Search Results (143)

Eutric Regosols are globally important but low-fertility soils with poor nutrient retention, limiting crop productivity and increasing environmental risks. This study evaluated whether combining a moderate reduction in synthetic nitrogen (N) fertilizer with organic manure application could rapidly improve soil fertility, sustain maize yield, enhance nitrogen use efficiency (NUE), and increase yield resilience in these soils. A four-year field experiment was conducted on a purple soil (Eutric Regosol) with five treatments: no N (CK), conventional synthetic N (CN), a 20% synthetic N reduction (OP), and the OP treatment combined with 3000 (OPM1) or 6000 (OPM2) kg ha⁻¹ of organic fertilizer. Maize yield, yield components, NUE indices, soil properties, and net economic benefits (NEB) were measured. OP alone reduced yield by 7.57% compared to CN. OPM2 progressively increased yield, surpassing CN by 12.36% after four years, and indicated greater yield resilience during a high-rainfall year. OPM2 also significantly improved topsoil organic matter (+12.9%), total N (+46.3%), and NUE indices over time. Although initial NEB was lower for organic-amended treatments, OPM2 achieved higher economic returns than CN in the latter two years. Integrating a 20% synthetic N reduction with 6000 kg ha⁻¹ of organic manure is an effective strategy for rapid fertility improvement in Eutric Regosols. This approach compensates for yield reductions from less synthetic N, progressively enhances yield and NUE, improves soil health, increases economic returns, and strengthens buffering capacity against high-rainfall events. Full article

This study established a refined, distributed SWAT modeling framework that integrates elevation-band and snowmelt modules to reconstruct the alpine hydrological and sediment cycles of the Koshi River Basin (KRB) over the period 1990–2024, with climate scenarios constructed using the delta change approach. The KRB, a major transboundary watershed traversing China, Nepal, and India, was selected owing to its critical hydro-climatic role under the destabilizing “Asian Water Tower”; it generates substantial sediment yield, hosts the densest concentration of hydropower potential within the Ganges system, and spans an extreme vertical gradient from Mount Everest to the southern alluvial plains. Results reveal accelerated warming at a rate of 0.21 °C per decade and an overall warming–wetting trend, punctuated by an abrupt interdecadal shift around 2015. Precipitation dominated interannual streamflow variability, with enhanced rainfall triggering basin-wide sediment surges that overwhelmed the natural buffering capacity of the land surface. Conversely, rising temperatures intensified actual evapotranspiration, markedly depleting soil water and reducing total water yield and monsoon runoff, although sustained snow and glacier melt effectively elevated the dry-season low-flow baseline. The integrated climate forcing reshaped the disparity between hydrological extremes, imposing severe seasonal eco-hydrological stress that manifested as a pre-monsoon deficit in terrestrial green water and acute summer sediment outbursts for aquatic habitats. Furthermore, the flood regime exhibited an altered distribution, with mid-to-high frequency floods enhanced while low-frequency extreme flood peaks declined. The hydro-sedimentological regime consequently exhibits pronounced nonlinear responses to climate change, providing a critical, threshold-based scientific foundation for adaptive transboundary water resource management. Full article

Alfalfa (Medicago sativa L.) is widely recognized as a major forage crop, yet its role as a multifunctional biological input in sustainable horticultural production remains underexplored. This review evaluates alfalfa as a biological nitrogen source, organic fertilization resource, and biofertilizer-supporting crop within vegetable, medicinal, and perennial horticultural systems. Due to its high capacity for biological nitrogen fixation, alfalfa can supply substantial amounts of plant-available nitrogen, reducing dependency on synthetic fertilizers and supporting environmentally sound nutrient management. When used as green manure, cover crop, intercrop, mulch source, compost feedstock, or processed organic fertilizer, alfalfa enhances the soil organic carbon (SOC), improves soil structure, and increases the water-holding capacity properties particularly critical in intensive horticultural production. Higher SOC levels also contribute to the improved tolerance of horticultural crops to drought and heat stress through enhanced soil moisture retention and rhizosphere buffering. Alfalfa-based organic inputs stimulate rhizosphere microbial biomass, enzymatic activity, and functional genes associated with nitrogen cycling, strengthening plant–microbe interactions that underpin biofertilizer effectiveness. Evidence from vegetable and perennial systems indicates that alfalfa-derived amendments and rotations increase soil nitrogen availability, support yield stability, and improve soil health over the long-term. In orchards and vineyards, alfalfa cover cropping contributes to carbon sequestration, erosion control, and enhanced soil biological functioning. Overall, alfalfa emerges as a strategic species for integrating organic fertilization and biofertilizer-based approaches into modern horticultural systems, supporting reduced mineral fertilizer inputs while sustaining productivity, soil health, and environmental quality. Full article

