Data from: Crop Sequence and Nitrogen Fertilization Effects on Soil Properties in the Western Corn Belt

Understanding long-term management effects on soil properties is necessary to determine the sustainability of cropping systems. Documentation of soil property responses to corn-based cropping systems in the Western Corn Belt, however, is limited. A study was conducted near Mead, Nebraska to document the effects of four crop sequences (continuous corn, corn-soybean, corn-oat+clover-grain sorghum-soybean, corn-soybean-grain sorghum-oat+clover) and three nitrogen (N) rates (zero, low, high) on a suite of soil properties. At the time of sampling (spring 1999), treatments had been in place for 16 years. Soil samples were collected from two depths using a 1.8 cm step-down probe: 0-7.6 cm and 0-30.5 cm. Soil pH and electrical conductivity was estimated from a 1:1 soil-water mixture. Soil nitrate-N was measured using 1:10 soil-KCl extracts and the cadmium reduction method. Extractable P was determined by the Bray P-1 method. Particulate organic matter was determined by weight loss-on-ignition. Total carbon and N were determined by dry combustion. Potentially mineralizable N was determined by anerobic incubation, while microbial biomass was estimated by microwave irradiation. Soils data were used to identify associations with 16-year averages of grain and stover yield, grain and stover N uptake, and post-harvest soil nitrate-N. Data may be used to understand soil responses to corn-based cropping systems under rainfed conditions in a humid continental climate. Applicable USDA soil types include Yutan, Tomek, and Fillmore.

明晰长期管理措施对土壤性状的影响，是判定种植系统可持续性的必要前提。然而，目前针对美国西部玉米带内玉米主导型种植系统下土壤性状响应的相关记载仍较为匮乏。本研究于内布拉斯加州米德（Mead）附近开展，旨在明确4种轮作序列（连作玉米、玉米-大豆轮作、玉米-燕麦+三叶草-粒用高粱-大豆轮作、玉米-大豆-粒用高粱-燕麦+三叶草轮作）与3个氮肥（nitrogen, N）施用量梯度（零施用量、低施用量、高施用量）对一系列土壤性状的影响。于1999年春季采样时，各试验处理已连续实施16年。采用直径1.8 cm的分层采样探针采集两个土层的土壤样品：0~7.6 cm与0~30.5 cm。通过1:1土水比悬浮液测定土壤pH值与电导率（electrical conductivity, EC）。以1:10土-氯化钾（KCl）浸提液结合镉还原法测定土壤硝态氮（nitrate-N）含量。有效磷（extractable P）采用Bray P-1法测定。颗粒有机质通过灼烧减重法定量。总碳与总氮采用干式燃烧法测定。潜在矿化氮采用厌氧培养法测定，而微生物生物量则通过微波辐照法估算。本数据集的土壤数据可用于解析16年平均籽粒产量、秸秆产量、籽粒吸氮量、秸秆吸氮量以及收获后土壤硝态氮含量之间的关联。该数据集可用于探究湿润大陆性气候区雨养条件下玉米主导型种植系统的土壤响应特征。适用的美国农业部（United States Department of Agriculture, USDA）土壤类型包括Yutan、Tomek与Fillmore。