Search Results (3,021)

In modern livestock production, a reliable supply of high-quality forage is essential for sustaining animal productivity and product quality. Although nitrogen (N) fertilization can promote forage growth, excessive N inputs often result in low agronomic nitrogen use efficiency (NAUE) and increased environmental risks. Biochar, owing to its porous structure, high specific surface area, and physicochemical stability, can improve soil physical properties, enhance water and nutrient retention, and regulate soil N availability. However, the mechanisms by which biochar combined with reduced N rate fertilization affects NAUE in artificial grasslands remain insufficiently quantified. A two-year field experiment was conducted at the Grassland Science Experimental Station of Xinjiang Agricultural University on the northern slope of the Tianshan Mountains, Xinjiang, China. Eight treatments were established using a factorial design with two biochar rates (0 and 20 t·ha⁻¹; B0 and B20) and four N application rates (0, 75, 150, and 225 kg·ha⁻¹; N0, N75, N150, and N225). Results showed that biochar application significantly decreased soil bulk density and increased soil water content and electrical conductivity. It also elevated soil total carbon, total nitrogen, total phosphorus, NH₄⁺–N, and NO₃⁻–N concentrations, with B20N150 exhibiting the highest overall nutrient status. Plant community diversity indices did not differ significantly among treatments (p > 0.05), though B20 slightly enhanced Shannon–Wiener and Simpson indices under N0 and N75. Moderate N application significantly increased hay yield, whereas the highest N rate (225 kg·ha⁻¹) did not further improve yield and reduced NAUE. Biochar combined with N75 or N150 improved NAUE, and B20N150 achieved the best balance of high hay yield and high NAUE. Structural equation modeling revealed that soil water content (path coefficient = 0.45), NH₄⁺–N (0.27), and plant community diversity (0.20) were key positive drivers of NAUE, with biochar exerting indirect effects primarily via improving soil water and available N. Collectively, applying 20 t·ha⁻¹ biochar with 150 kg·ha⁻¹ N (B20N150) is recommended as an optimal strategy for N rate reduction and NAUE enhancement in artificial grasslands of arid and semiarid regions. Full article

Accurate monitoring of inundation in rice paddies is essential for optimizing water use efficiency and mitigating methane emissions; yet, detecting water beneath dense rice canopies remains a major challenge. This study proposed a reliable classification approach applied to the Winter–Spring 2025 season in An Giang province, Vietnam, by integrating multi-temporal ALOS-2 PALSAR-2 (L-band) and Sentinel-1 (C-band) SAR data with in situ field surveys. Time-series Sentinel-1 observations were used to estimate rice phenology (rice age), while multi-polarization backscatter from ALOS-2 PALSAR-2 was analyzed to discriminate inundated from non-inundated conditions across different growth stages. Results demonstrated that L-band signals, particularly in VV polarization, penetrated dense vegetation effectively, enabling classification of inundated vs. non-inundated fields with an overall accuracy of 81% and a Kappa coefficient of 0.77. The resulting multi-date inundation maps revealed distinct flooding regimes consistent with local field survey observations. These findings demonstrated the potential of L-band VV SAR data for characterizing sub-canopy inundation conditions under rice canopies. Crucially, the approach provides essential data for greenhouse gas inventories and supports the verification of low-emission water management practices, such as Alternate Wetting and Drying (AWD). Overall, the study demonstrated the value of multi-frequency SAR integration for advancing agricultural monitoring and climate-smart management in rice-growing regions. Full article

