Nitrogen transformation processes in relation to improved cultural practices for lowland rice
Nitrogen transformation processes in relation to improved cultural practices for lowland rice
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DOI：
10.1007/bf02370932
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发表时间：
1987-02
期刊：
影响因子：
4.9
通讯作者：
S. Datta
中科院分区：
文献类型：
--
作者：
S. Datta
不适当的施氮方法和时机会导致50-60%的氮素损失。近年来的氮素转化研究表明，低地水稻土中的NH3挥发是一种重要的损失机制，在田间条件下造成5-47%的肥料损失。估计反硝化损失在28%至33%之间。低地水稻的氨挥发损失可以通过以下方式控制：i）在还原层中放置肥料并适时施用，ii）使用苯基磷酰二胺（PPD）来延缓淹水土壤中的脲酶活性，iii）使用杀藻剂来帮助稳定洪水pH值的变化。硝化抑制剂作为另一种方法的有效性仍在评估中。作物吸收的氮中有60-80%来自天然氮库，利用土地上已有的资源，低地水稻的大幅增产是很有可能的。对土壤氮素及其管理的深入研究，以及对土壤氮素动态的了解，将大大有助于减少土壤中的固定和铵固定，提高水稻作物对氮素的有效性。关键的研究需求包括更加重视灌溉低地水稻的氮转化过程，因为灌溉低地低地水稻生长在比灌溉低地水稻更恶劣和多变的环境条件下。
Inappropriate method and timing of N fertilizer application was found to result in 50–60% N losses. Recent nitrogen transformation studies indicate that NH3volatilization in lowland rice soils is an important loss mechanism, causing a 5–47% loss of applied fertilizer under field conditions. Estimated denitrification losses were between 28 and 33%. Ammonia volatilization losses from lowland rice can be controlled by i) placement of fertilizer in the reduced layer and proper timing of application, ii) using phenylphosphorodiamidate (PPD) to delay urease activity in flooded soils, and iii) using algicides to help stabilize changes in floodwater pH.Appropriate fertilizer placement and timing is probably the most effective technique in controlling denitrification at the farm level. The effectivity of nitrification inhibitors as another method is still being evaluated.With 60–80% of N absorbed by the crop derived from the native N pool, substantial yield gains in lowland rice are highly possible with resources already in the land. Extensive studies on soil N and its management, and an understanding of soil N dynamics will greatly facilitate the decrease in immobilization and ammonium fixation in the soil and the increase in N availability to the rice crop. Critical research needs include greater emphasis on N transformation processes in rainfed lowland rice which is grown under more harsh and variable environmental regimes than irrigated lowland rice.