Mediterranean regions are forecasted to be increasingly threatened by climate change, leading to the occurrence of extreme events. One strategy to improve the resilience of agricultural systems is to introduce rotations that combine legumes and crops with high intraspecific diversity such as evolutionary populations (EPs). These cropping systems may be characterized by lower external input needs and higher buffering capacity than traditional ones. Our objective was to test if the introduction of wheat EPs impacts soil microbial functions—including microbial biomass, community structure, and enzymatic activity—and soil organic matter composition within a crop rotation framework. We conducted a two-year field experiment at two sites in Italy comparing a modern bread wheat variety to two EPs, evolved in different areas, in rotation with legumes. The composition and processes of rhizosphere microbial communities were characterized using EL-FAME and enzyme activities. In addition, rhizosphere soil organic matter signatures were measured by mid-infrared spectroscopy, and their relationships with microbial parameters were investigated using principal component analyses. The results showed that the EP–rhizosphere relationship, as well as its influence on microbial abundance and activity, is dependent both on the site of origin and local pedoclimatic conditions, although no consistent response was observed across the two sites. These effects may be buffered by the choice of the preceding crop in rotation. Full article

The karst region of Southwest China represents a typical high geological background area characterized by extensive carbonate bedrock and secondary enrichment of heavy metals, particularly cadmium (Cd), in residual soils. Under natural carbonate-buffered conditions, Cd is largely immobilized through mineral associations and surface complexation, resulting in elevated total concentrations but low bioavailability. However, intensified anthropogenic pressures–including acid deposition, mining, excessive fertilization, and improper irrigation—have accelerated soil acidification in paddy fields. Acidification disrupts carbonate geochemical equilibria, weakens buffering capacity, and drives Cd speciation shifts toward more labile forms, thereby enhancing plant uptake and accumulation. These effects are especially pronounced in paddy fields and other systems subject to hydrological and redox fluctuations that further increase Cd mobility. To evaluate these coupled geogenic and anthropogenic controls, we conducted a structured literature synthesis (2016–2026) focusing on peer-reviewed studies of Cd dynamics in Southwestern China’s karst agroecosystems. We critically examine (i) the formation mechanisms and spatial heterogeneity of high-background Cd, (ii) acidification-driven speciation transformation and soil–crop transfer pathways, and (iii) in situ remediation and precision risk assessment strategies. By integrating geological inheritance, geochemical activation, and ecological risk perspectives, this review proposes a conceptual framework to support soil quality standard refinement and adaptive risk management in high-background karst regions. Full article

River ecological restoration in lowland plain basins is often constrained by fragmented river networks, degraded riparian zones, eutrophication risk, and intensive human disturbance. Conventional monitoring approaches rarely connect watershed-scale dynamics with responses from typical restoration units, limiting quantitative evaluation and the separation of direct project outcomes from broader environmental variability. To address this gap, this study developed a collaborative satellite–unmanned aerial vehicle (UAV)–unmanned surface vehicle (USV) monitoring framework and applied it to the Nihe River Basin, China, a lowland plain river undergoing systematic restoration under the Shan-shui Initiative. The framework combines Sentinel-2 time-series imagery, high-resolution Gaofen-1, Gaofen-2, and Jilin-1 imagery, UAV orthophotos, USV observations, and auxiliary environmental datasets. Unlike single-scale monitoring approaches, it links watershed-scale indicators, including water-body dynamics, chlorophyll-related eutrophication risk, riparian ecological background, and soil-water conservation capacity, with unit-scale diagnosis of riparian buffer and riverine wetland restoration. Results showed that river water-body area increased from 37.78 km² to 40.59 km² during 2021–2024, while normalized difference chlorophyll index (NDCI)-based eutrophication risk improved in 9.12% of the monitored river area and degraded in only 0.47%. Riparian vegetation cover remained high, whereas regional soil-water conservation capacity declined due to climatic factors, revealing asynchronous responses between local recovery and regional background conditions. At the unit scale, riparian buffer restoration enhanced buffer continuity and near-bank water quality, as reflected by decreased chemical oxygen demand (COD), increased dissolved oxygen (DO), and limited ammonia nitrogen (NH₃-N) improvement. Riverine wetland restoration promoted land-use adjustment and ecological spatial reorganization. This cross-scale evidence chain supports adaptive management of inland river and wetland restoration projects. Full article

