Projecting future nitrogen inputs: are we making the right assumptions?
Projecting future nitrogen inputs: are we making the right assumptions?
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DOI：
10.1088/1748-9326/ac6619
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发表时间：
2021-08
影响因子：
6.7
通讯作者：
S. Vishwakarma;Xin Zhang;N. Mueller
中科院分区：
文献类型：
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作者：
S. Vishwakarma;Xin Zhang;N. Mueller
在过去的一个世纪里，全球活性氮 (N) 的使用有所增加，以满足不断增长的粮食和生物燃料需求，同时造成了巨大的环境影响。解决持续的氮管理挑战需要预测未来氮的使用途径。科学文献中的几项研究预测了在一切照旧的情况下未来作物生产的氮输入量。然而，目前尚不清楚在使用一致的数据集时，使用产量响应函数来表征给定水平的技术和管理实践 (TMP) 将如何改变预测。在这项研究中，为了预测到 2050 年的氮输入，我们开发并测试了三种方法，即“相同的氮利用效率（NUE）”、“相同的 TMP”和“提高 TMP”。我们发现，考虑产量响应函数收益递减（“相同 TMP”）的方法导致 N 投入为 268 Tg N yr−1，这比在考虑和不考虑作物组合变化的情况下将 NUE 保持在当前水平时分别高出 61 和 48 Tg N yr−1。如果 TMP 继续以过去 50 年的速度发展，预计的 N 投入将减少到 204 Tg N yr−1，该值仍比 2006 年基准年的投入高出 59 Tg N yr−1。总体而言，我们的结果表明，假设 NUE 恒定在预测 N 投入时可能过于乐观，在调查未来的 N 预算时需要仔细探索所有的预测假设。
Global use of reactive nitrogen (N) has increased over the past century to meet growing food and biofuel demand, while contributing to substantial environmental impacts. Addressing continued N management challenges requires anticipating pathways of future N use. Several studies in the scientific literature have projected future N inputs for crop production under a business-as-usual scenario. However, it remains unclear how using yield response functions to characterize a given level of technology and management practices (TMP) will alter the projections when using a consistent dataset. In this study, to project N inputs to 2050, we developed and tested three approaches, namely ‘Same nitrogen use efficiency (NUE)’, ‘Same TMP’, and ‘Improving TMP’. We found the approach that considers diminishing returns in yield response functions (‘Same TMP’) resulted in 268 Tg N yr−1 of N inputs, which was 61 and 48 Tg N yr−1 higher than when keeping NUE at the current level with and without considering changes in crop mix, respectively. If TMP continue to evolve at the pace of past five decades, projected N inputs reduce to 204 Tg N yr−1, a value that is still 59 Tg N yr−1 higher than the inputs in the baseline year 2006. Overall, our results suggest that assuming a constant NUE may be too optimistic in projecting N inputs, and the full range of projection assumptions need to be carefully explored when investigating future N budgets.