Sustainable agricultural development requires regional agricultural systems to balance output growth, resource efficiency, ecological protection, and long-term resilience. In mountainous and ecologically sensitive regions, identifying the development constraints and statistically derived marginal contribution thresholds of agriculture is essential for promoting green transformation and sustainable land use. Taking Yunnan Province, China, as a representative plateau mountainous agricultural region, this study uses provincial annual data from 1990 to 2023 to quantitatively identify the key drivers and threshold characteristics of agricultural development under multidimensional constraints. A multidimensional indicator system was constructed covering fiscal and investment support, agricultural production inputs, rural infrastructure, and labor and population conditions. Ridge regression was employed to address multicollinearity among explanatory variables, Bootstrap approximate inference was used to improve the robustness of coefficient estimation, and the SHAP interpretation framework was introduced to rank key driving factors and identify marginal contribution thresholds. By integrating ridge regression, Bootstrap approximate inference, SHAP-based contribution ranking, and threshold identification, the proposed framework advances prior agricultural sustainability studies by linking coefficient-based factor analysis with interpretable marginal contribution thresholds under conditions of high multicollinearity and multidimensional resource constraints. The results show that agricultural development in Yunnan is characterized by multidimensional resource and infrastructure constraints. Rural electricity consumption, total reservoir storage capacity, fixed asset investment in agriculture, forestry, animal husbandry and fisheries, local public fiscal budget expenditure, and agricultural population generally act as positive supporting factors. Rural electricity consumption is the most stable and core driver across the aggregate and three sectoral models. In contrast, pesticide and fertilizer inputs show significant negative associations in most models, suggesting that future agricultural development in Yunnan is unlikely to be sustainably supported by continued expansion of high-intensity chemical inputs. Sectoral heterogeneity is also evident: agriculture and animal husbandry are more dependent on energy, water resources, and mechanization, whereas forestry shows a more distinct operational structure. The SHAP dependence analysis identifies several statistically derived marginal contribution thresholds, including rural electricity consumption of approximately 6.055 billion kWh, total reservoir storage capacity of approximately 10.395 billion m³, total agricultural machinery power of approximately 19.8324 million kW, pesticide use of approximately 37,500 tons, and fertilizer application of approximately 1.5238 million tons. These values should be interpreted as empirical transition points in the modeled marginal contributions rather than definitive biophysical ecological limits. They indicate that the sustainability-related constraint structure of agricultural development in Yunnan is not a single output ceiling but a composite interval shaped by infrastructure support capacity, factor allocation conditions, and the declining marginal contribution of high-intensity chemical inputs. The findings provide directional quantitative evidence for sustainable agricultural governance, agricultural green transformation, and differentiated policy discussion in mountainous agricultural regions and offer reference implications for advancing SDG 2 and SDG 15 through the coordination of food-related production, resource use efficiency, and ecosystem conservation. The identified thresholds should be interpreted as model-derived marginal contribution transition points rather than operational policy cutoffs or directly enforceable ecological standards. Full article

Understanding evapotranspiration (ET) partitioning into soil evaporation (E) and plant transpiration (T) is crucial for improving agricultural water use efficiency in water-scarce regions. The isotope mass balance (IMB) method and AquaCrop model are two widely used approaches for ET partitioning, yet their comparative performance across different crop growth stages remains poorly characterized. This study systematically compared these two methods using two consecutive years (2012–2013) of field isotopic observations in a summer maize field on the North China Plain, a core maize production area facing severe agricultural water scarcity. Stable isotope analysis showed that the local meteoric water line (LMWL) had a slope lower than the global meteoric water line. The 0–5 cm surface soil water evaporation lines had slopes of 5.84 (2012) and 8.06 (2013), confirming significant evaporative enrichment in the topsoil. Plant water isotopic composition closely resembled that of 40–100 cm deep soil water, indicating limited root uptake from the surface layer. IMB-estimated transpiration ratio (T/ET) exhibited distinct phenological patterns, increasing from 37 to 44% at jointing to a peak of 94–96% at filling, then declining to 84–85% at maturity. The two methods agreed well during filling to maturity (differences of 2–10%), but compared with the IMB method, AquaCrop substantially underestimated T/ET at jointing (0.9% vs. 43.8% in 2013) due to its canopy-cover-based transpiration algorithm. These findings identify the filling stage as the critical water demand period, providing a quantitative reference for precision irrigation management under similar climate and soil conditions. Full article

