitrogen partial factor productivity, while simultaneously increasing soluble protein, soluble sugar, and vitamin C contents and reducing nitrite accumulation. These research results demonstrated a clear synergistic interaction between biochar and nitrogen fertilization. In coastal saline soils, reducing the usage of nitrogen fertilizer moderately and adding approximately 4% of biochar is an effective strategy. Full article

The excessive use of chemical fertilizers raised concerns regarding environmental sustainability and soil degradation, prompting increasing interest in biofertilizers as eco-friendly alternatives. Among these, a compound that is effective in stimulating root and plant growth is indole-3-acetic acid (IAA). In our study, we evaluated IAA production by the halotolerant bacterium Vreelandella titanicae under different and varying nutritional conditions, such as tryptophan availability, temperature, pH, salinity, etc. The bacterium showed significant IAA production under a broad range of conditions and a dependence on the presence of tryptophan for IAA biosynthesis. High salinity (1.0 M NaCl), slightly alkaline pH (8.0–9.0), and temperatures of 34 °C increased IAA production, while optimal growth occurred in the absence of NaCl at a range of temperatures of 25–28 °C, suggesting a stress-responsive regulation of its biosynthesis. Easily metabolizable carbon sources, such as glucose and mannitol, enhanced IAA yield again, whereas additions of 1.0 g L⁻¹ NH₄NO₃ and KH₂PO₄ in the basal medium, poor in these salts, inhibited both the growth of the bacterium and IAA production. Notably, V. titanicae produced relevant amounts of IAA in seawater (24.57 ± 11.28 μg⋅mL⁻¹) when used as growth medium and dairy whey (15.68 ± 2.42 μg⋅mL⁻¹), highlighting its suitability for low-cost and circular bioprocessing strategies. In conclusion, V. titanicae is a promising Plant Growth-Promoting Rhizobacterium (PGPR) candidate for sustainable IAA production and potential application in saline or marginal agricultural soils. Its ability to synthesize IAA in different growth media could allow its exploitation in environmentally friendly bioprocesses. Full article

Surface mulching and nitrogen (N) application are widely used to enhance crop yield and water productivity (WP). However, their combined effects remain unclear. Here, a three-year field experiment was conducted to comprehensively assess the effects of surface mulching (no mulching, B; straw mulching, S; and plastic film mulching, F) and N fertilization (no N application, N0; split application of urea, N1; 1:2 mixture of controlled-release urea and urea, N2) on maize growth, yield, and WP on the Loess Plateau. Application of nitrogen (N) significantly increased evapotranspiration (ET), grain yield, and WP by 4.58%, 176% (from 5215.43 kg ha⁻¹ in N0 to 14,548.21 kg ha⁻¹ in N2), and 166% (from 11.36 kg ha⁻¹ mm⁻¹ in N0 to 30.63 kg ha⁻¹ mm⁻¹ in N2), respectively. Compared with B and S, F increased ET during the pre-silking stage by 16.75% and 23.99%, respectively, and shortened the vegetative period of maize by 3–9 days but extended the duration from the milky stage (R3) to physiological maturity (R6) in the reproductive period by 5–13 days. F significantly increased yield and WP by 9.18% and 8.26% compared with S. Under F combined with N application, deep soil water (100–200 cm) consumption during R1–R3 increased by 15.75 mm and 13.15 mm compared with B and S, respectively. The combination of F and N2 achieved the highest yield (15,648.28 kg ha⁻¹) and WP (32.44 kg ha⁻¹ mm⁻¹) without causing detectable depletion of soil water within the 0–200 cm profile during the study period, providing an effective strategy for enhancing crop yield and improving water–fertilizer use efficiency in semi-arid regions. Full article

