{"title":"Fertilization and cultivation management alleviate microbial nitrogen limitation in purple soil sloping farmland: Evidence from ecoenzymatic stoichiometry","authors":"Asif Khan, Tianyang Li, Binghui He, Jianhong Song","doi":"10.1016/j.ecoleng.2024.107347","DOIUrl":null,"url":null,"abstract":"<div><p>Fertilization and cultivation management strongly affect crop productivity, alter soil nutrient availability, and influence microbial communities, leading to substantial stoichiometric imbalances. However, how these practices reflect the potential nutrient limitation of soil microbes in agricultural ecosystems remains unclear. Herein, soil samples (0–10 and 10–20 cm) from a maize crop subjected to a 15-year long-term field experiment considering five different treatments (no fertilizer + downslope cultivation, combined manure and mineral fertilizers + downslope cultivation, mineral fertilizer alone + downslope cultivation, 1.5-fold mineral fertilizer + downslope cultivation and mineral fertilizer + contour cultivation representing CK, T1, T2, T3 and T4, respectively) were deployed on a 15° purple soil sloping farmland to explore the potential microbial resource limitation using various extracellular enzyme stoichiometry (EES) approaches. Our results revealed that fertilization practices (i.e., T1, T2, T3, and T4) significantly influenced extracellular enzyme activity (EEA), particularly in T1 and T3 at the 0–10 and 10–20 cm soil depths. The mean natural logarithms of the EES ratio across the treatments were 1.23:1.34:1.00 at 0–10 cm and 1.23:1.32:1.00 at 10–20 cm depths, deviating from the overall global mean of 1:1:1, suggesting an imbalance in microbial resources. Based on the calculations of threshold elemental ratio (TER) and available resource ratios (R<sub>C:N</sub> – TER<sub>C:<em>N</em></sub> > 0), scatter plots of EES (below the 1:1 line) and vector angle (<45°) revealed that fertilization and cultivation management alleviated microbial N limitation. Furthermore, a strong homeostasis analysis of N:P and a significant increase in the N:P stoichiometry imbalance also synthetically supported N limitation from soil microbes. Heatmap correlation and random forest analysis showed that C:N, EES<sub>C:N</sub> and N:P stoichiometry imbalances were the main factors influencing microbial N limitation. Based on partial least squares path modeling (PLS-PM), soil EEA was the driving factor that induced microbial N limitation. These findings enable greater comprehension of the status of microbial resource limitation by considering the EEA stoichiometry approach under fertilization and cultivation management and provide insight into regulating soil nutrient cycling (i.e., N cycle) mediated by soil ecological processes and adjusting their management in similar intense agroecosystems worldwide.</p></div>","PeriodicalId":11490,"journal":{"name":"Ecological Engineering","volume":"207 ","pages":"Article 107347"},"PeriodicalIF":3.9000,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ecological Engineering","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0925857424001721","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ECOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Fertilization and cultivation management strongly affect crop productivity, alter soil nutrient availability, and influence microbial communities, leading to substantial stoichiometric imbalances. However, how these practices reflect the potential nutrient limitation of soil microbes in agricultural ecosystems remains unclear. Herein, soil samples (0–10 and 10–20 cm) from a maize crop subjected to a 15-year long-term field experiment considering five different treatments (no fertilizer + downslope cultivation, combined manure and mineral fertilizers + downslope cultivation, mineral fertilizer alone + downslope cultivation, 1.5-fold mineral fertilizer + downslope cultivation and mineral fertilizer + contour cultivation representing CK, T1, T2, T3 and T4, respectively) were deployed on a 15° purple soil sloping farmland to explore the potential microbial resource limitation using various extracellular enzyme stoichiometry (EES) approaches. Our results revealed that fertilization practices (i.e., T1, T2, T3, and T4) significantly influenced extracellular enzyme activity (EEA), particularly in T1 and T3 at the 0–10 and 10–20 cm soil depths. The mean natural logarithms of the EES ratio across the treatments were 1.23:1.34:1.00 at 0–10 cm and 1.23:1.32:1.00 at 10–20 cm depths, deviating from the overall global mean of 1:1:1, suggesting an imbalance in microbial resources. Based on the calculations of threshold elemental ratio (TER) and available resource ratios (RC:N – TERC:N > 0), scatter plots of EES (below the 1:1 line) and vector angle (<45°) revealed that fertilization and cultivation management alleviated microbial N limitation. Furthermore, a strong homeostasis analysis of N:P and a significant increase in the N:P stoichiometry imbalance also synthetically supported N limitation from soil microbes. Heatmap correlation and random forest analysis showed that C:N, EESC:N and N:P stoichiometry imbalances were the main factors influencing microbial N limitation. Based on partial least squares path modeling (PLS-PM), soil EEA was the driving factor that induced microbial N limitation. These findings enable greater comprehension of the status of microbial resource limitation by considering the EEA stoichiometry approach under fertilization and cultivation management and provide insight into regulating soil nutrient cycling (i.e., N cycle) mediated by soil ecological processes and adjusting their management in similar intense agroecosystems worldwide.
期刊介绍:
Ecological engineering has been defined as the design of ecosystems for the mutual benefit of humans and nature. The journal is meant for ecologists who, because of their research interests or occupation, are involved in designing, monitoring, or restoring ecosystems, and can serve as a bridge between ecologists and engineers.
Specific topics covered in the journal include: habitat reconstruction; ecotechnology; synthetic ecology; bioengineering; restoration ecology; ecology conservation; ecosystem rehabilitation; stream and river restoration; reclamation ecology; non-renewable resource conservation. Descriptions of specific applications of ecological engineering are acceptable only when situated within context of adding novelty to current research and emphasizing ecosystem restoration. We do not accept purely descriptive reports on ecosystem structures (such as vegetation surveys), purely physical assessment of materials that can be used for ecological restoration, small-model studies carried out in the laboratory or greenhouse with artificial (waste)water or crop studies, or case studies on conventional wastewater treatment and eutrophication that do not offer an ecosystem restoration approach within the paper.