关键词: 尿素, 稻田, 氨挥发损失

Abstract: simple acid trap unit(Fig.1)was used to measure directly the ammonia volatilization losses from applied urea under farmer's wetland rice field conditions in Philippines.The deep-placed supergranules of urea gave the lowest ammonia losses.The incorporated prilled urea gave lower magnitude of ammonia volatilization losses in the wetland rice field without floodwater as compared to that with floodwater(Tab.1).From the urea topdressed at different stages of rice growth,the losses by ammonia volatilization,on average,ammounted to 11.9% of N apnlied(Tab.2). Total N(urea-NNH₄⁺ -N),pH and temperature in floodwater were simultaneously tested for 10 days after fertilization in the wetland rice field.It was found that the applied urea resulted in a elevated N level in the floodwater which declined to rapidly negligible level within 3-6 days(Fig.2).Rather strong alkaline reaction in floodwater(pH>8)was often recorded(Fig.3)indicating that there was really a significant potential for ammoniaonclick="SelectDisplayDiv('EnDivSummaryMoreSummary','EnDivSummaryMore');DisplaySpanDiv('EnDivSummaryHuanYuan')">...更多 volatili- zation in the wetland rice field,though the soil(pH 6.0)and the irrigation water(pH 6.5) both were slight acidic.