石灰性稻田土壤上化肥氮损失的研究

INVESTIGATIONS ON NITROGEN LOSSES FROM FERTILIZERS APPLIED TO FLOODED CALCAREOUS PADDY SOIL

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。

N losses were investigated in the field of calcareous paddy soil by ^(?)N-tracer and micrometeorological mass balance techniques. Results revealed that: 1. Total N loss from ammonium bicarbonate and urea broadcast into floodwater and incorporated just before transplanting was 72% and 63%, of which 39% and 30% was of ammonia loss which accounted for 54% and 48% of total N loss, respectively. 2. The higher N loss from calcareous soil, as compared with acidic one, is primarily due to the higher ammonia loss, because the difference in denitrification loss between the two soils investigated in this series of research was insignificant. 3. The higher ammonia loss from ammonium bicarbonate applied to calcareous soil can be mainly attributed to the high pH Values of the soil and irrigation water. However, the elevation of floodwater pH in day time resulted from the vigorous growth of algae also contribute partly the higher ammonia loss from urea applied to the calcareous soil.