Proceedings - Soil Science Society of America最新文献

{"title":"Mechanistic role of biochar as a geobiochemical amendment: Mitigating abiotic stress and enhancing soil–plant interactions","authors":"Waqas Haider,&nbsp;Qudrat Ullah,&nbsp;Muhammad Qasim,&nbsp;Md. Nahid Mahmud,&nbsp;Irfan Haidri,&nbsp;Muhammad Ali Amir,&nbsp;Rashid Abbas Khan,&nbsp;Tauqeer Ahmed Qadri,&nbsp;Amjid Khan","doi":"10.1002/saj2.70339","DOIUrl":"https://doi.org/10.1002/saj2.70339","url":null,"abstract":"<p>Abiotic stressors, including drought, salinity, and heavy metal contamination, pose escalating threats to global food security, challenges further exacerbated by climate change and progressive soil degradation. As a strategic geochemical amendment, biochar is increasingly proposed to enhance soil resilience and agricultural sustainability, directly supporting sustainable development goal (SDG) 2 (Zero Hunger) and SDG 13 (Climate Action). This review critically evaluates biochar in stress mitigation, focusing on production principles, soil physicochemical adjustments, and changes in the soil-plant microbiome and soil–plant–microbe interactions. Specifically, we synthesize data demonstrating biochar's multifaceted efficacy: regulating ion homeostasis to reduce Na⁺ uptake by 20%–40% under saline conditions, enhancing water use efficiency by 15%–30% in arid environments, and immobilizing heavy metals to reduce cadmium (Cd) accumulation by 25%–50%. These synergistic soil–plant interactions further contribute to SDG 6 (Clean Water and Sanitation) and SDG 15 (Life on Land). However, significant challenges remain regarding feedstock variability, dosage optimization, and long-term field stability. Furthermore, performance discrepancies under combined multi-stress scenarios underscore the urgent need for standardized biochar formulations. Integrating biochar into precision frameworks offers a promising geobiochemical frontier for modulating multi-stress crop resilience and shifting soil–plant–microbe dynamics toward climate-adaptive landscapes. Such advancements are essential for ensuring global food security for a projected population of 9.7 billion by 2050.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70339","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148942381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Saline but not sodic: Groundwater quality and irrigation suitability in the traditional oasis of El Guettar (Gafsa, southern Tunisia)","authors":"Amor Ben Garali,&nbsp;Feyda Srarfi,&nbsp;Fatma Hmiden","doi":"10.1002/saj2.70341","DOIUrl":"https://doi.org/10.1002/saj2.70341","url":null,"abstract":"<p>In an arid pre-Saharan climate where rainfall is scarce, agricultural activity in the traditional oasis of El Guettar relies heavily on groundwater for irrigation. The quality of these water resources is influenced by local hydrogeology, geological structures, topography, rainfall, evaporation, interactions between rocks and water, and irrigation methods. This study provides an assessment of groundwater quality and its suitability for irrigation using six water samples collected from five wells and one borehole. We measured physicochemical parameters (pH, temperature, electrical conductivity, and total dissolved solids) and major ion concentrations (calcium, magnesium, sodium, potassium, bicarbonate, chloride, and sulfate). Water quality was evaluated using five indices: sodium adsorption ratio (SAR), cation ratio of soil structural stability (CROSS), residual sodium carbonate (RSC), sodium percentage (Na%), permeability index, and magnesium hazard (MH), along with Wilcox and Riverside (United States Salinity Laboratory) diagrams. The results reveal that the groundwater is very saline but not sodic, with SAR values below 10 and negative RSC values for all samples, indicating no risk of soil sodification. &gt;66% of the samples show a high risk of soil structure disintegration, according to CROSS. The Wilcox diagram and electrical conductivity measurements indicate very high salinity, requiring salt-tolerant crops and effective drainage. Only wells P1 and P4 offer optimal quality, while the others (P2, P3, P5, and P6) have excess magnesium (high MH &gt; 50), which can be corrected by gypsum, a locally abundant resource. Thus, appropriate management can maintain the productivity of this oasis despite the water salinity.