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Modelled Quantification of Different Sources of Nitrogen Inefficiency in Semi-Arid Cropping Systems
Agronomy ( IF 3.949 ) Pub Date : 2021-06-16 , DOI: 10.3390/agronomy11061222
Niloufar Nasrollahi , James Hunt , Caixian Tang , David Cann

Most dryland grain growers in Australia retain all or most of their crop residues to protect the soil from erosion and to improve water conservation but retaining stubbles with a high carbon-to-nitrogen (C:N) ratio can affect N availability to crops. A simulation experiment was conducted to investigate the effects of N fertilizer application rate and residue retention on soil N dynamics. The simulation used seven N fertilizer application rates (0, 25, 50, 75, 100, 150 and 200 kg N ha−1) to wheat (Triticum aestivum) over 27 years (1990–2016) at four locations across a gradient in annual rainfall in Victoria, Australia. Nitrogen immobilization, denitrification and N leaching loss were predicted and collectively defined as sources of N inefficiency. When residues were retained, immobilization was predicted to be the biggest source of inefficiency at all simulated sites at N application rates currently used by growers. Leaching became a bigger source of inefficiency at one site with low soil water-holding capacity, but only at N rates much higher than would currently be commercially applied, resulting in high levels of nitrate (NO3) accumulating in the soil. Denitrification was an appreciable source of inefficiency at higher rainfall sites. Further research is necessary to evaluate strategies to minimize immobilization of N in semi-arid cropping systems.

中文翻译:

半干旱作物系统中氮效率低下的不同来源的模拟量化

澳大利亚的大多数旱地粮食种植者保留全部或大部分作物残留物,以保护土壤免受侵蚀并改善水资源保护,但保留碳氮 (C:N) 比高的残茬会影响作物的氮可用性。通过模拟试验研究了施氮量和残留量对土壤氮动态的影响。该模拟使用了 7 种氮肥施用量(0、25、50、75、100、150 和 200 kg N ha -1)对小麦(Triticum aestivum) 超过 27 年(1990-2016)在澳大利亚维多利亚年降雨量梯度的四个地点。氮固定、反硝化和 N 浸出损失被预测并共同定义为 N 效率低下的来源。当残留物被保留时,在种植者目前使用的施氮量下,在所有模拟地点,固定化被预测为效率低下的最大来源。在一个土壤持水能力低的地点,浸出成为导致效率低下的一个更大的根源,但只是在比目前商业应用的氮率高得多的情况下,导致高水平的硝酸盐(NO 3 -) 在土壤中积累。在降雨量较大的地点,反硝化作用是效率低下的一个明显原因。需要进一步研究以评估在半干旱种植系统中最大限度地减少氮固定的策略。
更新日期:2021-06-16
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