The addition of inhibitors and organic materials in corn fields is an important measure to ensure yield and improve soil fertility. Understanding the effects of the addition of inhibitors and organic material on soil microbial carbon use efficiency (CUE) and microbial mechanisms is crucial for promoting carbon (C) sequestration in agricultural systems. This study explored the effects of the addition of inhibitors (N-(nbutyl) thiophosphoric triamide (NBPT) and 3,4-dimethylpyrazole phosphate (DMPP)) and organic materials (corn stalks and pig manure (PM)) on soil microbial CUE through a field experiment with the continuous addition of inhibitors, corn stalks, and PM incorn fieldss for 7 years. Overall, the application of inhibitors reduced soil microbial CUE by 39.20% by reducing microbial immobilization C and promoting microbial respiration, but did not affect the microbial community structure. Under inhibitor application conditions, the addition of PM improved soil microbial CUE by 37.38%, which was mainly achieved by increasing microbial immobilization C, fungal, and bacterial copies. Long-term addition of organic materials and fertilizers was beneficial to the increase in soil microbial CUE, because the input of nutrients stimulates microbial growth. Although high soil microbial CUE was beneficial to soil C sequestration, it also required appropriate exogenous organic matter addition to ensure soil organic carbon (SOC) increase. In this study, when fertilizer-containing inhibitors were used, combined application with PM was beneficial to improve soil microbial CUE and promote SOC sequestration. Full article

The reliable quantification of urea in agricultural systems requires methods that combine metrological rigor with low environmental impact. This work develops and validates a micro-Raman method (λ = 532 nm) for the direct determination of urea in aqueous solutions and soils. The method is formally compared with the reference procedure ISO 19746:2017 (HPLC). Calibration, based on the 1000–1200 and 1460–1670 cm⁻¹ windows, showed near-ideal linearity in the 0.25–25% w/w range (r² = 0.9999). LOD and LOQ values were 0.178 and 0.735% w/w, respectively. Intra- and inter-day accuracy proved adequate for routine use (RSD ≤ 5%). A one-way ANOVA (p = 0.983) confirmed no statistically significant differences between concentrations obtained by micro-Raman and ISO 19746:2017. In the soil matrix, recoveries ranged between 94 and 101, and the contained biases demonstrate good tolerance to matrix effects. Application to maize plots allowed for monitoring urea disappearance at three depths (0–2 cm, 5–7 cm and 10–15 cm) over 90 days. These differentiated areas of rapid surface hydrolysis from more persistent fractions at depth. The Eco-Scale (96), GAPI (pictogram dominated by green areas), and AGREE (0.88) metrics confirm a significantly lower environmental footprint than that of the chromatographic method. The proposed micro-Raman methodology is emerging as a green, fast, and traceable alternative for monitoring urea in fertilizers and agricultural soils. Full article

Efficient nitrogen (N) management is essential for sustaining crop productivity while minimizing environmental impacts associated with excessive fertilizer use. Variable-rate application (VRA) offers a precision-based approach to matching N inputs with crop demand, yet winter wheat responses to reduced N rates are still underexplored. This study evaluated winter wheat (Triticum aestivum L.) performance under variable and uniform N application strategies using canopy greenness (NDVI), grain yield, plant N content, nitrogen use efficiency (NUE), and fertilizer costs as indicators. Reduced N treatments (40% and 60% VRA rates) were compared with a uniform (100%) application. Canopy greenness increased across all treatments over time, with NDVI values ranging from 0.855 early in the season to approximately 0.94 at later growth stages, and statistically significant among N rates (p < 0.05). Grain yield was highest under the low N rate (1676.81 kg ha⁻¹), although yield differences among treatments were not statistically significant (p > 0.05). Similarly, plant N content varied slightly across treatments, ranging from 1.73% to 1.82%, with no significant differences. In contrast, NUE declined sharply with increasing N rates, decreasing from 71% under the lower rate to 28% under the uniform rate. Overall, variable-rate treatments used just over half the fertilizer input and cost of the uniform rate while supporting comparable yield and plant N status. These results prove that VRA can improve nitrogen efficiency and reduce input costs without compromising winter wheat productivity, supporting its practical value for sustainable fertilizer management. Full article