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148942541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal dynamics of soil biological properties under long-term cereal rye cover cropping in a no-till corn–soybean rotation in Southeastern Indiana","authors":"Anshu Siwach,&nbsp;Eileen J. Kladivko,&nbsp;Benjamin Goller,&nbsp;Ratul Baishya,&nbsp;Yichao Rui","doi":"10.1002/saj2.70325","DOIUrl":"https://doi.org/10.1002/saj2.70325","url":null,"abstract":"<p>Cover crops are widely used in corn (<i>Zea mays</i> L.)–soybean (<i>Glycine max</i>) systems to improve soil health, yet seasonally dynamic responses of soil biological properties to long-term cover cropping remain not fully understood, particularly in the low-organic matter Alfisols of the eastern Corn Belt. We evaluated the effects of more than a decade of cereal rye (<i>Secale cereale</i> L.) cover cropping on soil biological properties in a no-till corn–soybean rotation in southeastern Indiana in a field experiment established in 2011. Soil samples were collected at two depths (0–10 and 10–20 cm) during fall, spring, and summer in 2023–2024 and analyzed for microbial biomass carbon and nitrogen (soil microbial biomass carbon [SMBC] and soil microbial biomass nitrogen [SMBN]), potentially mineralizable carbon (PMC), permanganate-oxidizable carbon (POXC), autoclaved citrate-extractable (ACE) protein, and enzyme activities associated with carbon (C), nitrogen (N), and phosphorus (P) cycling. Cover cropping increased SMBC, SMBN, and PMC, with treatment effects varying by season and soil depth. Cover crop effects on microbial biomass and PMC were most pronounced during spring and were largely confined to the 0–10 cm. In contrast, POXC, ACE protein, and enzyme responses were indicator-specific; acid phosphatase activity increased under cover cropping and peaked in summer, whereas POXC, ACE protein, and activities of β-glucosidase and N-acetyl-β-glucosaminidase showed limited overall treatment effects. These findings indicate that long-term cereal rye cover cropping enhances biologically mediated C and nutrient cycling in no-till systems, with effects expressed in a seasonally and vertically stratified manner rather than as uniform, sustained increases.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70325","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148942379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cropping system and nitrogen fertilization modulate soil enzyme kinetics","authors":"A. A. Khaleel,&nbsp;M. L. Thompson,&nbsp;M. D. McDaniel","doi":"10.1002/saj2.70336","DOIUrl":"https://doi.org/10.1002/saj2.70336","url":null,"abstract":"<p>The decomposition of soil organic matter and nutrient cycling are largely mediated by extracellular enzymes, yet the effect of soil management on enzyme kinetic (Michaelis constant [<i>K</i>_m] and maximum velocity [<i>V</i>_max]) remains poorly understood. We investigated the long-term effects of three cropping systems—annual maize (<i>Zea Mays</i>)–soybean (<i>Glycine max</i> (L) Merr.) (CS), unfertilized prairie (UPr), and fertilized prairie (FPr)—on the kinetic parameters of β-glucosidase(BGase) and leucine-aminopeptidase (LAPase). We focused our research on two contrasts: (1) The comparison of enzyme activities in a fertilized perennial cropping system with an annual rotational cropping system (FPr vs. CS) and (2) the effect of fertilizer nitrogen (N) on enzyme activity in a perennial cropping system (FPr vs. UPr). First, we hypothesized that perennial roots would enhance soil biological activity in FPr and increase both enzymes’ <i>V</i>_max and <i>K</i>_m compared to CS; and second that N fertilizer added to FPr would decrease LAPase <i>V</i>_max due to decreased microbial demand for N. In partial support of our first hypothesis, FPr increased BGase <i>V</i>_max by 85% compared to CS, but had no effect on LAPase <i>V</i>_max. Supporting H2, fertilizing prairie significantly decreased LAPase <i>V</i>_max by 36% compared to UPr, likely due to either lower N demand or indirectly via long-term changes in prairie plant species. Overall, for both enzymes, however, <i>K</i>_m was insensitive to long-term management. The diversified, perennial cropping system increased soil microbial biomass regardless of fertilizer application, and the activities of carbon- and N-acquiring enzymes depended on whether or not the perennial crop was fertilized.