Datasets for “Half-century history of crop nitrogen use efficiency in the conterminous United States: Variations over time, space and crop types”

This document describes the datasets for “Half-century history of crop nitrogen use efficiency in the conterminous United States: Variations over time, space and crop types”. The datasets include county-level nitrogen use efficiency and N surplus of eight crop types,in the U.S. from 1970 to 2017. The datasets reproduce the results of the manuscript and can be used to explore other topics.<br>

本文件旨在说明对应学术论文《美国本土作物氮素利用效率半世纪研究：时间、空间与作物类型维度的变异规律》所配套的数据集。该数据集涵盖1970年至2017年美国本土8种作物类型的县级尺度氮素利用效率（nitrogen use efficiency）与氮素盈余（nitrogen surplus）数据。本数据集可复现该研究论文的核心结果，亦可用于探索其他相关科研主题。