Soil organic carbon (SOC) sequestration is crucial for sustaining agricultural productivity and mitigating climate change. However, the responses of SOC fractions, including plant-derived (PDC) and microbial necromass carbon (MNC), to long-term organic amendments remain poorly understood, particularly in fragile cropland ecosystems. To address this gap, we investigated the pathways and controlling factors of PDC and MNC accumulation under 30-year manure versus straw application in a Gray Desert soil using lignin phenol and amino sugar biomarkers. Results showed that compared to chemical fertilization, organic amendments strongly increased SOC by 124%, PDC by 428%, and MNC by 126% on average, with more pronounced increases in SOC fractions under manure relative to straw amendments. Manure amendment led to higher accrual of lignin phenol, cutin and suberin contents, and lower degree of lignin phenol degradation, reflecting enhanced physicochemical preservation of PDC, as compared to straw amendment. In contrast, straw amendment preferentially increased the relative contribution of MNC to SOC and resulted in high fungal-to-bacterial necromass ratio, highlighting efficient microbial conversion toward fungal-derived carbon stabilization. Multivariate analyses delineated the divergent pathways: manure amendment promoted PDC accumulation primarily by enhancing nutrient availability (mineral N and available P) and inhibiting the decomposition of lignin phenol. Whereas straw amendment fostered MNC accumulation via increased carbon use efficiency and hydrolase activity, both of which improved microbial efficiency and fungal dominance. Partial least squares path modeling further confirmed that nutrient availability exerted the strongest effect on PDC, whereas carbon use efficiency and hydrolase activity directly drove MNC. These findings suggest the distinct pathways of SOC accumulation triggered by manure and straw amendments, providing a mechanistic basis for designing amendment-specific soil carbon management strategies in arid croplands.
Heavy metal (HM) contamination of agricultural soils threatens global food security and human health. This review synthesizes recent advances in plant-microbe synergies for HM remediation, focusing on mechanistic detoxification pathways, nutrient interactions, and biotechnological innovations. Plant growth-promoting rhizobacteria (PGPR) enhance plant biomass by 20%–98% and reduce HM accumulation by up to 62% through biofertilization, phytostimulation, and rhizoremediation. Arbuscular mycorrhizal fungi act as structural filters, reducing metal translocation to shoots (e.g., Pb by up to 58% in soybean). Microbial consortia outperform single strains, increasing Cd phytoextraction efficiency by 30%–90% in hyperaccumulators such as Sedum alfredii. Molecularly, overexpression of phytochelatin synthase and metallothionein improves Cd and Cu tolerance 1.5- to 3-fold via enhanced reactive oxygen species scavenging and metal sequestration. Soil cation exchange capacity (CEC) is a key determinant of metal bioavailability, and microbial exopolysaccharides can modify local CEC. Emerging approaches include synthetic consortia with quorum-sensing control, microbiome engineering, and CRISPR-assisted functional validation. Nutrient management (NPK and micronutrients) further strengthens plant antioxidant defenses and restricts HM uptake. Field-scale success remains limited by soil heterogeneity, environmental fluctuations, and microbial establishment; therefore, long-term validation, predictive consortium design, and zero-waste biomass valorization are critical future directions. Integrating plant physiology, microbial biotechnology, and soil science positions microbe-assisted phytoremediation as a sustainable, circular-economy solution for HM-polluted lands.
The global shift toward biodegradable microplastics (MPs) necessitates a comprehensive assessment of their ecological risks compared to those posed by conventional MPs. However, the effects of biodegradable MPs and their particle sizes on soil ecosystems remain largely unexplored. Hence, this study investigated the distinct effects of conventional MPs (polyethylene and polyvinyl chloride) and biodegradable MPs (polybutylene adipate terephthalate and polylactic acid) across two particle sizes, on soil physicochemical properties and microbial community composition. The results demonstrated that small MPs generally increased soil moisture content (SMC) and ammonium nitrogen (NH4⁺-N), whereas large biodegradable MPs decreased SMC. Soil microbial composition was significantly altered by MPs, with the polymer type exerting a more pronounced influence than particle size. Their significant synergistic interaction (P = 0.001) highlighted the co-regulatory effect on the microbiome. Network analyses revealed that MPs destabilized the microbiome by reducing its stability and eroding competitive interaction buffers. Microbial community assembly was predominantly governed by stochastic processes (NST > 50%). Bacterial assembly was deterministically driven by soil nitrogen pools (NO3--N and NH4⁺-N) and microbial biomass, whereas fungal assembly remained decoupled from the measured soil variables. These findings underscore that the ecological effects of MP depend on both polymer type and particle size, thereby providing a theoretical foundation for comprehensively assessing the potential ecological problems and risks associated with conventional plastics and biodegradable alternatives.