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70336","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148942539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative analysis of organophosphorus esters, novel brominated flame retardants, and organic pesticides on soil eco-enzymatic activity","authors":"Yu Yang,&nbsp;Hui Huang,&nbsp;Haixia Tian,&nbsp;Yuanwei Wu,&nbsp;Peimei Guan,&nbsp;Ruiyue Lu,&nbsp;Ziquan Wang,&nbsp;Megharaj Mallavarapu,&nbsp;Wenxiang He","doi":"10.1002/saj2.70326","DOIUrl":"https://doi.org/10.1002/saj2.70326","url":null,"abstract":"<p>To evaluate the ecological risks of emerging contaminants (ECs) in soils, we systematically investigated the effects of 28 ECs, including organophosphorus esters (OPEs), novel brominated flame retardants (NBFRs), and organic pesticides on five key soil enzyme activities: β-glucosidase, urease, alkaline phosphatase, arylsulfatase (ARS), and fluorescein diacetate hydrolase (FDA-H). Among the enzymes tested, ARS activity was enhanced by nearly half of the ECs (13 out of 28), especially by OPEs. However, enzyme kinetic analyses revealed that reduced substrate affinity offsets the increased maximal reaction velocity, resulting in unchanged or even reduced catalytic efficiency. In contrast, FDA-H activity was generally inhibited, exhibiting the greatest response ratio (0.115), indicating that it was the most sensitive enzyme to pollutant exposure. Notably, 2,4,6-tribromophenol inhibited ARS via linear mixed inhibition mechanism, with ecological dose (ED₁₀) values ranging from 7.53 to 13.9 mg kg⁻¹, whereas isoprocarb suppressed FDA-H via competitive inhibition, with ED₁₀ values of 3.97–6.58 mg kg⁻¹. Based on the average magnitude of effects on soil enzymatic activities (mean score: 0.113) and the functional index (0.148), NBFRs potentially pose greater ecological risks to overall soil functionality than OPEs or the evaluated organic pesticides. These findings highlight the significant and diverse impacts of ECs on critical soil microbial functions and emphasize the urgent need for further investigation into the ecological effects of NBFRs in terrestrial environments.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating agronomic performance and environmental benefits of conservation practices in subtropical pasture systems","authors":"Julian Avila Bernal,&nbsp;Maria Lucia Silveira,&nbsp;Joao M. B. Vendramini,&nbsp;Jehangir H. Bhadha,&nbsp;David A. Foster,&nbsp;Nikitha R. Kovvuri,&nbsp;Namrata Ghimire","doi":"10.1002/saj2.70329","DOIUrl":"https://doi.org/10.1002/saj2.70329","url":null,"abstract":"<p>Sustainable agriculture is key to global food security and ecosystem services, including climate mitigation. However, the benefits of conservation practices in grassland systems remain poorly understood. This 2-year field study evaluated the effects of conservation practices on subtropical perennial grass pasture productivity, soil health indicators, and greenhouse gas (GHG) emissions responses. Treatments included cover crop (overseeded annual and perennial legumes), nutrient management (organic or inorganic nitrogen [N]), and soil amendments (biochar and basaltic rock). Nitrogen fertilization increased forage productivity, while other treatments showed limited agronomic benefits. Establishing annual or perennial legumes in grass-dominated systems proved challenging, indicating that improved establishment strategies are needed for successful integration. Most practices had limited short-term effects on soil carbon (C), soil health indicators, and GHG emissions. Biochar had the greatest impact, increasing soil C stocks (82 vs. 26 Mg C ha⁻¹) and soil water retention (0.30 vs. 0.06 m³ m⁻³) at the 0- to 10-cm depth. However, elevated soil phosphorus (P) following biochar application may pose environmental risks in soils susceptible to P losses. Overall, environmental conditions were the primary drivers of GHG fluxes. These findings indicate that conservation practices in subtropical pastures require long-term, site-specific implementation before improvements in soil health, agronomic performance, and environmental outcomes can be expected.