Search Results (1,083)

Most major crops in agricultural soils exhibit relatively low nutrient use efficiency for nitrogen (N), phosphorus (P), and potassium (K), often necessitating supplemental nutrient inputs to achieve sustainable yields. Furthermore, the increasing use of biowastes such as compost, manure, and biosolids, which frequently have nutrient ratios that do not match crop requirements, has contributed to excessive nutrient inputs and subsequent accumulation in soils. This situation has been further exacerbated by intensive farming practices involving multiple cropping cycles per season. Overuse of nutrients causes them to accumulate in the soil, creating a legacy nutrient pool. The application of biochar as soil amendment is considered a potential strategy to control legacy nutrients dynamics. The current review inspects the possible value of biochar in modulating legacy nutrient reserves in the soil, thereby increasing the bioavailability of nutrients and improving crop yield. This review discusses the search scope and synthesis approaches for the bibliometric methodological component through rigorous screening process (Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)), focusing on journal articles published in last 20 years that specifically address legacy nutrient management. The significance of the economic and environmental effects of legacy nutrients and the insufficient knowledge of how biochar application influences nutrient dynamics in soil highlight the necessity for additional research to address current gaps. Full article

The increasing use of silver nanoparticles (AgNPs) as nanoagrochemicals raises important environmental and toxicological considerations of their usage. AgNPs influence soil microbiome functioning, which regulates essential nutrient availability. However, their effects on key chemical soil health indicators remain unclear, with existing studies limited to concentrations ≥10-fold above predicted environmental levels. The aim of the work was to evaluate the effect of AgNPs at a realistic concentration of 10 μg/kg on the principal chemical soil health indicators, including acidity, redox potential, electrical conductivity, contents of NPK, and soil organic carbon (SOC). In addition, dissolved organic carbon and nitrogen (DOC and DON) and water-extractable elements (Al, Ca, Fe, K, Mg, Na, P, S, and Si) were also examined. The laboratory experiment was carried out for 3 months on Retisol, Chernozem, and Solonetz. AgNPs stabilised with carboxymethylcellulose (AgNP-CMC) or polyvinylpyrrolidone (AgNP-PVP) were used. AgNP-induced changes exhibited non-monotonic patterns, peaking at 2–3 months of incubation. A statistically significant effect observed across all soils following AgNPs application included only increased water-extractable Fe. In addition, AgNPs increased nitrate content 1.1–1.4-fold in Retisol and Chernozem, while available phosphorus increased 1.4-fold in Solonetz. However, changes were transient, indicating no pronounced long-term impact on soil properties. Partial Least Square (PLS) analysis revealed that chemical soil health indicators and water-extractable elements do not reliably discriminate between control soils and soils amended with AgNPs. Although our study shows that AgNPs had neither markedly negative nor positive effects on chemical soil health indicators or water-extractable element contents, future research should prioritise field trials. Model experiments under optimised microbial activity conditions limit direct extrapolation to field scenarios. Full article

Microbial inoculation is widely used to improve composting performance, yet its effectiveness hinges on inoculum composition, substrate characteristics, and composting technology, which remain poorly understood. This study compared single versus mixed inoculants across different substrates and assessed their interactions with biochar amendment and nanomembrane covering, focusing on organic matter transformation, inorganic nutrient dynamics, and biological pollution control. Mixed inoculation significantly improved heating performance in cattle manure compost compared to single strains (p < 0.05) and sustained thermophilic conditions in sludge-sawdust compost, but showed limited impact in chicken manure-sludge compost. It reduced humic acid (HA) accumulation in chicken manure-sludge compost (14.29% to −39.28%) while increasing HA content in sludge-sawdust compost (3.55–5.41 g/kg, p < 0.05). Inorganic nitrogen retention was enhanced; specifically NO₃⁻-N concentrations rose by 175.1–222.6% in the chicken manure-sludge and by 6.7–17.9% in the sludge-sawdust compost. Microbial community analysis indicated enrichment of inoculant strains during the thermophilic phase, supporting nitrogen conservation and humification. However, inoculation increased potential pathogenic bacteria by over 51.2% across all composts and enriched predicted antibiotic resistance genes (ARGs) by 9.9–22.96% in chicken manure-sludge compost, while reducing the membrane covering’s inhibitory effect on predicted ARGs (rebound by 29.5%). Moreover, we found that the predicted ARG profiles, derived from 16S-based PICRUSt2 functional inference, covaried strongly with microbial community structure, with environmental factors such as organic carbon shaping predicted ARG dynamics mainly through indirect effects on microbial communities. These findings highlight that while mixed inoculation boosts composting efficiency, it also raises biosafety concerns. Thus, a comprehensive evaluation integrating organic, inorganic, and biological perspectives is essential before promoting thermophilic inoculants. Full article