Afforestation can substantially alter soil organic carbon (SOC) dynamics in drylands; however, its effects on SOC fractions remain insufficiently resolved. We investigated the effect of a 25-year afforestation chronosequence in the Kubuqi Desert on SOC fractions, including acid-hydrolyzable organic carbon (LOC) and acid-resistant organic carbon (ROC) separated by a two-step sulfuric acid hydrolysis method. Compared with the mobile dune as control, SOC increased threefold from 1.54 g kg–1 after 25 years of afforestation. LOC peaked at 2.76 g kg–1 after 15 years and then declined to 1.96 g kg–1 at 25 years. In contrast, ROC increased progressively with afforestation age, reaching 4.10 g kg–1 at 25 years and becoming the dominant SOC fraction. Consequently, the ROC/LOC ratio increased over time, indicating a shift toward greater SOC persistence under prolonged afforestation. Distinct biotic and abiotic factors regulate the two fractions, leading to contrasting responses during long-term afforestation. Multiple linear regression showed that LOC was primarily associated with litter biomass, β-D-cellobiohydrolase activity, and specific bacterial ecological modules, whereas ROC was mainly linked to litter biomass, soil C/N ratio, and fungal ecological modules. Overall, long-term afforestation in temperate deserts enhances both SOC accumulation and persistence, highlighting its value as a sustainable strategy for carbon sequestration in dryland restoration.
This study addresses a critical methodological gap in spatial prediction of soil properties by evaluating strategies to optimize sampling design and intensity. We first conducted a systematic review of digital soil mapping studies (2000-2024) to characterize current sampling practices. Conditioned Latin hypercube sampling (CLHS; 71% of the total studies) and simple random sampling (59%), followed by stratified random sampling (33%) and spatial coverage sampling (23%), were the most prevalent designs. However, only 6% of the reviewed studies used quantitative pre-modeling metrics to assess the covariate-space representativeness of the sampling designs. To address this limitation, we developed and tested a divergence-based framework that evaluates sampling designs in covariate space using two information-theoretic representativeness metrics, Bhattacharyya distance (BD) and Kullback-Leibler divergence (KLD). We applied the framework across four study sites representing field, farm, and landscape scales, and identified cost‑efficient sampling ranges. CLHS consistently achieved the lowest BD and KLD, indicating stronger representation of the covariate distribution covered by the existing measured sampling campaigns. The optimal sampling density varied across sites and depended on covariate-space heterogeneity and spatial autocorrelation structure. At three of the four case-study sites, optimal sample sizes were 28-29% of the existing sampling efforts, corresponding to cost reductions of 71-72%. Moreover, we demonstrated that BD/KLD-based pre-modeling covariate-space representativeness evaluation aligns with the accuracy stabilization of Random Forest prediction of soil organic matter. The proposed framework provides a practical tool that leverages pre‑modeling representativeness to guide optimal soil sampling for spatial prediction, supporting applications in precision agriculture and sustainable soil management.
The increasing emissions of anthropogenic CO2 require the development of effective carbon management technologies to mitigate global warming. This study explores the application of biochar derived from agricultural residues as a CO2 adsorbent. Biochar is a porous carbonaceous material widely studied for soil amendment due to its ability to immobilize pollutants, including CO2. However, owing to its limited surface area and porosity, pristine biochar exhibits restricted CO2 adsorption capacity. To enhance its performance, the surface properties of biochar were modified using CO2 as a reactive medium. The use of CO2 served two objectives: (1) improving biochar surface characteristics and (2) enhancing the overall sustainability of the pyrolysis process. CO2-assisted pyrolysis of walnut shell (WNS) at 700°C induced morphological modification of the biochar. Consequently, the specific surface area of the biochar increased 2.55-fold at 700°C compared to conventional conditions, yielding a CO2 adsorption capacity of 87.88 mg g-1. This is 1.20-fold higher than that of the biochar produced under N2. CO2 adsorption-desorption cycling tests demonstrated the stability of the biochar over multiple cycles. Utilization of the gaseous and liquid pyrolysates, generated during biochar production, as alternative fuels has the potential to further improve sustainability. The introduction of CO2 during WNS pyrolysis enhanced syngas production through the direct conversion of CO2 to CO, resulting in a 5.22-fold increase in syngas yield. These results indicate a potential reduction in CO2 emissions of 1.75 kg CO2-eq. kgWNS-1, highlighting the dual benefits of CO2-assisted pyrolysis for the simultaneous production of carbon-sequestering materials and renewable energy.