Soil salinization remains a critical constraint on global land sustainability, severely limiting agricultural output and ecosystem resilience. To address this issue, a field trial was implemented to investigate the interactive benefits of vermicompost (VC) and a novel soil conditioner derived from coal gasification slag-based soil conditioner (CGSS) in mitigating saline–alkali stress. The perennial forage grass Leymus chinensis, valued for its ecological robustness and economic potential under adverse soil conditions, served as the test species. Five treatments were established: CK (unamended), T1 (CGSS alone), T2 (VC alone), T3 (CGSS:VC = 1:1), T4 (CGSS:VC = 1:2), and T5 (CGSS:VC = 2:1). Study results indicate that the combined application of CGSS and VC outperformed individual amendments, with the T4 treatment demonstrating the most effective results. Compared to CK, T4 reduced soil electrical conductivity (EC) by 12.00% and pH by 5.17% (p < 0.05), while markedly enhancing key fertility indicators—including soil organic matter and the availability of nitrogen, phosphorus, and potassium. Thus, these improvements translated into superior growth of L. chinensis, reflected in significantly greater dry biomass, expanded leaf area, and increased plant height. Additionally, the T4 treatment increased soil microbial richness (Chao1 index) by 21.5% and elevated the relative abundance of the Acidobacteria functional group by 16.9% (p < 0.05). Hence, T4 treatment (CGSS: 15,000 kg·ha⁻¹; VC: 30,000 kg·ha⁻¹) was identified as the optimal remediation strategy through a fuzzy comprehensive evaluation that integrated multiple soil and plant indicators. From an economic perspective, the T4 treatment (corresponding to a VC-CGSS application ratio of 2: 1) exhibits a lower cost compared to other similar soil conditioners and organic fertilizer combinations for saline–alkali soil remediation. This study not only offers a practical and economically viable approach for reclaiming degraded saline–alkali soils but also advances the circular utilization of coal-based solid waste. Furthermore, it deepens our understanding of how integrated soil amendments modulate the soil–microbe–plant nexus under abiotic stress. Full article

Soil salinization severely constrains crop productivity and ecosystem services in arid regions. While the application of soil amendments represents a promising mitigation strategy, it remains uncertain whether this practice can effectively enhance soil quality index (SQI), crop productivity, and ecosystem service value (ESV) in saline–alkali farmlands. To address this, a three-year field experiment was conducted to analyze the effects of different amendments (rotary-tilled straw return (RT), plowed straw return (PL), biochar (BC), desulfurized gypsum (DG), DG combined with organic fertilizer (DGO), and an unamended control (CK)) on SQI, sunflower productivity, and ESV in a saline–alkali farmland of arid Northwest China. Results indicated that the BC treatment significantly reduced bulk density by 5.1–7.6% and increased porosity by 6.3–8.3% compared to CK. Both BC and DGO significantly increased soil organic matter and available nutrients while reducing saline ions (HCO₃⁻, Cl⁻, Na⁺), which reduced soil salinity by 21.2–33.6% and 19.9–26.5%, respectively. These synergistic improvements enhanced the SQI by 76.8% and 74.1% for BC and DGO, respectively, relative to CK. Correlation analysis revealed strong positive relationships between SQI and crop nitrogen uptake and yield. Accordingly, BC and DGO increased nitrogen uptake by 74.9–129.0% and yield by 12.2–45.2%, with BC offering more stable benefits over time. Furthermore, BC increased the values of agricultural product supply, nutrient accumulation and climate regulation, thereby increasing the total ESV by 13.7–53.9% relative to CK. In summary, BC and DGO are effective strategies to synergistically enhance soil quality, crop productivity, and ecosystem services in saline–alkali farmlands of arid regions. Full article

