Department of Plant Biology and Ecology, The University of the Basque Country, Barrio Sarriena s/n, 48940, Leioa, Biscay, Spain.
NEIKER-Basque Institute for Agricultural Research and Development, Berreaga, 1, 48160, Derio, Biscay, Spain.
Sci Rep. 2019 Sep 25;9(1):13864. doi: 10.1038/s41598-019-50347-1.
Nitrogen budgets help explain the supply pattern of N from the soil to the crop. Through budgeting, an improvement of the N fertilization strategy can be achieved. The objective of the present study, which was carried out under humid Mediterranean climate conditions, was to assess the influence of N fertilization, temperature and soil humidity on soil N dynamics during a whole oilseed rape growing cycle. A field experiment was conducted with two treatments: without N (0 N) and with application of 180 kg N ha(180 N). Mineralization was calculated from N balances made throughout the growing cycle, all while taking into account measured N uptake by oilseed rape and N losses by leaching and NO emissions. Nitrogen net mineralization was negative after fertilization, reaching -6.73 kg N ha day but total net mineralization over the year was similar for the 0 N and 180 N treatments (21 and 8 kg N ha, respectively). Temperatures over 5 °C were sufficient for initiating the mineralization processes. In the summer, when the soil water content was below the wilting point, immobilization took place; however, there is a risk of N leaching if rainfall occurs thereafter, mainly in the 180 N treatment.
氮素收支有助于解释土壤向作物供应氮素的模式。通过预算，可以改进氮肥策略。本研究在湿润的地中海气候条件下进行，目的是评估氮肥、温度和土壤湿度对整个油菜生长周期土壤氮素动态的影响。进行了一项田间试验，设两个处理：不施氮（0N）和施氮 180kg·ha（180N）。通过整个生长周期的氮平衡计算矿化作用，同时考虑油菜的实测氮吸收量和淋失及 NO 排放损失的氮量。施肥后氮净矿化作用为负值，达到-6.73kg·N·ha·d，但全年氮总矿化作用在 0N 和 180N 处理间相似（分别为 21 和 8kg·N·ha）。5°C 以上的温度足以启动矿化作用。在夏季，当土壤含水量低于萎蔫点时，会发生固定作用；然而，如果随后发生降雨，特别是在 180N 处理中，存在氮淋失的风险。