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Altitudinal patterns of particle size distribution and Atterberg limits in subtropical soil profiles of South China","authors":"Yuyun Li,&nbsp;Qiuxia Su,&nbsp;Caile Luo,&nbsp;Wencong Liang,&nbsp;Feng Lu,&nbsp;Weisheng Luo,&nbsp;Qiuyue Tang,&nbsp;Zhiwei Qin,&nbsp;Xionghui Liu,&nbsp;Yusong Deng","doi":"10.1002/saj2.70333","DOIUrl":"https://doi.org/10.1002/saj2.70333","url":null,"abstract":"<p>Soil particle size distribution (PSD) and Atterberg limits are critical indicators reflecting soil structural stability and plasticity. Clarifying their altitudinal and vertical differentiation patterns and coupling mechanisms is essential for revealing the hydrological and ecological functions of mountain soils regarding water retention and erosion resistance. However, the gradient differentiation of soil particle structure and plastic properties remains poorly understood in subtropical mountainous regions. In this study, soil profiles across seven altitude gradients were investigated to explore the altitudinal and vertical variations in PSD, fractal dimensions, and Atterberg limits, and further reveal the regulatory effects of particle structure on soil plastic properties. The results showed that mountain soils in the study area were dominated by silt particles with the lowest clay content. Clay content and monofractal dimension exhibited unimodal variations with altitude and soil depth. Multifractal characteristics could precisely characterize the heterogeneity of soil particle composition. Atterberg limits show significant altitudinal differentiation (<i>p</i> &lt; 0.05) with a unimodal trend primarily controlled by clay content. Driven by topsoil organic matter accumulation and clay eluviation-illuviation, Atterberg limits peak in topsoil and illuvial horizons. Moreover, significant coupling relationships existed between Atterberg limits, particle composition, and multifractal parameters, indicating that particle structure serves as a core factor regulating the vertical and altitudinal differentiation of mountain soil physical properties. This study adopts multifractal analysis to quantify altitude-dependent PSD variation and clarify the particle-regulated spatial heterogeneity of soil plasticity, providing theoretical insights into soil and water conservation in subtropical mountainous regions.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Limited evidence for soil enzyme activities mediating C:N discrepancies between microbial biomass and organic matter in year 145 of a maize-based agroecosystem experiment","authors":"Tianze Song,&nbsp;Ezra Moses,&nbsp;Rosa Elena Ibarra López,&nbsp;Chammi Attanayake,&nbsp;Taylor B. Berkshire-Akers,&nbsp;Andrew John Margenot","doi":"10.1002/saj2.70320","DOIUrl":"https://doi.org/10.1002/saj2.70320","url":null,"abstract":"<p>Soil microbial biomass (MB) generally exhibits a narrower C:N than soil organic matter (SOM), creating a stoichiometric discrepancy hypothesized to be reconciled in part by C- and N-acquiring enzyme activities. We used soils from an at-equilibrium long-term experiment to evaluate the degree to which MB C:N plasticity and enzyme activities explained MB–SOM C:N discrepancies among total SOM, particulate organic matter (POM), and mineral-associated organic matter (MAOM) at 0- to 17- and 17- to 30-cm depths. MB C:N increased with depth from 8.6 to 11.7, whereas total SOM and MAOM C:N were similar (∼13), and POM maintained higher C:N (∼19–20) between depths. MB C:N was unrelated to total SOM C:N, but increased with MAOM C:N at surface depth and declined with POM C:N at subsurface depth. Residual analyses identified limited relationships between enzyme activities and total SOM or POM C:N discrepancies. MAOM C:N residuals showed more frequent and negative relationships, which did not support enzyme-mediated reconciliation of stoichiometric discrepancies. In contrast, fertilization-induced changes in C- and N-acquiring enzyme activities were positively associated, but were more strongly expressed through total N-acquiring enzyme activity under manure and certain aminopeptidase activities under synthetic fertilization. Overall, our results demonstrate that interpreting MB C:N in maize-based agroecosystems should consider SOM fractions and exert caution in the selection of soil enzyme activities used to infer limitation, because widely used soil enzyme activity ratios alone (i) provide limited inferences to microbial nutrient limitation and (ii) do not appear to reflect activities of related soil enzymes.