施肥对巢湖流域稻季氨挥发损失的影响

Effect of fertilization on ammonia volatilization from paddy fields in Chao Lake Basin

采用通气法对巢湖流域稻季土壤氨挥发原位监测,研究了不同施肥量及秸秆还田处理对稻季氨挥发的影响。结果表明,氨挥发峰值发生在施肥后的第1—3天,氨挥发损失主要集中于施肥后的1周。2010年整个稻季氨挥发净损失量为7.22—14.20 kg/hm2,占氮肥施用量的4.59%—6.64%,基肥期是主要的氨挥发时期,约占总氨挥发量的60%,穗肥期氨挥发总损失量最小。常规施肥处理氨挥发总损失量最大,与常规施肥相比,优化施肥、减量化施肥均能减少稻田土壤氨挥发损失1%—2%,氮磷肥减量同时秸秆还田处理氨挥发量最小,其总氨挥发量占常规处理的54%。施肥后的1—2d内田面水中的NH+4-N浓度达到最大值,且各施肥处理的氨挥发量与同期田面水中的NH+4-N浓度呈线性正相关。结合经济效益和环境效应分析发现,秸秆还田处理可减少氨挥发损失,同时获得较高的经济效益,适宜在巢湖流域水稻季推广。

Ammonia（NH3） is formed constantly in soils because of the biological degradation of organic compounds and NH＋4 yielding mineral and organic fertilizers.NH3 volatilization is one of the major losses of applied nitrogen fertilizers,which is affected by the local climate conditions（e.g.,temperature,sun illumination,and wind speed）,soil moisture content,urease activity,fertilization time,and ammonium concentration in surface water of the paddy fields.In this study,A situ experiment combined with venting method was conducted to study the effects of different fertilization patterns on NH3 volatilization in Chao Lake Basin during the rice season in 2010.In the experiment,there were six treatments with the control,the conventional fertilization,the optimization fertilization（according to local test of fertilization recipe）,the reduction by 30% of nitrogen fertilizer,the reduction by 50% of phosphorus fertilizer and the straw return.The results showed that the NH3 volatilization loss from paddy fields was affected by fertilization and ammonium nitrogen（NH＋4-N）concentration in surface water of the paddy fields.The NH3 volatilization among different treatments lasted for one week and the volatilization peak occurred within one to three days after fertilization,then declined quickly.When the rate of phosphorus fertilizer remained the same（e.g.,he treatments of the optimization fertilization and the reduction by 30% of nitrogen fertilizer）,The concentration of NH3 volatilization loss enhanced as the nitrogen application rate increased with the same rate of phosphorus fertilizer.The amount of NH3 volatilization ranged from 7.22 to 14.20 kg/hm2,Which accounted for 4.59% to 6.64% of the total applied N for the whole period of rice growth.Compared with the conventional fertilization,the NH3 volatilization loss was reduced by 1% to 2% respectively with the treatments of the reduction by 30% of nitrogen fertilizer、by 50% of phosphorus fertilizer and the optimization fertilization,while the NH3 volatilization loss was reduced by 6.98 kg/hm2 with the treatment of the straw return,which total ammonia volatilize quantity was 54% of the conventional fertilization.The highest NH3 volatilization loss occurred at basal dressing,which amount for 60% of the total NH3 loss,while the lowest loss did at panicle stage.The concentration of NH＋4-N in surface water reached the highest within one to two days after fertilization.The positive correlation was observed between NH3 loss and NH＋4-N concentration in the surface water of the basal dressing and the first top-dressing.From the point of the water improvement of Chao Lake basin,the period within a week after the fertilizer application was a critical time to control N loss and leaching from flooded paddy fields.NH3 loss would be decreased when N and P ferlization was rational.It is necessary to apply rational and balanced fertilization for N and P.Combined with economic benefit and environmental risk,the straw return is recommended for rice production in Chao Lake basin.