To address the challenge of imprecise detection and control of fertilizer application rates caused by high granular flow during fertilization operations, a parallel diversion detection method with real-time application rate regulation is proposed. The mechanism of uniform distribution of discrete particles formed by high-throughput aggregated granular fertilizer was elucidated. Key components including the uniform fertilizer tube, sensor detection structure, six-channel diversion cone disc, and fertilizer convergence tube underwent parametric design, culminating in the innovative development of a six-channel parallel diversion detection device. A multi-channel parallel signal detection method was studied, and a synchronous multi-channel signal acquisition system was designed. Through calibration tests, relationship models were established between the measured flow rate of granular fertilizer and voltage, as well as between the actual flow rate and the rotational speed of the fertilizer discharge shaft. A fuzzy PID control model was constructed in MATLAB2023/Simulink. Using overshoot, response time, and stability as evaluation metrics, the control performance of traditional PID and fuzzy PID was compared and analyzed. To validate the control system’s precision, device performance tests were conducted. Results demonstrated that fuzzy PID control reduced the time required to reach steady state by 66.87% compared to traditional PID, while overshoot decreased from 7.38 g·s⁻¹ to 1.49 g·s⁻¹. Divergence uniformity tests revealed that at particle generation rates of 10, 20, 30, and 40 g·s⁻¹, the coefficient of variation for channel divergence consistency gradually increased with rising tilt angles. During field operations at 0–5.0° tilt, the coefficient of variation for channel divergence consistency remained below 7.72%. Bench tests revealed that the fuzzy PID control system achieved an average accuracy improvement of 3.64% compared to traditional PID control, with a maximum response time of 0.9 s. Field trials demonstrated detection accuracy no less than 92.64% at normal field operation speeds of 3.0–6.0 km·h⁻¹. This system enables real-time, precise detection of fertilizer application rates and closed-loop regulation. Full article

Wolbachia is an endosymbiotic bacterium widespread in invertebrates that causes various reproductive effects, including cytoplasmic incompatibility, feminization, male killing, and the induction of parthenogenesis (PI). PI-Wolbachia wRem converts Telenomus remus, an egg parasitoid of Spodoptera frugiperda, from arrhenotokous reproduction (male-producing) to thelytokous reproduction (female-producing). Long-term symbiosis between egg parasitoids and Wolbachia has been shown to lead to reproductive barriers and “female functional virginity,” causing progressive and potentially irreversible sex ratio imbalances. However, whether such reproductive barriers occur in T. remus remains unknown, which has important implications for biological control programs utilizing this parasitoid. To address this question, we cured wRem using tetracycline and conducted crossing experiments with naturally uninfected strains (W-). The results indicated that the cured strain (Wcure) retained normal sexual reproductive capability, with self-crossing fertilization rates comparable to those of W- strains. However, first-generation hybridization between Wcure and W- strains produced strongly male-biased offspring (male proportion: 94.3% and 85.8% for W-♂ × Wcure♀ and Wcure♂ × W-♀, respectively), indicating substantial reproductive incompatibility. Notably, an asymmetric pattern was observed between reciprocal crosses. In second-generation hybridization experiments, hybrid females (W-/Wcure) mated with W- or Wcure males showed markedly recovered sex ratios (male proportion: 14.3% and 15.6%, respectively), although total offspring numbers remained lower than in self-crossing groups. These results suggest that the reproductive incompatibility in T. remus differs from female functional virginity and is more consistent with mitonuclear incompatibility arising from population divergence. The partial recovery in second-generation hybrids indicates that surviving F1 hybrid females likely represent individuals selected for compatibility, rather than exhibiting progressive deterioration of sexual function. These findings offer insights into Wolbachia’s impact on parasitoid reproduction and highlight key considerations for biological control applications, underscoring the importance of evaluating reproductive barriers before deploying cured strains and preventing symbiont loss within populations. Full article