Cadmium (Cd) and lead (Pb) co-contamination in construction and demolition waste landfill soils presents a significant challenge to ecosystem health, necessitating effective remediation strategies. This study investigated a synergistic approach combining a composite amendment (compost, superphosphate, desulfurized gypsum) with seven plant species to elucidate the interactions driving metal immobilization and phytoextraction. The amendment significantly altered soil properties: it reduced total Cd while increasing its bioavailability, and enhanced soil fertility (e.g., elevated organic matter and total nitrogen). Plant responses varied: Solanum americanum Mill. and Tagetes patula L. exhibited high Cd phytoextraction capacity, whereas Lolium perenne L. sequestered Cd/Pb primarily in roots. The bacterial community shifted from an oligotrophic, stress-tolerant state (e.g., Sphingomonas-dominated) in contaminated soil to a copiotrophic, functionally active state (e.g., Streptomyces-enriched) in amended soil. Community structure was strongly correlated with available Cd, pH, and nutrient levels. Key microbial biomarkers were specifically enriched in different plant rhizospheres. In contrast, the fungal community exhibited minimal responsiveness. These findings demonstrate that remediation efficiency is governed by an integrated “amendment–plant–microbe” framework: amendments regulate metal bioavailability, plants execute extraction or stabilization, and the restructured microbiome supports nutrient cycling and plant health. This integrated remediation strategy directly supports the Sustainable Development Goals of the 2030 Agenda, especially on environmentally sound management of chemicals and wastes and land degradation neutrality. This mechanistic understanding underscores the necessity of combined biological and chemical strategies for sustainable remediation of co-contaminated soils, ultimately enabling ecological reclamation and safe recycling of such urban marginal lands into productive uses. Full article

Organic amendments can mitigate soil acidification and degradation, yet their long-term effects on soil microbiome, functions, and crop productivity remain underexplored in latosolic red soils. This study aimed to elucidate how different fertilization regimes reshape soil microbial communities and predicted functions, and how these changes link to sweet potato productivity after 15 years. Soil and plant samples were collected from a 15-year field experiment on latosolic red soil under five treatments: no fertilizer (CK), chemical fertilizer alone (NPK), and chemical fertilizer combined with commercial manure (NPK + CM), pig manure (NPK + PM), or rice straw (NPK + RS). Soil properties, bacterial and fungal communities, and predicted functions (FAPROTAX, FUNGuild) were analyzed. The results showed that long-term NPK alone significantly acidified soil (pH decreased by 1.49 units), whereas NPK + PM increased pH by 1.38 units relative to NPK, and also increased soil organic carbon, available nutrients, and sweet potato yield (by 31% compared with NPK). Soil pH was strongly associated with reshaping the microbial community. NPK + PM enriched beneficial phyla (e.g., Myxococcota, Nitrospirota, Latescibacterota, Entotheonellaeota, and Mortierellomycota) and enhanced predicted chemoheterotrophic, predatory or exoparasitic, and saprotrophic functions. Variance partitioning showed that nutrients, key microbial taxa, and predicted functions jointly explained productivity variation (adjusted R² = 0.9386). Thus, chemical fertilizer combined with pig manure is an effective strategy to mitigate soil acidification and improve sweet potato productivity by regulating soil nutrient-microbiome interactions. Our findings support reshaping the microbiome via organic amendments for sustainable agriculture in acidic soils. Full article

