Data from: Organic production reduces subsurface nitrate leaching and maintains crop yields in US Mollisol

Organic production aims to diversify crop rotation and use organic fertilizer sources to build soil fertility and improve soil health indicators. This data evaluates the impact of organic farming on water quality in artificially drained midwestern Mollisols of central Iowa. This 7-year study compares tile nitrate loss and yields under three cropping systems: (1) conventional corn (<i>Zea mays</i> L)-soybean (<i>Glycine max</i> L.), (2) organic corn–soybean–oat (<i>Avena sativa</i> L.)/alfalfa (<i>Medicago sativa</i> L)–alfalfa, and (3) organic perennial pasture. Nitrogen (N) fertilization consisted of sidedress urea ammonium nitrate for conventional corn (168 kg N ha⁻¹) and spring-applied composted manure for organic corn (168 kg N ha⁻¹) and oats (56 kg N ha⁻¹). The dataset comprises of monthly values of subsurface drainage discharge, flow weighted nitrate concentrations, and the mass of nitrate-nitrogen (NO3-N) in drainage discharge for each of 30 corresponding experimental plots from 2014 to 2020. Dataset also includes annual harvested grain yields corrected to standard moisture content and above-ground biomass yields (excluding grain).Resources in this dataset:Resource Title: Field Operations.xlsx. Metadata information describing management practices and operations for each crop each year.Resource Title: NitrateLoad_SubsurfaceDrainage_FWNC.csv. This dataset provides monthly values of Nitrate-N load, subsurface drainage discharge, and flow weighted nitrate concentrations from 2014 to 2020.Resource Title Set: Yield_Alfalfa.csv, Yield_ConvCorn.csv, Yield_ConvSoybean.csv, Yield_Oat.csv, Yield_OrgCorn.csv, and Yield_OrgSoybean.csv. These datasets provide biomass and grain yields of conventional soybean and corn, organic soybean, corn, oats and alfalfa from 2014-2020.Resource Title: Precipitation.csv. Cumulative monthly precipitation for the study location, 2014-2020. Monthly values were calculated from daily values from the Iowa Environmental Mesonet (https://mesonet.agron.iastate.edu/request/coop/fe.phtml).<br>

有机农业旨在实现作物轮作多样化，并依托有机肥料源构建土壤肥力、改善土壤健康指标。本数据集评估了有机耕作对美国爱荷华州中部人工排水软土（Mollisols）水质的影响。该项为期7年的研究对比了三种种植体系下的地下暗管硝酸盐流失量与作物产量：(1) 常规玉米（*Zea mays* L.）-大豆（*Glycine max* L.）轮作体系；(2) 有机玉米-大豆-燕麦（*Avena sativa* L.）/苜蓿（*Medicago sativa* L.）-苜蓿轮作体系；(3) 有机多年生牧场体系。

氮肥施用方案为：常规玉米采用侧施尿素硝酸铵溶液，施氮量为168 kg N ha⁻¹；有机玉米与燕麦则于春季施用堆肥，施氮量分别为168 kg N ha⁻¹与56 kg N ha⁻¹。

本数据集涵盖2014至2020年间，30个对应试验田的地下暗管排水流量、流量加权硝酸盐浓度，以及排水中硝态氮（NO3-N）质量的月度监测值。此外还包含经标准含水率校正后的年度籽粒收获产量，以及地上生物量产量（不含籽粒）。

本数据集包含以下资源：
1. 《Field Operations.xlsx》：记录各年度各作物田间管理措施与作业的元数据文件。
2. 《NitrateLoad_SubsurfaceDrainage_FWNC.csv》：提供2014-2020年硝态氮负荷、地下暗管排水量与流量加权硝酸盐浓度的月度数据。
3. 数据集组：《Yield_Alfalfa.csv》、《Yield_ConvCorn.csv》、《Yield_ConvSoybean.csv》、《Yield_Oat.csv》、《Yield_OrgCorn.csv》与《Yield_OrgSoybean.csv》，涵盖2014-2020年常规大豆、常规玉米、有机大豆、有机玉米、燕麦与苜蓿的生物量与籽粒产量数据。
4. 《Precipitation.csv》：研究区域2014-2020年的月度累积降水量，月度数据由爱荷华环境气象网（https://mesonet.agron.iastate.edu/request/coop/fe.phtml）的日度数据计算得到。