Hydrothermal carbonization (HTC) is a promising thermochemical process for valorizing wet biomass and organic waste streams, generating hydrochar, gas, and a liquid phase commonly referred to as HTC process liquid or the aqueous phase. Depending on feedstock type and process severity, hydrochar typically accounts for approximately 40–70 wt.% of the initial dry feedstock, the liquid phase for about 30–60 wt.% in lignocellulosic and agricultural residues, and the gas phase for about 1–10 wt.%, while highly hydrated waste streams may generate even higher liquid-phase shares. Although hydrochar has traditionally been considered the main energy product, the liquid phase may retain approximately 20–65% of the initial feedstock carbon and around 15–25% of the initial energy content. However, its high chemical oxygen demand, elevated organic carbon content, variable biodegradability, toxicity, and inhibitory compounds often lead to its classification as a wastewater stream requiring treatment. The crucial novelty of this review is its system-oriented evaluation of HTC process liquid as an energy-bearing and system-integrating stream rather than merely as a wastewater by-product or as a substrate for isolated valorization routes. Therefore, this review evaluates the role of HTC process liquid in energy systems, focusing on its formation mechanisms, chemical composition, energy potential, valorization pathways, integration strategies, and environmental implications. The reviewed evidence shows that HTC process liquid contains a complex mixture of dissolved organic compounds, including volatile fatty acids, sugars, furans, phenols, ketones, aldehydes, amino acids, ammonia, and nitrogen-containing heterocycles. These compounds may support anaerobic digestion, dark fermentation, aqueous phase reforming, electrochemical conversion, nutrient recovery, and process-water recirculation. Among these routes, anaerobic digestion is currently the most mature, although its efficiency depends strongly on HTC severity, feedstock type, inhibitor formation, and microbial adaptation. Hydrogen-oriented and electrochemical pathways offer additional opportunities but still require further validation using real HTC liquids, standardized yield reporting, and long-term stability assessment. Overall, HTC process liquid should not be regarded solely as an environmental burden, but as a chemically complex and energy-rich stream that may improve the performance of integrated HTC-based bioenergy systems. Future research should focus on standardized liquid-phase energy metrics, long-term process integration, toxicity control, and experimentally validated techno-economic and life-cycle assessments. Full article

Agricultural and food-processing residues, as well as fruit by-products, represent widely available but still underutilised resources. Although numerous laboratory-scale studies have demonstrated their ability to remove heavy metals from contaminated water, their practical implementation remains limited by incomplete understanding of long-term stability, regeneration efficiency, and end-of-life environmental safety. This review critically evaluates the current state of biosorbent research, with particular emphasis on the full life cycle of these materials, including adsorption performance, regeneration strategies, repeated-use potential, and post-exhaustion management. While focusing primarily on agricultural residues, the review also integrates key findings from alternative materials such as algae, microbial biomass, and industrial sludge to provide a comprehensive evaluation. Particular attention is given to the distinction between desorption and regeneration, metal recovery from desorption streams, and the associated environmental burden of secondary waste generation. In addition to commonly proposed valorisation routes, such as incorporation into construction materials, thermal conversion, and reuse in energy or catalytic applications, the review highlights that most end-of-life pathways remain partial solutions rather than true closed-loop systems. In many cases, only a small fraction of spent biosorbents can be effectively incorporated into secondary products, while remaining residues still require further treatment or disposal. The lack of standardised criteria for defining biosorbent exhaustion and performance thresholds further limits comparability across studies and hinders scale-up. Overall, current evidence suggests that biosorbent-based wastewater treatment should be considered a promising but still partially circular system, where full material closure has not yet been achieved. Addressing these gaps is essential for advancing toward more robust and environmentally sustainable implementation and for improving the circularity of biosorbent-based wastewater treatment systems. Full article