Soil acidification and low nutrient availability in acidic red soils are major constraints on pecan (Carya illinoinensis) productivity and fruit quality. However, the integrated effects of quicklime and biochar application in pecan orchards on acidic red soils remain poorly understood. In this context, a field experiment was conducted in an 8-year-old pecan orchard in an acidic red soil region to evaluate the effects of sole and combined applications of biochar and quicklime at different ratios on soil properties, fruit yield, and quality. The results showed that the combined application of biochar and quicklime showed greater benefits for soil fertility, fruit yield, and kernel quality than single-amendment treatments. The combined treatments significantly increased soil pH by 0.47–2.15 units relative to the control and markedly improved soil nutrient status. After 12 months of application, SOM contents under L1B–L3B were 20.8–23.2% higher than those under the corresponding quicklime-only treatments, reaching 37.57–43.37 g·kg⁻¹. The combined treatments also maintained higher total nitrogen, total phosphorus, and available potassium levels than the corresponding quicklime-only treatments, with TN under L1B–L3B reaching 1.65–1.78 g·kg⁻¹, representing a 126.0–166.7% increase over their respective quicklime-only treatments. The combined treatments also generally enhanced soil biological activity and improved fruit yield and quality. Their effects on fruit traits varied with application ratio: the low-dose treatment (L1B, 2 kg biochar + 1 kg quicklime) was more effective in improving physical traits such as dry kernel weight and kernel percentage; the medium-dose treatment (L2B, 2 kg biochar + 1.5 kg quicklime) produced the highest single-tree yield, reaching 26.80 kg·tree⁻¹, which was 24.25% higher than the control and significantly higher than all single-amendment treatments (23.43–25.07 kg·tree⁻¹); and the high-dose treatment (L3B, 2 kg biochar + 2 kg quicklime) was more favorable for improving nutritional quality, increasing amino acid and vitamin E contents to 1267.01 μg·kg⁻¹ and 153.22 μg·g⁻¹, respectively, which were 45.41–91.90% and 5.02–78.77% higher than those under the single-amendment treatments. Overall, the combined application of biochar and quicklime effectively alleviated soil acidification, improved soil fertility, and promoted higher fruit yield and quality, providing a scientific basis for the efficient, high-quality, and sustainable development of pecan orchards in acidic red soil regions. Full article

Vermicomposting is an environmentally sustainable, economically viable, and agronomically valuable method for converting organic waste into nutrient-rich soil amendments, thereby supporting sustainable development. However, the fertilization efficiency of vermicompost can vary significantly depending on the physicochemical properties of the feedstock used. This study aims to compare different feedstocks on vermicompost and evaluate their performance on soil fertility and plant nutritional status. Organic matter (OM), pH, salinity (EC), total Kjeldahl nitrogen (TKN), total phosphorus (TP) and total potassium (TK) of various vermicompost samples were taken into consideration to evaluate their fertilization efficiency as performance determinants in terms of plant growth, plant nutritional status, yield, crop quality and cost with the aim of determining the weights of the specific parameters in the total performance using multi-criteria decision-making (MCDM) methods. The integrated ENTROPY-TOPSIS method was used. Twenty-one different vermicompost feedstock analyses were collected from the literature and compared in order to create an agronomic performance ranking based on the selected criteria. The ENTROPY method revealed that the TP was the most influential factor (21.6%), followed by the EC (20.7%) and the TK (18.5%), while the OM had the lowest impact (11.3%). Based on the TOPSIS ranking, vermicompost from brewer’s spent grain achieved the highest performance, followed by cow manure plus rice straw and olive pruning waste, whereas paper waste ranked at the bottom. A comparative analysis with other objective MCDM weighting methods proved strong correlations, particularly with WENSLO, MPSI and LODECI methods, confirming the robustness of the ENTROPY method. Full article

Cadmium (Cd) accumulation in agricultural soils from prolonged phosphate fertilizer application threatens food safety in Southeast Asia, yet the combined performance of vermicompost (VC), biochar (BC), and Azolla microphylla for Cd immobilization remains poorly characterized. We evaluated their individual and combined effects in a Cd-spiked Korat soil (100 mg kg⁻¹ Cd as Cd(NO₃)₂) under controlled laboratory conditions. A completely randomized pot experiment with eight treatment combinations (four amendment regimes × two Azolla levels, n = 3) was incubated for five weeks; total and exchangeable Cd, selected soil properties, and Eisenia fetida growth were assessed before and after treatment. The combined of soil, cadmium vermicompost and biochar (SCVB) + Azolla treatment reduced total Cd by 41.13% and exchangeable Cd by 81.02%, significantly outperforming single amendments, while raising organic matter to 6.31% and nitrogen (N), phosphorus (P), and potassium (K) availability. Principal component analysis (PCA) explained >98% of the variance and separated SCVB clearly from the unamended control along soil-quality and Cd axes. Strong negative correlations between Cd and fertility indicators (r = −0.86 to −0.96) indicated coupled immobilization and fertility recovery. A 5-day acute earthworm bioassay confirmed reduced soil toxicity under SCVB + Azolla, with growth inhibition reduced from 55.9% to 23.6%, mortality reduced from 26.7% to 10%, and tissue Cd accumulation reduced from 44.08 to 25.17 mg kg⁻¹ (42.9% reduction). The integrated VC + BC + Azolla system offers a cost-effective amendment-assisted Cd immobilization strategy for tropical soils, pending field validation. Full article

