College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China.
International Institute for Earth System Science, Nanjing University, Nanjing, 210023, China.
Environ Pollut. 2020 Oct;265(Pt A):114862. doi: 10.1016/j.envpol.2020.114862. Epub 2020 May 27.
The losses of excessive reactive nitrogen (N) from agricultural production pose detrimental impacts on water, air and land. However, N budgets of agroecosystems are still poorly quantified, presenting a barrier to understand the N turnover in agriculture. Agricultural ammonia (NH) volatilization has been recognized as a crucial contribution to the pollution of fine particulate matters over China through reacting with acid gases. Building on these challenges, the first national-scale model analysis was constructed on the N budgets to gain an overall insight into the current status of N flows in Chinese dryland systems towards sustainable N management. Total inputs of soil N in Chinese dryland soils were estimated at 121 kg N ha in 2010, considering all pathways including N manure, fertilizer, atmospheric deposition and litter from crop residues. Atmospheric N deposition accounted for 25% of N fertilizer plus N manure in Chinese dryland soils, suggesting that N deposition could not be ignored when estimating total N inputs to Chinese dryland soils. The highest ratio of NH volatilization to total N outputs was found at 43 kg N ha (∼21%) in Northern China, followed by 41 kg N ha (∼20%) in Sichuan Basin and 25 kg N ha (∼26%) in Northeastern China. The modeling results indicated that, if a 20% decrease in N fertilizer plus N manure was achieved, it would lead to a 24% (7-49%) reduction in NH volatilization. Substantial reductions of NH volatilization would also be achieved by making an improvement in changing management practices (controlled release fertilizer and full irrigation). The results would give an overall insight into N budgets in Chinese dryland soils. The constructed N budgets assisted with understanding agricultural N flows and NH pollution, and evaluated the impacts of human activities on N cycle towards a precise way to regulate agricultural management.
农业生产中过量活性氮（N）的损失对水、空气和土地造成了有害影响。然而，农业生态系统的 N 预算仍然难以量化，这成为了解农业中 N 转化的障碍。农业氨（NH）挥发已被认为是通过与酸性气体反应而对中国细颗粒物污染的重要贡献。基于这些挑战，首次对 N 预算进行了全国范围内的模型分析，以全面了解中国旱地系统中 N 流的现状，从而实现可持续的 N 管理。考虑到包括 N 有机肥、肥料、大气沉降和作物残茬凋落物在内的所有途径，2010 年中国旱地土壤中土壤 N 的总输入量估计为 121kg N ha。大气 N 沉降占中国旱地土壤 N 肥料加 N 有机肥的 25%，这表明在估计中国旱地土壤总 N 输入时，不能忽视 N 沉降。在中国北方，NH 挥发与总 N 输出之比最高，为 43kg N ha（约 21%），其次是四川盆地，为 41kg N ha（约 20%），东北地区为 25kg N ha（约 26%）。模拟结果表明，如果减少 20%的 N 肥料加 N 有机肥，NH 挥发将减少 24%（7-49%）。通过改变管理实践（控释肥料和全灌溉）也可以实现 NH 挥发的大量减少。这些结果将全面了解中国旱地土壤的 N 预算。构建的 N 预算有助于了解农业 N 流动和 NH 污染，并评估人类活动对 N 循环的影响，以实现精确调控农业管理的目的。
