Conservation Tillage Systems on Agricultural Land in the Conterminous United States, 1992: National Resource Inventory Conservation Practice 329

This data set represents the estimated percentage of the 1-km grid cell that is covered by or subject to the agricultural conservation practice (CP329 ), Conservation Tillage Systems (CTS) on agricultural land by county. Conservation Tillage Systems is described as "managing the amount, orientation and distribution of crop and other plant residues on the soil surface year-round, while growing crops in narrow slots, or tilled or residue free strips in soil previously untilled by full-width inversion implements." (U.S. Department of Agriculture, 1995) This data set was created with geographic information systems (GIS) and database management tools. The acres on which CTS's are applied were totaled at the county level in the tabular NRI database and then apportioned to a raster coverage of agricultural land within the county based on the Enhanced National Land Cover Dataset (NLCDe) 1-kilometer resolution land cover grids (Nakagaki, 2003). Federal land is not considered in this analysis because NRI does not record information on those lands.

本数据集以县域为统计单元，估算了农用土地范围内，被农业保护实践CP329（保护性耕作系统，Conservation Tillage Systems, CTS）覆盖或受其规范约束的1公里网格单元占比。
美国农业部（U.S. Department of Agriculture）于1995年将保护性耕作系统定义为：全年管控土壤表面作物及其他植物残体的数量、朝向与分布格局，同时采用窄槽种植作物，或在未经过全幅翻转耕作机具翻耕过的土壤中设置免耕或无残茬条带进行种植。
本数据集依托地理信息系统（geographic information systems, GIS）与数据库管理工具构建完成。首先在表格化的NRI数据库中汇总各县域内应用保护性耕作系统的土地面积，随后基于增强型国家土地覆盖数据集（Enhanced National Land Cover Dataset, NLCDe）的1公里分辨率土地覆盖栅格（Nakagaki, 2003），将上述汇总面积分摊至县域内农用土地的栅格覆盖范围中。
本次分析未纳入联邦土地范畴，原因在于NRI未记录此类土地的相关信息。