Rice, a staple food for over half of the global population, faces significant threats from environmental stressors such as heavy metal (HMs) contamination, notably cadmium (Cd) and arsenic (As), and increasing drought severity, exacerbated by climate change. These challenges not only compromise rice yield and quality but also pose serious food safety risks due to HM accumulation in grains, endangering human health. Modified biochar (MBC), a carbon-rich material derived from the pyrolysis of organic matter with post-treatment enhancements, has emerged as a strategy to address these dual stressors. MBC application (typically 5–20 t ha⁻¹) reduces Cd and As bioavailability in paddy soils by 40–60% and decreases metal accumulation in rice grains by 20–85% compared to the control. Under drought conditions, MBC improves soil water-holding capacity by 11–45% and enhances crop water use efficiency by 15–24%, leading to yield improvements of 20–50% under moderate water deficit. Furthermore, MBC supports nutrient availability, fosters robust root systems, and enhances soil aeration, collectively improving rice growth under adverse conditions. Beyond its agronomic benefits, MBC provides a framework for addressing multiple challenges by integrating scientific innovation, policy alignment, and community participation. This approach not only reduces heavy metal toxicity and strengthens plant resilience but also enhances food security and advances Sustainable Development Goals (SDGs 2, 3, 4, 12, 13, 15, 17). By promoting environmentally sustainable agriculture and contributing to climate change mitigation, MBC represents a transformative tool for ensuring sustainable rice production in the face of global challenges. Full article

The paper analyses the key challenges and threats to contemporary food security, highlighting the interconnections between large-scale agricultural production and environmental degradation. Selected issues are only a part of this complex phenomenon. The main aim is to initiate a discussion and identify the risks and challenges currently facing agriculture in the context of ensuring food security, and to highlight the potential consequences of treating current agricultural land management practices as a chance for food security. The paper discusses, among other things, the relationship between high-production efficiency and system resilience, and the evolution of the policy framework within the Common Agricultural Policy, which reflects the challenges facing the agricultural sector. A key theme concerns the currently dominant model of agriculture. Particular attention is paid to its negative effects, such as high water consumption, the widespread use of monocultures, the loss of biodiversity, and the excessive use of chemicals and antibiotics. The analysis is further complemented by a discussion of challenges related to safeguarding food security. Overall, the paper underlines the necessity of transforming ways of thinking about food security in the long-term perspective (now and for the future generation) in order to protect natural resources and public health, as well as for reorienting agricultural subsidies towards the support of environmentally sustainable practices. Such a perspective on complex phenomena like food security is essential for maintaining it in the context of escalating crises, including climate change and other global and local challenges. Full article

The adoption of sustainable agricultural practices is essential to cope with climate change and to ensure soil health, efficient nutrient use, and food security. This study aims to delve into the effects of the use of different mulching techniques, both traditional and with an innovative ecological and sustainable mulch called hydromulch, on soil quality parameters, gas-exchange parameters and the final quality of the artichoke fruit (Cynara cardunculus subsp. scolymus L. (Heigi) cv. Symphony), as well as its impact on the metabolomics profile. The experimental design consisted of three blocks, each with three treatments: traditional polyethylene (PE) mulch, a rice husk-based hydromulch, and a bare soil control. The results show an increase in the physical quality of the artichokes grown with both mulches, as well as a direct impact on the primary and secondary metabolism, being more pronounced in the artichokes grown with hydromulch. In particular, hydromulch significantly up-regulated metabolites associated with the melatonin, serotonin, and polyamine pathways, suggesting a marked metabolic response compared with both polyethylene mulch and bare soil treatments. Furthermore, soil organic carbon (SOC) and soil organic matter (SOM) were increased in hydromulched soils. Gas exchange measurements revealed that hydromulched plants reduced stomatal conductance and transpiration, resulting in enhanced intrinsic water use efficiency. These improvements contribute to the production of high-quality, nutritionally enriched crops with direct relevance to food safety and sustainable agri-food systems. Full article