Soil surface moisture (SSM) is a critical indicator of agricultural drought, yet high-resolution projections under climate change remain scarce. This study develops a machine learning framework to predict and project SSM at 1 km resolution across five European Living Labs (LLs), encompassing vineyards, olive groves, and fruit tree systems. Historical Sentinel-1 SSM observations (2014–2024) were used to train ensemble models (Random Forest, XGBoost, ExtraTrees, LightGBM) incorporating climate variables, soil texture, topography, and land use. Tree-based models achieved R² values of 0.63–0.87. Vineyards showed the highest predictability (R² ≈ 0.87), reflecting their sensitivity to short-term atmospheric demand and surface water availability, whereas olive groves were the least predictable (R² ≈ 0.63–0.68), consistent with deeper rooting systems and greater drought buffering capacity. When forced with bias-corrected CMIP6 projections under SSP1-2.6 and SSP5-8.5 for 2041–2070, models indicate minimal changes under SSP1-2.6 but pronounced SSM declines of 8–24% under SSP5-8.5, with historically wetter regions experiencing the largest absolute losses. SHAP analysis confirmed precipitation and potential evapotranspiration as dominant predictors across all crops. This framework provides spatially explicit, crop-relevant SSM projections to support climate adaptation in European agricultural landscapes. Full article

Inland water management is increasingly important under climate change due to the need for landscape-scale water retention, but in situ studies are limited by fluctuating, shallow, and intermittent water cover. This study simulated prolonged waterlogging under controlled laboratory conditions. Four agricultural soils (Calcisol, Arenosol, Chernozem, and Solonetz) were flooded for 40 days using identical 1:5 soil-to-water ratios at two temperature regimes, at 4 and 22 °C. Given that periodic water cover may conflict with agricultural production, particular attention was paid to crop-relevant indicators, including pH, water-soluble salts, and N, P, K. The laboratory simulation revealed significant differences among soil types and between temperature treatments. Elevated Mg concentrations limited the irrigation suitability of leachate derived from Calcisol, with Mg% values ranging from 57 to 64%, exceeding the 50% guideline threshold. Soil buffering capacity controlled phosphorus and potassium dynamics, resulting in stable or slightly increasing AL-soluble nutrient levels, except in low-buffering sandy soils where up to 3–4-fold variability was observed. Reductive conditions developed early in the Calcisol samples, supported by dissolved oxygen saturation values below 20% during the first days of the experiment. Oxygen saturation increased later, only exceeding 60% twice in the cooled Calcisol treatment, while nitrate–ammonium dynamics reflected changing redox conditions. Temperature significantly affected solubility and nutrient mobility, partly through its influence on microbial activity. These findings improve our understanding of inland water–soil interactions and support the development of sustainable, water-retentive land management strategies. Full article

Environmental changes driven by land use and climate variability profoundly affect basin water balance, yet their separate and combined effects remain poorly understood in data-scarce regions. This study investigates the individual and combined impacts of land use/land cover (LULC) and climate change on seasonal runoff in the Rokel-Seli River Basin (RSRB), Sierra Leone, over two periods (1965–1990 and 1991–2016). Using LULC maps derived from 1988 and 2013 Landsat imagery and the Soil and Water Assessment Tool (SWAT), we simulated hydrological responses under four scenario frameworks. The results reveal a marked expansion of urban, bare, and agricultural land at the expense of forest cover. The SWAT model satisfactorily captured streamflow dynamics during calibration and validation. Land use change alone increased wet-season runoff by 6.55% and decreased dry-season runoff by −13.15%, whereas climate change contributed changes of +24.87% and −31.43%, respectively. A double mass curve analysis and Budyko framework further revealed a regime shift toward higher runoff efficiency (runoff coefficient increased from 0.67 to 0.69), indicating a loss of basin retention capacity. Notably, land use change partially masked the full hydrological deficit induced by climate change, acting as a counter-buffering mechanism. This study provides critical evidence for water resource authorities and local stakeholders to develop adaptive land use and water conservation strategies in data-scarce tropical basins, emphasizing the need to consider both climatic and anthropogenic drivers in seasonal water availability assessments. Full article

