近日，南京农业大学刘树伟和邹建文合作，探究了减少全球玉米和小麦生产中化肥使用造成的土壤氮流失。这一研究成果发表在2024年9月17日出版的国际学术期刊《自然—地球科学》上。
据介绍，玉米和小麦是两种主要的主食，它们共同贡献了世界粮食供应的三分之二。在这两种作物的种植过程中，氮肥的广泛使用导致活性氮(Nr)大量流失到环境中。
利用机器学习算法，研究人员根据全球实地测量结果生成了农作物特定土壤N损失的高分辨率地图。结果预估，到2020年，全球每年因使用合成氮肥(包括氮氧化物(N2O)、一氧化氮(NO)、氨(NH3)、氮淋失和径流直接排放的土壤硝态氮损失，分别为玉米18、162、9、147和110万吨，小麦分别为12、133、7、121和95万吨。
据估计，玉米和小麦因合成氮肥导致的土壤硝态氮年间接排放分别为4.5万吨和3.7万吨，其中水文途径起主导作用。在低于该值的地区，将氮利用效率提高至60%，可实现这两种作物每年减少400万吨土壤Nr损失的总潜力，从而将N2O间接排放减少49%。该研究结果有助于限制农业中化肥使用的全球氮预算，从而有助于使用建模方法改进氮循环-气候反馈预测。
附：英文原文
Title: Reducing soil nitrogen losses from fertilizer use in global maize and wheat production
Author: Wang, Chao, Shen, Yun, Fang, Xiantao, Xiao, Shuqi, Liu, Genyuan, Wang, Ligang, Gu, Baojing, Zhou, Feng, Chen, Deli, Tian, Hanqin, Ciais, Philippe, Zou, Jianwen, Liu, Shuwei
Issue&Volume: 2024-09-17
Abstract: Maize and wheat are two major staple foods that collectively contribute two-thirds of the world’s grain supply. The extensive use of nitrogen (N) fertilizers during the cultivation of both crops leads to significant losses of reactive nitrogen (Nr) into the environment. Here, using machine learning algorithms, we generate high-resolution maps of crop-specific soil Nr losses based on global field measurements. We estimate that global annual soil Nr losses from the use of synthetic N fertilizer in 2020, including direct emissions of nitrous oxide (N2O), nitric oxide (NO), ammonia (NH3), N leaching and run-off, amount to 0.18, 1.62, 0.09, 1.47 and 1.10 million tonnes N for maize, and 0.12, 1.33, 0.07, 1.21 and 0.95 million tonnes N for wheat, respectively. The annual indirect N2O emissions induced by synthetic N fertilizer use from these soil Nr losses are estimated to be 45,000 and 37,000 tonnes for maize and wheat, respectively, with hydrologic pathways playing a predominant role. Enhancing N use efficiency up to 60% for regions below this value can achieve a total soil Nr loss mitigation potential of 4.00 million tonnes per year for the two crops, thereby reducing indirect N2O emissions by 49%. Our results contribute to constrain global N budgets from the use of fertilizer in agriculture, which then can help to improve projections of nitrogen cycle–climate feedbacks using modelling approaches.
DOI: 10.1038/s41561-024-01542-x
Source: https://www.nature.com/articles/s41561-024-01542-x