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70320","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning insights into long-term soil fertility legacy and seasonal weather effects in corn–soybean rotation","authors":"Matias Lucero,&nbsp;Eric Adee,&nbsp;Dorivar Ruiz Diaz,&nbsp;Tina Sullivan,&nbsp;Gaurav Jha,&nbsp;Logan Simon,&nbsp;Deepak R. Joshi","doi":"10.1002/saj2.70334","DOIUrl":"https://doi.org/10.1002/saj2.70334","url":null,"abstract":"<p>Multiple factors, such as accumulated fertility legacies, crop rotation, soil properties, and seasonal weather variables, complicate long-term studies due to their nonlinearity and interdependencies. Therefore, we hypothesize that a machine learning (ML)-based data analytics approach can help address this gap and identify the most influential variables associated with the long-term yields of corn (<i>Zea mays</i>) and soybeans (<i>Glycine max</i>). The objectives of the study were to identify the key soil and weather variables associated with corn and soybean yield variability, to assess crop-specific variables, and to evaluate the robustness of a single nonlinear ML approach for long-term yield prediction. For that purpose, a 43-year soil fertility experiment was conducted in Topeka, KS, with 20 combinations of nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates. Variables such as temperature, precipitation, irrigation, soil pH, soil P and K levels, soil texture, and N–P–K fertilization rates (both annual and cumulative) were combined into a Random Forest (RF) ML model. For corn, N fertilizer, soil P, and soil pH were important variables associated with yield variability, whereas soybean yields were more associated with weather variables, particularly rainfall, evapotranspiration, and soil P. The RF model performed well for corn (<i>R</i>² = 0.81, RMSE = 1449 kg ha⁻¹) and soybean (<i>R</i>² = 0.74, RMSE = 527 kg ha⁻¹) yield estimation. These results demonstrate that ML models can help identify key predictors of yield variability and provide robust yield estimates, thereby supporting improved long-term crop management decisions.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70334","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil carbon stocks, microbial stoichiometry, and enzyme activities across a 54-year chronosequence of continuous maize versus maize–soybean rotations","authors":"Pei-Chen Lee,&nbsp;Connor N. Sible,&nbsp;Frederick E. Below,&nbsp;Maria B. Villamil,&nbsp;Andrew J. Margenot","doi":"10.1002/saj2.70330","DOIUrl":"https://doi.org/10.1002/saj2.70330","url":null,"abstract":"<p>Crop rotational diversity is hypothesized to enhance soil organic carbon (SOC) surface stocks, yet the long-term SOC response to maize (<i>Zea mays </i>L.)–soybean [<i>Glycine max</i> (L.) Merr.] (MS) relative to continuous maize (MM) is inconsistent despite the greater residue C inputs in MM. We quantified SOC concentration and stock, microbial biomass carbon (MBC) and nitrogen (MBN), mineralizable C, and β-glucosidase, cellobiohydrolase, phenol oxidase, and peroxidase activities at 0- to 15-cm and 15- to 30-cm depths in 19-, 26-, 41-, and 54-year rotation durations on Argiudolls across central-north Illinois. Surface (0–15 cm) SOC stocks were similar between MS and MM across 19–54 years. The logarithmic attenuation of absolute relative annual (RAD_abs, |% year⁻¹|) and absolute annual (AD_abs, |Mg C ha⁻¹ year⁻¹|) SOC stock differences suggested a trajectory toward equilibrium over half a century. Soil β-glucosidase activity and MBC:MBN converged between rotations by 19 years, equilibrating earlier than SOC stock differences. Microbial biomass (MBC and MBN) was largely similar between rotations. Higher residue C inputs in MM increased mineralizable C and cellobiohydrolase and peroxidase activities, which, along with similar SOC stocks as MS, suggests that the greater residue C inputs were offset by increased decomposition. Rotation effects on microbial biomass and enzyme activities were largely limited to the 0- to 15-cm depth and attenuated at 15- to 30-cm depth. Collectively, our findings indicate that microbial physiological adaptations, specifically stoichiometric constraints and enzymatic shifts toward accelerated decomposition, decouple residue input quantity from long-term SOC stocks and lead to equilibrium.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"90 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}