Apple cultivation faces soil acidification and pollution due to excessive fertilization, compounded by a scarcity of potassium (K) fertilizers. Polyhalite, a natural multi-nutrient mineral, offers a potential sustainable alternative. Therefore, a three-year field experiment was conducted, comprising a no-potassium control (CK), two conventional potassium fertilizers (sulfate of potash-based and muriate of potash-based), and six polyhalite compound fertilizer treatments (with different basal and topdressing strategies), to evaluate their effects on apple growth and soil fertility. Results showed that the single topdressing application of potassium chloride-type polyhalite compound fertilizer (T6) achieved the highest yield in the final year, which was 10.11–28.03% higher than the other potassium-applied treatments. It also achieved the highest fruit vitamin C and soluble solids content (9.53 mg 100 g⁻¹ and 13.27%, respectively). The T6 treatment demonstrated the best performance in terms of agronomic efficiency and partial factor productivity of potassium fertilizer, reducing fertilizer waste and loss. Furthermore, the T6 treatment effectively increased soil pH, available potassium, and exchangeable calcium levels, thereby improving soil fertility. Thus, polyhalite proves effective in replacing conventional K fertilizers, with the single topdressing of MOP-type polyhalite compound fertilizer (T6) offering the most comprehensive agronomic and environmental benefits. Full article

Soil organic matter (SOM) is a key indicator for evaluating soil fertility and ecological functions, and hyperspectral technology provides an effective means for its rapid and non-destructive estimation. However, in practical soil systems, the spectral response of SOM is often highly covariant with mineral composition, moisture conditions, and soil structural characteristics. Under small-sample conditions, hyperspectral SOM modeling results are usually highly sensitive to spectral preprocessing methods, sample perturbations, and model architecture and parameter configurations, leading to fluctuations in predictive performance across independent runs and thereby limiting model stability and practical applicability. To address these issues, this study proposes a multi-strategy collaborative deep learning modeling framework for small-sample conditions (SE-EDCNN-DA-LWGPSO). Under unified data partitioning and evaluation settings, the framework integrates spectral preprocessing, data augmentation based on sensor perturbation simulation, multi-scale dilated convolution feature extraction, an SE channel attention mechanism, and a linearly weighted generalized particle swarm optimization algorithm. Subtropical red soil samples from Guangxi were used as the study object. Samples were partitioned using the SPXY method, and multiple independent repeated experiments were conducted to evaluate the predictive performance and training consistency of the model under fixed validation conditions. The results indicate that the combination of Savitzky–Golay filtering and first-derivative transformation (SG–1DR) exhibits superior overall stability among various preprocessing schemes. In model structure comparison and ablation analysis, as dilated convolution, data augmentation, and channel attention mechanisms were progressively introduced, the fluctuations of prediction errors on the validation set gradually converged, and the performance dispersion among different independent runs was significantly reduced. Under ten independent repeated experiments, the final model achieved R² = 0.938 ± 0.010, RMSE = 2.256 ± 0.176 g·kg⁻¹, and RPD = 4.050 ± 0.305 on the validation set, demonstrating that the proposed framework has good modeling consistency and numerical stability under small-sample conditions. Full article

The phaeozem in Northeast China is rich in soil organic carbon (SOC). However, the excessive and inefficient application of chemical fertilizers, particularly nitrogen fertilizers, has primarily led to a decrease in soil pH in this region. Currently, the relationship between soil pH and the stability of soil organic carbon (SOC) remains ambiguous. This study, conducted over 13 years of field experiments, focused on soils exhibiting varying degrees of pH resulting from different nitrogen application rates. The research employed aggregate classification, ¹³C nuclear magnetic resonance spectroscopy, and analysis of microbial community composition to investigate the alterations in the SOC stabilization mechanisms under varying nitrogen application levels. Our results demonstrated that the decline in soil pH led to reductions in macroaggregates (>2 mm) and the soil aggregate destruction rate (PAD) by 4.8–14.6%, and in soil aggregate unstable agglomerate index (E_LT) by 9.7–13.4%. The mean weight diameter (MWD) and geometric mean diameter (GMD) exhibited significant declines (p < 0.05) with decreasing pH levels. According to the ¹³C NMR analysis, the SOC was predominantly composed of O-alkyl carbon and aromatic carbon. At a pH of 5.32, the Alip/Arom values decreased, while the molecular structure of SOC became more complex under different levels of pH. In addition, the increase in [Fe(Al)-OC] (31.4–71.9%) complex indicates a shift in the stability of organic carbon from physical protection to organic mineral binding. Declining soil pH significantly reduced the diversity of soil microbial communities and promoted a shift toward copiotrophic microbial groups. Overall, declining soil pH resulted in a decline in soil aggregate stability and an increase in SOC aromaticity. This drove the shift in the stabilization mechanism of SOC in the black soil ecosystem of meadows in Northeast China from physical protection to chemical stability. Full article