Saline water irrigation has emerged as a promising approach to mitigate agricultural water shortages; however, its improper use may induce secondary soil salinization. In this study, saline-alkali soil collected from Hami, Xinjiang, was used to conduct a series of indoor one-dimensional vertical soil column experiments. The aim was to systematically investigate the effects of sodium humate and desulfurization gypsum on soil infiltration behavior and the distribution patterns of key cations and anions under different levels of irrigation water salinity. The results showed that sodium humate application markedly improved soil infiltration capacity, while the duration of infiltration decreased with increasing salinity. Under salinity levels of 12 and 16 g/L, the 4 g/kg sodium humate treatment exhibited the most rapid advancement of the wetting front. In contrast, desulfurization gypsum reduced infiltration rates, with the lowest infiltration observed under the 12.5 g/kg treatment at 16 g/L salinity. Under different treatments, the adjusted coefficients of determination (adjusted R²) for the Philip, Kostiakov, and Horton models ranged from 0.8450 to 0.9841, 0.9901 to 0.9989, and 0.9748 to 0.9942, respectively, while the global performance indicator (GPI) ranged from 1.619 × 10⁻³ to 5.103 × 10⁻¹, 4.998 × 10⁻⁹ to 2.166 × 10⁻⁵, and 1.505 × 10⁻⁶ to 2.438 × 10⁻⁴, respectively. These results indicate that the Kostiakov model outperformed the other models in terms of fitting accuracy and overall performance for describing the soil infiltration process. In addition, sodium humate generally increased the sorptivity parameter S in the Philip model and the empirical coefficient K in the Kostiakov model, whereas desulfurization gypsum showed the opposite trend. In terms of salt regulation, sodium humate demonstrated optimal desalination performance at application rates of 6–8 g/kg under low salinity and 4–6 g/kg under high salinity conditions. Conversely, excessive gypsum application tended to exacerbate salt accumulation, although a moderate dosage (5 g/kg) effectively limited the downward migration and accumulation of Na⁺ and Cl⁻. These two ions were identified as the dominant contributors to soil salinization, showing strong positive correlations with soil salt content (SSC), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP). In contrast, Ca²⁺, Mg²⁺, and HCO₃⁻ played beneficial roles in alleviating sodicity through ion exchange and buffering mechanisms. Overall, sodium humate enhanced infiltration and facilitated salt leaching in the upper soil layers under saline irrigation conditions. Although desulfurization gypsum reduced infiltration and increased overall salt content, it contributed to mitigating Na⁺ accumulation in deeper soil profiles. These findings highlight the critical importance of selecting appropriate soil amendments and optimizing their application rates to improve saline water use efficiency and promote sustainable management of saline-alkali soils. Full article

A two-year field experiment was conducted in Tengchong, Yunnan, to evaluate the effects of tobacco monoculture (TM) and maize relay intercropping with tobacco (TIM) on subsequent tobacco growth and the rhizosphere microenvironment. Results showed that TIM significantly increased plant height by 11.8% and maximum leaf length by 12.4% at the vigorous growth stage without reducing yield. Although leaf chloride content increased and the potassium-to-chloride ratio decreased, both remained within high-quality ranges. Relay-cropped silage maize yielded 4.86 t·hm⁻², adding 1.70 × 10⁴ CNY·hm⁻². TIM reduced nitrogen accumulation in aboveground tobacco and temporarily lowered soil organic matter and available potassium, while increasing acid phosphatase, peroxidase, and urease activities. Soil bacterial α-diversity increased, with enrichment of beneficial genera, including Candidatus Solibacter, Talaromyces, and Penicillium. Metabolomics identified 1043 metabolites, with upregulation of galactinol, N-acetyl-L-tryptophan, and 3-dehydroshikimic acid, enriched in cyanogenic amino acid and cysteine–methionine pathways. PLS-PM and Mantel analyses indicated that relay-cropped maize indirectly regulates nutrient availability via microbial and metabolic pathways. These results show that maize relay intercropping creates a soil “legacy effect,” shifting the system from direct nutrient competition to microbially mediated nutrient buffering. Full article

Copper (Cu) is an essential micronutrient, but poorly controlled inputs may increase phytotoxicity risks and alter soil–plant nutrient dynamics. Therefore, Cu formulations that regulate rhizosphere Cu availability are of agronomic interest. This study compared non-encapsulated Cu nanoparticles (CuNPs) and alginate-encapsulated Cu nanoparticles (eCuNPs) in a 42-day pot experiment with Lactuca sativa L. grown in two agricultural soils with different properties, applying 0, 10, 25, 50, and 100 mg of Cu kg⁻¹. Soil properties, Rhizzo-extractable Cu as a proxy of available Cu, plant biomass, Cu accumulation, and nutrient concentrations were evaluated. Rhizzo-extractable Cu increased with dose under CuNPs, particularly in the soil with lower organic matter and ECEC, whereas eCuNPs maintained values closer to the control levels. In the soil with higher organic matter and ECEC, CuNPs were associated with reduced shoot and root biomass at higher doses, while eCuNPs showed a more variable response and, in some cases, higher biomass values. In contrast, biomass remained low across all treatments in the more limiting soil. Cu accumulated mainly in roots, and foliar Cu (FW) remained low and close to typical values reported for lettuce in the USDA FoodData Central database. Alginate encapsulation may reduce short-term Cu mobilization in the rhizosphere and could represent a promising strategy to improve the safety of CuNP applications, particularly in soils with higher organic matter and ECEC. Full article