With the rapid development of protected agriculture, continuous cropping obstacles (CCOs) have become prominent, severely restricting the sustainable development of the sector. In this review, the mechanism of crop failure in protected agriculture is discussed in depth, including the deterioration of soil physicochemical properties, such as soil acidification, salinization, and nutrient imbalance, and the imbalance of soil microbial community structure, with an increase in harmful microorganisms and a decrease in beneficial microorganisms. Moreover, the accumulation of self-toxic substances (the core of other factors) and unreasonable agricultural management practices negatively impact the growth of crops. In addition, mitigation strategies for CCOs, including rational crop rotation, improved cultivation systems, rational fertilization, soil sterilization, soil amendments, variety breeding, and crop-targeted genetic engineering, are summarized. This review comprehensively summarizes the recent research progress on mechanisms of CCOs and mitigation strategies in protected agriculture. It also discusses the synergistic interactions among the multiple factors driving CCOs, thereby providing a theoretical and practical foundation for mitigating succession-related obstacles and supporting the sustainable development of protected agriculture.
Soil Cadmium (Cd) pollution has become an increasingly serious issue. Cadmium is a toxic, non-essential element for plants, and even at low concentrations, it can have irreversible effects. The problem of excessive heavy metals in soil has attracted significant national attention. Sulfur (S), an essential element for crop growth, plays a key role in regulating the bioavailability of heavy metals in soil. However, the mechanisms by which S nutrition regulates Cd uptake, particularly through microbe-mediated transformations of S forms in the rhizosphere, remain unclear. Therefore, managing S nutrition in soil has important practical implications for ensuring agricultural productivity and preventing excessive accumulation of heavy metals in crops. Investigating the effect of S on Cd migration and accumulation in the soil-plant system is vital for guiding food security in moderately and lightly Cd-contaminated farmland, as well as for supporting the use of S to immobilize soil-bound Cd and reduce its uptake by plants.
Dromedary camel value chains present significant opportunities for attracting investors and reinvesting in rangeland restoration. Despite declining productivity and limited development of dromedary milk products, the sector remains crucial for its resilience in arid ecosystems and socioeconomic importance in the southern regions of Tunisia. The authors take a reflective approach to explore the potential of dromedary value chains in Tunisia. The study highlights the dual benefits of investing in these value chains, to drive economic development and environmental conservation, by employing a combination of desk review, key informant interviews (n = 11), and SWOT analysis. The sector assessment reveals statistical complexities and fluctuations in milk and meat production. Key informant interviews gathered insights from breeders, processors, traders, policymakers, and experts on challenges, opportunities, and feasibility of investment and rangeland restoration initiatives. The SWOT analysis identified internal strengths and weaknesses in the dromedary sector and external opportunities and threats. Recommendations include modernizing dromedary camel farming (settled, semi-intensive systems) and herding practices (nomadic and extensive pastoralism), transitioning to sustainable breeding and fattening, improving biosecurity and veterinary services, and enhancing feed management and genetic improvement. Strengthening value chains involves investing in processing infrastructure, marketing, product diversification, and structured milk collection networks. Integrated rangeland management includes cultivating fodder crops and protecting vegetation cover. Governance improvements through dromedary breeder associations, stakeholder engagement, and effective regulation are also crucial. Findings may inform policymakers, development agencies, financial institutions, and private investors about the dromedary sector’s potential in Tunisia, guide targeted interventions for growth and sustainability, and provide pathways to rangeland restoration. By addressing challenges and leveraging unique capabilities, dromedary value chains can drive economic development, environmental conservation, and social resilience in the region.