Soil water availability, salinity dynamics, and nitrate transport are key factors controlling agricultural sustainability in arid environments characterized by limited water resources and high evaporative demand. This study evaluated the combined effects of soil texture, nitrate–nitrogen application, and sawdust mulching on soil water retention, evaporation losses, salinity redistribution, and nitrate movement in loamy sand and sandy clay loam soils under controlled greenhouse conditions. Results showed that soil texture was the dominant control on hydrochemical behavior, with sandy clay loam exhibiting higher water retention and lower drainage than loamy sand. Sawdust mulching significantly improved soil water conservation by reducing evaporation and stabilizing moisture distribution, while the 4 cm mulch treatment achieved the highest overall CSI performance. Evaporation strongly governed salinity accumulation in surface layers, whereas mulching reduced salt build-up and promoted a more uniform salinity profile. Nitrate transport closely followed water fluxes, resulting in higher leaching in loamy sand and greater retention in sandy clay loam. Increasing nitrogen application enhanced nitrate mobility and leaching in both soils. A Composite Sustainability Index (CSI) was developed to integrate soil water conservation, evaporation reduction, salinity control, and nitrate retention into a unified metric. Sensitivity analysis demonstrated that treatment rankings were largely unaffected by alternative weighting schemes, confirming the robustness of the CSI framework. The CSI identified mulch application, particularly the 4 cm mulch treatment, as the most effective management option based on overall sustainability performance. The CSI framework provides an integrated decision-support tool for evaluating coupled water–salt–nitrate interactions and improving water use efficiency and salinity management in arid agricultural systems. This study offers a novel integrated CSI-based framework for simultaneously quantifying hydrological and hydrochemical soil responses under mulch management in arid environments. Full article

Modern agriculture in developing regions faces significant challenges due to labor scarcity and the health hazards associated with the manual application of chemical treatments. This study presents the design, development, and techno-economic evaluation of an experimental hexacopter unmanned ariel vehicle (UAV) platform specifically tailored for crop protection on fragmented, smallholder farmlands. The research aims to bridge the gap between expensive imported technology and the practical needs of small-scale farmers by providing a cost-effective, locally manufacturable solution. The methodology involved the integration of a modular spraying system and optimized control architecture into a high-stability hexacopter frame. Experimental evaluations focused on flight stability, payload capacity, and spray uniformity using water-sensitive media. The results indicate that the developed platform achieves high coverage efficiency while significantly reducing chemical waste compared to traditional manual methods. Furthermore, the economic analysis suggests that the operational costs are substantially lower than those of comparable imported systems, offering a favorable payback period within a few crop seasons. These findings demonstrate that an indigenous UAV spraying platform can enhance both operational safety and economic feasibility for smallholder agriculture. Full article

Agricultural reconversion has become a key strategy for the continuity and competitiveness of primary-sector productive units, confronting scenarios such as low profitability, environmental pressures, and changes in agri-food markets. The objective of this study was to identify the economic, social, and environmental factors that influenced the agricultural reconversion to lemon cultivation (Citrus limon) in production units in the municipality of Calvillo, Aguascalientes, Mexico. During 2023 and 2024, a total of 32 semi-structured interviews were conducted with producers who had undertaken restructuring processes, from which perception variables were constructed across three dimensions: economic, social, and crop management. Through cluster analysis, three distinct profiles were identified based on their perceptions, resource use, and organizational characteristics (p < 0.05). Results indicate that economic factors are the main driver of productive change (low crop profitability p = 0.0035); however, environmental dimension and efficient resource management, particularly water, are crucial to consolidating the conversion. Furthermore, government support, production experience, and membership in organizations influence perceptions of viability and the prospects of the new crop. The findings suggest that agricultural production restructuring does not follow a uniform pattern, but is shaped by structural, perceptual, and contextual factors, highlighting the importance of targeted public policies and integrated strategies for technical and organizational support. Full article