Dryland farming systems in South Dakota face rainfall variability and rising water demand, which can reduce crop productivity and threaten long-term soil health. We combined field experiments across three dryland sites in South Dakota (Roscoe, Selby, Fort Pierre) with continuous soil moisture monitoring (0–15, 15–30, 30–45 cm) and HYDRUS-1D modeling to evaluate cover crops and soil amendments (biochar, manure) on water retention. During the active cover crop growth period, plots with cover crops consistently exhibited lower soil water content than plots without cover crops, likely due to increased transpiration. Plots with no cover crop (NCC) retained more water than cover crop (CC) plots (Roscoe: 26.27% vs. 24.16% at 0–15 cm). During the primary crop growing season, biochar consistently increased soil moisture (θ) compared with manure and unamended plots. Following a 43-day dry spell (1 July–13 August 2024), soil moisture declined by approximately 0.096 m³ m⁻³ in the biochar plots, compared with 0.125 m³ m⁻³ under manure and 0.216 m³ m⁻³ in the unamended control, exhibiting differences in water retention capacity among treatments. HYDRUS inverse modeling reproduced observed soil moisture dynamics (R² ~ 0.91) and demonstrated higher water content under biochar. Scenario analysis using representative wet (2008) and dry (2012) years showed the cover crop + biochar combination maintained the highest average water content. Results support integrating biochar with cover cropping to buffer drought and improve soil water availability in dryland farming. Full article

The persistence of cadmium (Cd) immobilization in acidic paddy soils is exacerbated by acidification and fluctuating redox conditions that promote Cd re-mobilization. While biochar is a promising amendment, its long-term efficacy in Cd immobilization relative to conventional lime and the underlying mechanisms remain incompletely resolved. This study tested the hypothesis that biochar’s superior effect lies in its durable enhancement of soil pH buffering capacity (pHBC), not merely in increasing initial pH. Using six acidic paddy soils amended with three biochars (corn straw, peanut straw, and seeded sunflower plate) and pH-matched lime [Ca(OH)₂] controls, we quantified pHBC changes, resistance to simulated acidification, and Cd dynamics during a flooding-drying cycle. Results showed that biochar amendments increased pHBC by 24.7–110%, significantly more than lime. Under acid stress, biochar-treated soils maintained higher pH and released 40–85% less soluble and extractable Cd than lime controls at equivalent pH range. Correlation and regression analyses established that the biochar-induced change in pHBC (ΔpHBC) was the strongest predictor of reduced Cd availability, exerting twice the influence of native soil pHBC. During the redox cycle, enhanced pHBC directly attenuated soil re-acidification upon drainage, minimizing Cd re-mobilization. Thus, the durable enhancement of soil pHBC is the central mechanism for biochar’s sustained Cd immobilization, advocating a strategic shift from transient pH adjustment to building inherent soil buffering resilience for long-term remediation security. Full article

Optimizing planting density is a critical, cost-effective strategy for sustainable agricultural intensification, yet moving beyond static recommendations to environment-specific precision management remains a key challenge. This study establishes a three-step framework (comprising zoning, response extraction, and machine learning modeling) to determine optimum planting density (OPD) for rice (Oryza sativa L.). Utilizing a data-driven synthesis of 960 field observations from the Northeast Black Soil Region (NBSR) of China, we identified distinct spatial variability in OPD (16.6 to 37.4 × 10⁴ hills ha⁻¹). Northern regions computationally prioritized higher densities, aligning with agronomic strategies to offset thermal constraints, while southern regions favored lower densities to reduce canopy competition. Soil properties, particularly Soil Organic Carbon (SOC), pH, Cation Exchange Capacity (CEC), and Total Nitrogen (TN), were identified as the dominant predictive indicators, collectively surpassing climatic factors in their predictive importance. This highlights the foundational role of soil buffering capacity in estimating crop tolerance to density management. Based on model-derived estimates, optimized density management indicated potential yield improvements of 3.8% to 9.7% (up to 872.32 kg ha⁻¹) compared to conventional practices. By replacing uniform practices with dynamic, environment-driven strategies, this work contributes to Sustainable Development Goals (SDGs) 2 (Zero Hunger), 12 (Responsible Consumption and Production), and 13 (Climate Action), offering a scalable solution for diverse rice production systems under climate change. Full article