{"title":"Surface-soil carbon and nitrogen mineralization under cropland, grassland, and woodland in Virginia","authors":"Alan J. Franzluebbers","doi":"10.1002/saj2.70050","DOIUrl":null,"url":null,"abstract":"<p>Long-term management of farmland can be expected to change the functioning of soil. Minimizing soil disturbance with conservation management is critical to changing surface organic matter conditions, but less is known of how canopy cover (e.g., plant species, residue quality, growth habit) may be affecting C and N properties and processes over time. A diversity of soils under different conservation land uses from 31 farms in the piedmont and mountain regions of Virginia (a warm-moist, temperate region) were sampled at 0- to 10-cm depth to assess soil C and N mineralization and associated properties. Interquartile range of surface residue N content was 76–143 kg ha<sup>−1</sup> under cropland, 102–181 kg ha<sup>−1</sup> under grassland, and 156–279 kg ha<sup>−1</sup> under woodland. Median soil-test biological activity and basal soil respiration were 39 ± 7% greater under grassland and woodland than under cropland. Median potential N mineralization was 37 ± 6% greater under grassland than under cropland and woodland. Residual soil ammonium-N, despite relatively low concentrations, was strongly associated with biologically active soil C and N properties. Apparent nitrification during laboratory incubation (g NO<sub>3</sub>-N g<sup>−1</sup> mineralized N) was high (>0.80) in all croplands, inhibited (≤0.80) in some grasslands (20% of soils), and dramatically inhibited in woodlands (85% of soils). The combination of high potential C and N mineralization and reduced nitrification may provide mechanisms for maintaining productivity while minimizing N losses to the environment in long-term conservation land uses.</p>","PeriodicalId":101043,"journal":{"name":"Proceedings - Soil Science Society of America","volume":"89 2","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/saj2.70050","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings - Soil Science Society of America","FirstCategoryId":"1085","ListUrlMain":"https://acsess.onlinelibrary.wiley.com/doi/10.1002/saj2.70050","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Long-term management of farmland can be expected to change the functioning of soil. Minimizing soil disturbance with conservation management is critical to changing surface organic matter conditions, but less is known of how canopy cover (e.g., plant species, residue quality, growth habit) may be affecting C and N properties and processes over time. A diversity of soils under different conservation land uses from 31 farms in the piedmont and mountain regions of Virginia (a warm-moist, temperate region) were sampled at 0- to 10-cm depth to assess soil C and N mineralization and associated properties. Interquartile range of surface residue N content was 76–143 kg ha−1 under cropland, 102–181 kg ha−1 under grassland, and 156–279 kg ha−1 under woodland. Median soil-test biological activity and basal soil respiration were 39 ± 7% greater under grassland and woodland than under cropland. Median potential N mineralization was 37 ± 6% greater under grassland than under cropland and woodland. Residual soil ammonium-N, despite relatively low concentrations, was strongly associated with biologically active soil C and N properties. Apparent nitrification during laboratory incubation (g NO3-N g−1 mineralized N) was high (>0.80) in all croplands, inhibited (≤0.80) in some grasslands (20% of soils), and dramatically inhibited in woodlands (85% of soils). The combination of high potential C and N mineralization and reduced nitrification may provide mechanisms for maintaining productivity while minimizing N losses to the environment in long-term conservation land uses.
农田的长期管理有望改变土壤的功能。通过保护管理尽量减少土壤干扰对改变地表有机质条件至关重要,但人们对冠层覆盖(如植物种类、残留物质量、生长习惯)如何随时间影响C和N的性质和过程知之甚少。本文对弗吉尼亚州(温暖湿润的温带地区)山前和山区31个农场在不同保护用地下的土壤进行了0- 10厘米深度的取样,以评估土壤C和N的矿化及其相关性质。土壤表层残氮含量四分位数范围分别为:耕地76 ~ 143 kg ha - 1,草地102 ~ 181 kg ha - 1,林地156 ~ 279 kg ha - 1。草地和林地土壤生物活性和土壤呼吸的中位数比农田高39±7%。草地下氮矿化电位中位数比农田和林地高37±6%。残留土壤氨氮虽然浓度相对较低,但与生物活性土壤碳氮特性密切相关。在实验室培养过程中,所有农田的表观硝化作用(g NO3-N g−1矿化N)都很高(>0.80),在一些草地(20%的土壤)受到抑制(≤0.80),在林地(85%的土壤)受到显著抑制。在长期保护性土地利用中,高潜在的碳氮矿化和减少硝化作用的结合可能提供维持生产力的机制,同时最大限度地减少对环境的氮损失。