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在田间用~(15)N示踪技术和微气象学的质量平衡法研究了石灰性稻田土壤上化肥氮的损失。结果表明:(1)碳铵和尿素在有水层下混施作基肥,氮素总损失分别高达72%和63%;其中氨挥发达到39%和30%,分别占总损失的54%和48%;都远高于以往在中性水稻土区酸性土壤上测得的结果。(2)石灰性稻田土壤氨挥发量大,是造成其氮素总损失远高于酸性稻田土壤的根本原因。两种土壤上,氮肥的反硝化损失量(差减法)似没有明显的差异。(3)石灰性土壤上氨挥发量大的主要原因是其高的土壤和灌溉水的pH。石灰性土壤的高pH和光照充足,促进了田面水中藻类的生长。由此引起的日间田面水pH的上升促进了尿素的氨挥发,而对碳铵的氨挥发的促进则不大。
In the field, the loss of fertilizer nitrogen in calcareous paddy soil was studied by ~ (15) N tracing technique and the micrometeorological mass balance method. The results showed that: (1) ammonium bicarbonate and urea were applied as basal fertilizer under the aquifer, the total loss of nitrogen was as high as 72% and 63%, respectively; ammonia volatilization reached 39% and 30%, accounting for 54% 48%; are far higher than in the past in the neutral paddy soil acidic soil measured results. (2) Ammonia volatilization in calcareous paddy soils is the root cause of total nitrogen loss far higher than that in acid paddy soils. There was no significant difference in the amount of denitrification loss (difference subtraction method) of nitrogenous fertilizer on the two soils. (3) The main reason for the large amount of ammonia volatilization in calcareous soil is the pH of its high soil and irrigation water. The high pH and light of calcareous soil are sufficient to promote the growth of algae in surface water. The resulting rise in daytime surface water pH promotes ammonia volatilization of urea while a slight contribution to ammonia volatilization of ammonium bicarbonate.