Heavy metal pollution remains a major global environmental challenge due to persistent ecological risks and potential threats to food safety. Microbial remediation and phytoremediation represent sustainable alternatives to conventional treatments; however, their effectiveness is strongly influenced by number of factors including nutrient availability. This review critically examines how nutritional regulation governs microbial metabolism, plant physiological responses, and rhizosphere interactions to enhance heavy metal transformation and removal. Metal bioavailability depends on type, concentration, soil pH, redox potential, and microbial processes. Interventions including fertilizers, chelating agents, inoculation with arbuscular mycorrhizal fungi and plant-growth-promoting rhizobacteria enhance phytoremediation processes through regulating plant nutrient and heavy metal uptake, while selection between ammonium/nitrate changes rhizosphere pH consequently affects plant metal uptake. Similarly, nutrients, i.e., phosphate, iron, zinc and manganese competitively affect metal uptake. Organic amendments enhance phytostabilization, especially for selenium and mercury, while enhancing chromium reduction. Sulfur-reducing bacteria precipitate metals as insoluble sulfides with 90% efficiency. In addition, soil amendments including plant-growth-promoting rhizobacteria, arbuscular mycorrhizal fungi, and metal-chelating agents can be strategically used to enhance the phytoextraction from metal from contaminated soils. We suggest that the future integration of modern approaches such as multi-omics and cisgenesis supported by artificial intelligence tools can help to accurately predict the efficiency of nutrient regulation strategies and their remediation outcomes, thereby supporting evidence-based soil management. Full article

The decline of soil organic matter in Kazakhstan due to long-term monoculture and intensive fertilizer use has increased the need for sustainable soil management strategies. This study aimed to develop a new composting technique to produce more performant organic fertilizers from cattle manure to contribute to the broader strategy to increase soil organic matter and to improve fertility in northern Kazakhstan soils. Composting experiments were conducted using oxidized coal at 5%, 10%, and 20% dosages combined with two microbial consortia, and physicochemical and microbiological parameters were monitored throughout the process. The addition of microbial consortia and oxidized coal significantly enhanced composting dynamics by accelerating the transition to the thermophilic phase and increasing microbial activity. Treated systems exhibited higher temperatures (up to 48–49 °C), greater microbial abundance, and improved nitrogen transformation, characterized by increased NH₄⁺–N accumulation followed by NO₃⁻–N formation. Organic matter degradation was more efficient in amended treatments, while oxidized coal contributed to improved moisture retention and pH stabilization. However, excessive coal addition (20%) reduced microbial activity at later stages. Among the treatments, the combination of Consortium 3 with 10% oxidized coal showed the most balanced performance, with enhanced microbial activity, efficient nutrient transformation, and stable compost maturation. These findings demonstrate that the integration of microbial consortia with oxidized coal is an effective strategy for improving composting efficiency and producing high-quality organo-mineral fertilizers, with potential for improving compost quality and nutrient stabilization, and supporting sustainable and regenerative soil management in degraded agricultural systems. Full article

Reclaiming saline–alkaline soil is critical for food security and land expansion. While paddy rice is the key pioneer crop for remediation, the soil fertility–yield relationship remains poorly understood. To optimize remediation strategies, this study evaluated soil fertility under 16 agronomic treatments—integrating irrigation quality, fertilizer regimes, and soil amendments—across three rice growth stages (tillering, heading, and maturity) in the Yellow River Delta using the minimum data set (MDS), integrated soil fertility index (SFI), and random forest models. Saline water irrigation increased soil salinity by 24.6%, while straw returning and desulfurization gypsum reduced salinity by 18.3% and 22.7%, respectively. Straw, biochar, and desulfurization gypsum significantly influenced soil organic carbon (SOC), total nitrogen (TN), inorganic nitrogen (NH₄⁺-N, NO₃⁻-N), and available phosphorus (AP), with effects varying across growth stages. Growth-stage-specific MDS indicators were significantly correlated with SFI based on the total data set (R² = 0.70, 0.65, and 0.81, p < 0.01), and stage-specific SFI was significantly positively related to rice yield. Notably, heading-stage SFI, although relatively low, explained the highest yield variance (R² = 0.51, p < 0.01) and prediction accuracy (%IncMSE = 25.22), especially under conventional NPK combined with full straw incorporation and desulfurization gypsum. These findings highlight the critical role of heading-stage soil fertility in regulating rice production, providing a targeted nutrient management blueprint for saline–alkaline paddy fields in the Yellow River Delta. Overall, this study offers a reliable scientific template to enhance yield and promote sustainable agriculture in comparable saline–alkaline paddy fields globally. Full article