Biochar is known to enhance soil potassium (K) availability and promote plant K uptake; however, its influence on the transformation pathways of fertilizer potassium and the mechanisms regulating crop potassium accumulation remains insufficiently understood. This study conducted a pot experiment using three soil types—Albic, Brown, and Sandy soils—with different biochar application rates (0, 10, and 20 g·kg⁻¹) in combination with potassium fertilizer, to systematically evaluate the regulation of soil K forms, K fertilizer transformation rates, K use efficiency, and K uptake and accumulation in soybeans. The results demonstrated that the combined application of biochar and K fertilizer significantly increased the contents of available, water-soluble, exchangeable, and non-exchangeable K across all three soils. At the highest biochar application rate (20 g·kg⁻¹), available K increased by 15.37%, 16.78%, and 11.77% in the Albic, Sandy, and Brown soils, respectively, compared to the control. Furthermore, biochar altered the transformation pathways of fertilizer K; it consistently reduced the conversion rate of fertilizer K into exchangeable K across all soils, redirecting it toward the water-soluble and non-exchangeable K pools, thus functioning as a potassium “scheduling center”. Adsorption–desorption experiments revealed that biochar exhibits a strong multilayer adsorption capacity for K ions, with most of the adsorbed K not easily desorbed, providing mechanistic support for the observed shift in transformation pathways. In terms of K use efficiency, biochar reduced the K of agronomic efficiency (KAE) due to a “dilution effect” from its inherent K content. Under the high application rate (20 g·kg⁻¹), the KAE decreased by 11.79% in Albic soil, 88.48% in Sandy soil, and 71.73% in Brown soil, while significantly increasing the partial factor productivity of K (PFPK) and apparent recovery efficiency of K (AREK). Ultimately, the co-application of biochar and K fertilizer significantly enhanced total K accumulation and seed yield in soybeans by increasing K concentrations in various plant parts and promoting dry matter accumulation. At the biochar application rate of 20 g·kg⁻¹, the potassium accumulation and soybean yield under biochar treatment reached maximum increases of 70.77% (in Brown soil) and 42.63% (in Albic soil), respectively. This study demonstrates that biochar can synergistically reduce potassium (K) leaching and improve fertilizer use efficiency by regulating K transformation pathways. This provides a practical guideline for utilizing biochar as a dual-function amendment, which acts as both a supplemental K source and a soil conditioner, thereby supporting the development of more sustainable potassium management practices in diverse cropping systems. Full article

Fertilization management is crucial mainly during the walnut training phase in order to obtain good plant formation, which is essential for guaranteeing future optimal yield. The aim of the present experiment was to evaluate the effect of different organic amendments on plant nutritional status and soil fertility in young bearing walnut trees. The experiment was conducted in 2023 and 2024 on walnut trees of the cultivar Chandler grafted on Juglans regia, planted in 2021. Since 2023, plants were yearly treated as follows: 1. non-fertilized control; 2. mineral fertilization; 3. application of municipal solid waste compost; and 4. application of compost from agri-food chain scraps. Soil amendments were supplied at the same rate as mineral fertilizer (120 kg N ha⁻¹) in spring on the tree row on a 1.5 m wide strip, while mineral fertilizer was split in two applications (50% in spring and 50% in summer). Plant growth, measured with trunk diameter and pruning wood weight, was enhanced by mineral fertilization, followed by compost, in comparison to the control. Soil mineral N was too high in relation to plant needs, with a consequent increase in the risk of nitrate leaching. Organic amendments increased soil nutrient availability, microbial activity, and carbon concentration, which, in the long term, could provide a positive environmental effect related to its sequestration into the soil. Full article