Reactive nitrogen losses from Canadian agricultural soils over 36 years

文献类型： 外文期刊

第一作者： Yang, J. Y.

作者： Yang, J. Y.;Drury, C. F.;Jiang, R.;Jiang, R.;Worth, D. E.;Grant, B. B.;Smith, W. N.;Bittman, S.

作者机构：

关键词： Reactive nitrogen; Nitrous oxide emission; Ammonia emission; Nitrate leaching; Surplus nitrogen

期刊名称：ECOLOGICAL MODELLING （ 影响因子：2.6； 五年影响因子：2.9 ）

ISSN： 0304-3800

年卷期： 2024 年 495 卷

页码：

收录情况： SCI

摘要： Agriculture is a major source of reactive nitrogen (Nr) losses through ammonia (NH3) volatilization, nitrous oxide (N2O) emissions and nitrate (NO3-) leaching. A Canadian Agricultural Nitrogen Budget for Reactive N (CANBNr) model was developed to estimate the nitrogen (N) balance in soils, including N removals by harvested crops and Nr losses for the years 1981-2016 across Canada. Annual N inputs to farmland include commercial fertilizer N, livestock manure N, symbiotic and asymbiotic biological N fixation and atmospheric N deposition of NOx and NH3. The total annual N input for Canadian farmland was 5528 Gg N (103.2 kg N ha(-1)) in 2016 where N removal by crops and Nr accounted for 72.5 % (74.9 kg N ha(-1)) and 13.4 % (13.9 kg N ha(-1)), respectively. The Nr losses from N2O emissions, NH3 volatilization and NO3- leaching accounted for 64 Gg N (1.2 kg N ha(-1)), 330 Gg N (6.2 kg N ha(-1)) and 348 Gg N (6.5 kg N ha(-1)), which represents between 1.2-6.3 % of total N input. A total of 777 Gg N (14.5 kg N ha(-1)) remained in the soil as surplus N (14.1 % of total N input), which could be available to subsequent crops in dryer regions but might be subject to N2O loss through nitrification or denitrification processes or NO3- leaching following heavy rains in humid regions. Nitrous oxide and ammonia emissions increased over a 36-year period due to increased fertilizer N inputs. The percentage of N inputs that was estimated to be lost as Nr increased from 17.9 % in 1981 to the peak level of 19.8 % in 2001 and then declined to 13.4 % in 2016. Total N removal by crops increased at a greater rate than N input during the 2001-2016 period resulting in an increased N uptake by crops over the last 15 years. The improved management of fertilizer N for agricultural systems represents a key opportunity for both farmers and policy makers to further reduce Nr losses from Canadian farmland without negatively impacting productivity.

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