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本文总结了NH_3从表施的氮肥尤其是尿素中挥发损失方面的研究文献。实验室、温室测定NH_3挥发,设计可复杂,条件可控制,便于了解基本化学过程及阐明各种参数。其中动态封闭系统最接近田间实际情况。NH_3挥发量也可在田间通过植物生长总量、氮吸收量及施氮量之间的函数关系求之。但田间试验费用高,且因素多变,故影响对基本参数的充分了解。NH_3从尿素挥发包括微生物转化及化学反应,受土壤粘粒、硝化作用以及与尿素水解终产物(NH_4)_2CO_3伴生的钙化物的溶解度等因素影响。酸、尿酶抑制剂(包括重金属、有机物等)可抑制挥发,但目前实用有困难。影响NH_3挥发的因素还有氮肥种类、施用量、施用部位、方法、温度、土壤代换量、水分、土壤有机质含量、尿酶活性、土壤pH等。适当选用添加剂如K、Ca、Mg的氯化物和硝酸盐以及将氮肥施入表层以下几毫米可减少或消除NH_3挥发。
This paper summarizes the research literature on the NH_3 volatilization loss from surface nitrogen fertilizers, especially urea. Laboratory, greenhouse determination NH_3 volatilization, the design can be complex, conditions can be controlled, easy to understand the basic chemical processes and clarify various parameters. The dynamic closed system closest to the actual situation in the field. NH_3 volatilization can also be calculated in the field as a function of the total amount of plant growth, nitrogen uptake and nitrogen application rate. However, high cost of field trials, and changing factors, it affects the full understanding of the basic parameters. NH_3 volatilization from urea, including microbial transformation and chemical reaction, is affected by factors such as soil clay, nitrification and the solubility of calcification associated with the final hydrolyzate of urea (NH_4) _2CO_3. Acid, urease inhibitors (including heavy metals, organic matter, etc.) can inhibit the volatility, but practical difficulties. Affect the NH_3 volatile factors include nitrogen fertilizer type, application rate, application site, method, temperature, soil substitution, moisture, soil organic matter content, urinary enzyme activity, soil pH and so on. Appropriate use of additives such as K, Ca, Mg chloride and nitrate and nitrogen fertilizer applied to the surface a few millimeters can reduce or eliminate NH3 volatilization.