Antibiotic resistance (ABR) is recognised as a critical One Health challenge globally, threatening human, animal, and environmental health. In Senegal, pastoral livestock systems provide the bulk of animal-source foods, yet little evidence exists on antibiotic use practices that may foster ABR. This study aimed to investigate antibiotic use in pastoral farming in Kaffrine, Senegal, and its implication for ABR transmission across the food system. A cross-sectional survey was conducted between March and April 2023 among 220 pastoralists in Kaffrine. Participants were selected using Schwartz’ formula, and data were collected through face-to-face interviews using an adapted CGIAR AMUSE Livestock questionnaire, translated into local languages. Data were analysed descriptively with R Studio (version 4.3.2.). Respondents were predominantly men (86.8%), with limited formal education (81%). Common animal diseases included Plague of small ruminants (52.7%), Lumpy skin disease (39%), and Pasteurellosis (28.1%). Antibiotic use was extensive, dominated by tetracyclines (88.6%), followed by penicillins (10.4%). Usage was mainly for treatment (94%), prevention (42.7%), and growth promotion (33%). Administration was carried out by para-veterinarians (50.9%) and untrained auxiliaries (45.9%), while 40.5% of pastoralists practiced self-medication for their animals. Although 65.5% recognised ABR as a public health issue, only 5.5% adopted reduction strategies, primarily vaccination. Notably, 65.5% administered antibiotics to lactating animals, and only 55% observed withdrawal periods before slaughter, averaging 4 days. Non-compliance, inadequate dosages, and treatment interruptions were frequent. Despite awareness of ABR, misuse of antibiotic remains generalized in pastoral systems in Kaffrine, posing significant food safety and public health risks. Expanding access to veterinary services, strengthening vaccination programmes, and enhancing antibiotic stewardship through an increased number of veterinary drug inspectors and adequate financial resources for effective monitoring and regulatory oversight are critical to mitigating ABR and safeguarding sustainable food systems.
In modern intensive agriculture, nitrogen (N) fertilizers are applied at high rates to enhance crop yield. However, the application of excessive fertilizers often exceeds crop uptake capacity, resulting in significantly reduced nitrogen use efficiency. This imbalance leads to substantial nitrate accumulation in soil-plant systems, posing severe risks: environmentally, it causes groundwater pollution via leaching; physiologically, it impacts crop quality and growth; and toxicologically, it threatens human health. This review systematically elucidates the dynamics of nitrate accumulation, categorizing sources and analyzing key driving factors, including environmental conditions and the regulation of nitrate transporters. Crucially, we critically evaluate the hazards and benefits of nitrate to both plants and humans, providing a balanced toxicological perspective. Furthermore, integrated mitigation strategies are outlined, ranging from optimizing fertilizer types and managing stabilized organic amendments to implementing runoff remediation technologies. Future perspectives emphasize the transition towards precision agriculture, utilizing sensors and Decision Support Systems (DSS) to align N input with crop demand curves, thereby balancing high productivity with environmental safety.
Climate warming-induced disruptions to soil microbial communities have been shown to affect the stability of soil carbon pools within terrestrial ecosystems, yet how these shifts regulate changes in soil organic carbon (SOC) and microbial assembly remains poorly understood. Here, we collected paddy soil samples during the drained fallow phase from thirteen regions across China, and incubated them under five temperature regimens, to investigate how temperature shapes the assembly of bacterial generalists and specialists and its consequences for SOC changes. Our findings revealed a contrasting response to different thermal regimens between generalists and specialists in paddy soils. Generalists showed reduced diversity at higher static incubation temperatures, whereas specialists displayed the opposite trend. Simultaneously, a temperature-dependent divergence in assembly mechanisms between bacterial specialists and generalists, with 15 °C representing the point of maximum deterministic selection for specialists but maximum stochastic processes for generalists. Habitat generalists demonstrated greater network robustness than specialists, while functional capacities related to carbon metabolism were enhanced for both groups under different incubation temperatures. Among the bacterial properties examined, network interactions and diversity of specialists were the strongest biotic predictors of short-term SOC changes, while soil type and nutrients remained the dominant overall drivers. This study provides a mechanistic underpinning for the process of bacterial community assembly in soil carbon metabolism.