The present study investigates the development of non-autoclaved aerated concrete (NAAC) incorporating rice husk ash (RHA)-derived amorphous silica, polypropylene microfibers, and a polycarboxylate-based superplasticizer to improve mechanical performance and durability while maintaining low density and thermal conductivity. Experimental investigations included density, compressive strength, thermal conductivity, water absorption, X-ray diffraction (XRD), microstructural observations, and TG–DTA analysis. The developed compositions containing 5–7% RHA and 0.10–0.20% polypropylene microfibers achieved compressive strength values of 4.5–4.8 MPa at densities of 520–560 kg/m³, which are comparable to or higher than values commonly reported for non-autoclaved aerated concrete of similar density. Thermal conductivity decreased to 0.12–0.13 W/(m·K), while water absorption was reduced to 15–18%. XRD, microstructural, and TG–DTA analyses suggested enhanced hydration reactions and improved development of the cementitious matrix due to pozzolanic interaction between amorphous silica and calcium hydroxide. The incorporation of polypropylene microfibers was associated with improved structural homogeneity of the developed NAAC compositions, whereas the superplasticizer enhanced mixture homogeneity and pore stability. The results suggest that the combined use of agricultural waste-derived silica and fiber reinforcement provides an effective approach for producing sustainable and energy-efficient NAAC without autoclave curing. Full article

Biochar, a carbon-rich material produced through pyrolysis of biomass under limited oxygen conditions, offers a potentially sustainable and cost-competitive solution (qualitative assessment; quantitative LCA and techno-economic data are beyond the scope of this review) for the removal of heavy metals from wastewater. Its high porosity, surface area, and surface functional groups enable diverse adsorption mechanisms, including complexation, ion exchange, and precipitation. Feedstock selection and production parameters critically influence biochar’s physicochemical properties and adsorption performance. Modification techniques such as chemical functionalization, metal impregnation, and composite formation enhance removal efficiency and selectivity for specific contaminants. Applications span industrial, municipal, and agricultural wastewaters, addressing multi-contaminant challenges under variable environmental conditions. Factors affecting removal efficiency include pH, temperature, contaminant concentration, and competing ions, while regeneration methods are essential for maintaining long-term functionality and are discussed. Biochar can be reused and regenerated using bases and acids, but environmental risks related to biochar use, including potential contaminant leaching and ecological impacts, require careful management and regulatory compliance. Future research should focus on novel modification strategies, scaling production for industrial use, and optimizing integration within treatment systems to meet stringent discharge standards and promote sustainable water management. Full article

As the core actuation component of intelligent precision spraying systems, the variable-rate nozzle is essential for achieving on-demand agricultural spraying; improving the use efficiency of water, fertilizers and pesticides; and reducing environmental pollution. This paper systematically reviews the development of agricultural variable-rate nozzles, from early mechanical profiling structures to modern intelligent control technologies based on Pulse Width Modulation (PWM). First, the existing variable-rate nozzles are classified into three major categories: electromagnetic-integrated type, centrifugal type, and variable-diameter type. A comparative analysis is conducted from three dimensions of working principle, performance characteristics and application scenarios, to delineate the respective advantages and limitations of each nozzle category. Second, the paper examines key technological advances in three areas: high-frequency solenoid valves, PWM control, and pressure and flow stabilization. It identifies the nonlinear response of solenoid valves, flow distortion under low duty cycles, and water hammer pressure fluctuation induced by high-speed switching as the three core technical bottlenecks at the current stage. Subsequently, the latest achievements and typical methodologies of variable-rate nozzles in structural design, simulation and experimental analysis are systematically reviewed, and their application performance in scenarios including field crops, orchards, protected agriculture and beyond are summarized. Finally, the remaining open issues in this field are put forward. It is suggested that future research should focus on key breakthroughs in the development of corrosion and wear-resistant high-frequency solenoid valves, the formation mechanism and suppression methods of pressure fluctuation, as well as adaptive algorithms based on machine learning or Model Predictive Control (MPC), to promote the leapfrog development of agricultural variable-rate nozzle technology from single variable control to multi-factor coupling optimization. All references cited in this paper are from articles published after the year 2000. Among them, the literature published in the last decade accounts for 86.6%, and literature published in the last five years accounts for 58.9%. Full article