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关于氮肥中氨的挥发作用研究,已经进行了许多室内试验,但在田间条件下进行试验的很少。这项试验目的是评价在石灰性土壤上表施硫铵及硝铵后田间的氨挥发作用,用Houston黑粘土,属细质,蒙脱土型,udic pellusterts热带土科,挥发作用是通过测定沿海狗牙根对氮的吸收间接估算的,也直接测定氨的挥发。在田间小区研究中,施用硝铵的氮,估计其损失范围是3—10％,施用颗粒硫铵的损失范围为36—45％,施用140及280公斤氮/公顷液体硫铵的损失为25—55％。从颗粒硫铵直接测定氨的损失,1975年夏季施用的为施氮量的47,43,59,50％,1976年春季施用的为施氮量的39,30,27,35％,施肥量是33,66,140,280公斤氮/公顷。在春季,氨的损失较少,显然是由于当时土壤温度较低。在两个时期内所发生氨损失的日变动是一致的,这些变动与大气相对湿度的日变动密切符合。这些结果与先前试验室研究的结果是一致的,即在石灰性粘质土壤上表施的硫铵要比硝铵损失大得多。
There have been many laboratory tests on ammonia volatilization in nitrogen fertilizers, but few have been conducted under field conditions. The purpose of this experiment was to evaluate ammonia volatilization in the calcareous soil after application of ammonium sulphate and ammonium sulphate. Houston black clay was a fine, montmorillonite-type, udic pellusterts tropical soil with the volatility determined by measurement Indirect estimation of nitrogen uptake by coastal bermudagrass also directly measures ammonia volatilization. In field plot studies, ammonium nitrate was estimated to have a loss range of 3-10% using ammonium nitrate, a loss range of 36-45% with granular ammonium sulfate and a loss of 25 with ammonium sulfate applied at 140 and 280 kg nitrogen / ha -55%. Direct determination of ammonia losses from particulate ammonium sulfate was applied at 47, 43, 59, 50% of the nitrogen application rate in the summer of 1975, 39, 30, 27, 35% of the nitrogen application rate in the spring of 1976, Is 33,66,140,280 kg nitrogen / ha. In the spring, there was less ammonia loss, apparently due to the lower soil temperature at that time. The diurnal variations in ammonia losses occurring over the two periods are consistent, and these changes closely correspond to the diurnal variations in atmospheric relative humidity. These results are in agreement with the results of previous laboratory studies that the ammonium sulfate applied to calcareous soils is far less lossy than ammonium nitrate.