Sustainable fertilization strategies are required to reduce dependence on synthetic inputs, enhance waste recycling, and improve agricultural resilience under climate change. This study evaluates the effects of wastewater-derived sludge, particularly when modified with Fe-montmorillonite, on phosphorus availability and early development of Zea mays. Methods: Germination and early growth of Zea mays were assessed under four treatments: (i) untreated soil (Control); (ii) soil amended with sludge from the Cardeal Wastewater Treatment Plant (SC); (iii) soil amended with Fe-montmorillonite-modified sludge (TechPhos, ST); and (iv) soil amended with a commercial phosphorus salt (PS). Soil characterization was conducted using XRF, XRD, and FTIR. Plant responses were evaluated through laboratory (5 days) and pot (22 days) experiments. Results: ST showed the highest performance, with a germination index of 171.7 and improved biomass, leaf development, and chlorophyll content compared to Control and SC. ST also performed similarly to or better than the commercial fertilizer (PS), indicating high phosphorus efficiency. Conclusions: The integration of nanostructured modified montmorillonite with wastewater-derived sludge represents a promising alternative phosphorus source for early maize development. Its application supports waste valorization and circular economy approaches while contributing to improved soil fertility and more sustainable nutrient management under climate change scenarios. Full article

This study examined the effectiveness of using biochar from the tanning industry as a silicon carrier to reduce trace element toxicity and improve plant nutrition in soil–plant systems. Silicon-enriched biochar was produced from chromium-free leather waste and applied in 21-day pot trials with cucumber. It contained 11.6 ± 2.3% SiO₂ and effectively served as a slow-release silicon carrier. Optimal plant growth and nutrient uptake were achieved with the application of 100% silicon without additional NPK fertilizers, demonstrating a strong positive correlation with essential trace elements such as copper and iron. Importantly, silicon fertilization significantly reduced the uptake of toxic metals such as Al, Cd, and Ti, underscoring the potential of silicon-enriched biochar for phytoremediation and sustainable crop production. Using silicon-enriched biochar from industrial leather waste thus provides a novel, sustainable strategy to improve soil fertility and plant health while repurposing waste. Future work should include long-term field trials and examine species-specific responses and management practices to scale up this approach for enhanced crop resilience. Full article

Sustainable southern highbush blueberry production in Florida is increasingly constrained by freshwater competition, variable rainfall, and the chemical vulnerability of coarse-textured and organic-based production media. Reclaimed water irrigation and biochar amendment are promising strategies for improving water use efficiency and root zone function, but their combined implications for blueberry systems remain insufficiently understood. This review synthesizes the current knowledge on blueberry production requirements, the regulatory and operational context of reclaimed water use, and the physical and chemical roles of biochar in sandy and pine bark-based substrates relevant to horticulture in Florida. Particular emphasis is placed on mechanistic links among reclaimed water chemistry, substrate properties, and root zone processes that govern salinity, pH drift, nutrient retention, and solute leaching. The literature indicates that reclaimed water can improve irrigation reliability and provide supplemental nutrients, but may also introduce sodium, chloride, boron, and other constituents, as well as alkalinity, which alter substrate chemistry and increase the risk of salinity stress and nutrient imbalance. Biochar may enhance water retention, cation exchange, and sorption capacity, but its effects are strongly dependent on feedstock, production conditions, aging, application rate, and substrate context. Overall, successfully integrating reclaimed water and biochar into blueberry systems requires substrate-specific and constituent-resolved evaluation under production conditions relevant in Florida. Full article

Fish-processing residues represent a significant environmental challenge due to their high moisture and nitrogen contents, which favor greenhouse gas (GHG) emissions during degradation. This study evaluated how different waste management strategies affect GHG emissions from fish waste, including conventional composting (Bulk), composting amended with biochar (BulkBioch), burial with soil (S), and burial with soil plus sawdust (BulkS). Daily emissions of CH₄, N₂O, and CO₂ were monitored, and cumulative emissions were modeled using generalized additive models. Composting treatments (Bulk and BulkBioch) released higher CO₂, suggesting greater microbial degradation, while burial treatments developed earlier anaerobic conditions with reduced decomposition efficiency. Bulk showed the highest cumulative CH₄ and CO₂ emissions, whereas N₂O fluxes were greater in burial methods, reaching 2.18 g N₂O kg⁻¹ TS in S. Biochar addition was associated with 15% and 10% lower CH₄ and N₂O emissions, respectively, and earlier stabilization of CH4 emissions. In global warming potential, BulkBioch presented the lowest climate impact (305 g CO₂-eq kg⁻¹ fish), followed by Bulk (338 g CO₂-eq kg⁻¹), whereas BulkS reached up to 599 g CO₂-eq kg⁻¹. The use of bulking agents in burial resulted in lower CH₄ buildup and greater nutrient retention. Overall, combining bulking agents and biochar may represent a promising strategy to mitigate GHG emissions while supporting nutrient conservation. Full article