Cellulose, the predominant polysaccharide in crop straw, is a key source of carbon (C) input to agricultural soils. However, the effect of different fertilization regimes on the microbial groups responsible for cellulose degradation and subsequent incorporation into necromass is unknown. In this study, Ultisol soils subjected to 27-year application of mineral fertilizers (nitrogen, phosphorus, and potassium; NPK), pig manure combined with mineral fertilizers (NPM), and no fertilizers (Control) were incubated with 13C-labeled cellulose for 30 days. Microbial communities actively assimilating cellulose-derived carbon during decomposition and necromass formation were analyzed using biomarker stable-isotope probing (phospholipid fatty acid/amino sugar-SIP). The incorporation of cellulose-derived 13C into microbial necromass in NPM-treated soil reached 82.1 mg C kg–1, which was significantly higher than in NPK-treated and Control soils (35.0−74.4 mg C kg–1; P < 0.05). NPM treatment resulted in a higher abundance of 13C-labeled saprotrophic fungi and a higher fungi-to-bacteria ratio (1.98), thereby facilitating faster decomposition of cellulose and increasing microbial 13C utilization and necromass accumulation efficiency, especially for fungal necromass. In contrast, cellulose-derived 13C in NPK soil was markedly integrated into bacterial necromass, because the reduced abundance of saprotrophic fungi hindered cellulose breakdown and promoted Gram-positive bacteria proliferation. Overall, long-term application of manure shifted microbial community structure by increasing the abundance of saprotrophic fungi and modified microbial strategies for transforming cellulose into necromass, thereby influencing the storage and stabilization of soil organic C. Our findings underscore that long-term manure application promotes the fungal-mediated transformation of cellulose-derived 13C into microbial necromass.
Conventional soil washing agents for potentially toxic elements (PTEs) remediation face challenges such as low selectivity, secondary pollution, and soil fertility degradation. This study proposes a sustainable two-step co-washing strategy combining wood vinegar (WV, 80%) and FeSO4 (0.6 mol L-1) to synergistically enhance iron oxide dissolution and PTEs removal. This novel strategy introduces an unprecedented acid-reduction synergy that overcomes the limitations of conventional washing agents. For Cd, Pb, and Zn in two contrasting soils (clay loam vs. sandy loam), sequential WV-FeSO4 treatment achieved 82.46%–83.92%, 43.34%–51.21%, and 61.35%–67.80% removal efficiencies, respectively—surpassing single-agent washing by 12.00%–26.01%. Mechanistically, the enhanced dissolution of the metal ions from the soil may be attributed to the reduction of the soil minerals by the addition of the Fe2+ and increased soil acidity induced by the hydrolysis of the Fe3+ ion. Our findings provide direct evidence for a Fe2+-assisted dissolution pathway, which is key to unlocking PTEs from resistant soil fractions. Post-remediation soil retained 22.68–24.42 g kg-1 organic carbon, with catalase activity increasing by 9.89%–11.37%, and the abundance of Firmicutes or Bacteroidota rising 2.74–4.21-fold. Despite pH reduction (7.42→6.08; 6.22→4.17), residual PTEs stability (reduced partition index IR: 0.37–0.60) and soil structure integrity (SEM-EDS confirmed no particle collapse) were maintained. This work establishes a green paradigm for multi-PTE remediation through acid-reduction synergy, balancing efficiency with preservation of soil health.
Iron-based metal-organic frameworks (Fe-MOFs) synthesized with oxalic acid (OA) show great promise as controlled-release fertilizers (CRFs) for enhancing nutrient use efficiency. Incorporating a second nutrient metal into these OA-MOFs could provide a more balanced nutrient supply, yet the structural characteristics and agronomic performance of bimetallic OA–MOFs remain insufficiently explored. Herein, we synthesized three bimetallic MOFs—OA1 (Fe/K), OA2 (Fe/Ca), and OA3 (Fe/Zn)—to evaluate their potential as multifunctional CRFs. Although Fe was the primary coordinating metal, the introduction of a second metal (K, Ca, or Zn) significantly influenced the composition and structure of the MOFs. In saline-alkali soil, all three MOFs enabled the sustained release of compound nutrients (N, P, Fe, and the respective secondary metal) over 30 d, with release rates following the order OA2 > OA3 > OA1. The release kinetics were best described by the Higuchi and Ritger-Peppas models. The MOFs also effectively ameliorated soil conditions, reducing salinity by up to 10.11% and lowering pH by up to 1.96 units, with OA3 (Fe/Zn) exhibiting the strongest effect. Furthermore, OA3 demonstrated a high capacity for NaCl adsorption (qe = 37.62 mg g-1), which followed pseudo-first-order kinetics and the Langmuir isotherm model, indicating a spontaneous and endothermic process. Pot and field experiments further demonstrated that OA2 and OA3 significantly enhanced the growth of bok choy and maize. Notably, OA3 increased maize yield by 47.2% in saline-alkali soil without adversely affecting seed germination. Collectively, these findings underscore the potential of bimetallic OA-MOFs as a novel class of multifunctional CRFs, offering a promising strategy for the efficient utilization of saline-alkali soils.
