保水剂对氮肥氨挥发和氮磷钾养分淋溶损失的影响

采用“静态吸收法”和“土柱淋溶法”室内模拟试验,研究了保水剂施入土壤后对尿素氨挥发以及对尿素、磷酸一铵、氯化钾养分淋溶损失的影响.结果表明,土壤中施入保水剂后,尿素氨挥发量显著降低,并随着保水剂用量的增加效果更加明显.氨挥发量的降低与土壤含水量、土壤脲酶活性和土壤pH有关.土壤含水量较高时,土壤脲酶活性和土壤pH较低,尿素氨挥发量也较少,土壤含水量为田间持水量的75%和100%时,施用0.05%～0.80%的保水剂,尿素累积氨挥发量分别较不施保水剂处理减少8.97%～47.65%和16.78%～72.40%.土壤中施入保水剂同样能减少氮、磷、钾养分的淋溶损失,对于氮、钾养分来说,随着保水剂用量的增加,养分淋失量显著减少,但对于磷素养分来说,养分淋失量并不随着保水剂用量的增加而减少.施用0.05%～0.20%的保水剂时,氮、磷、钾养分累积淋失量分别较较不施保水剂处理减少13.60%～39.62%、28.31%～16.96%和6.76%～24.55%.

Effects of Water Retaining Agent on Ammonia Volatilization and Nutrient Leaching Loss from N, P and K Fertdizers

Static adsorption and soil column leaching methods were used to study the effect of water retaining agent (WRA) in soils on ammonia volatilization from urea and nutrients leaching loss from urea, monoamonium phosphate and potassium chloride. The results showed that WRA strongly restrained ammonia volatilization. The amount of ammonia volatilization obviously decreased with the increase of WRA application level. The decrease of the amount of ammonia volatilization was closely related to soil water content, soil urease activity and pH value. When the soil water content was higher, the soil urease activity and pH value were lower, the amount of ammonia volatilization was fewer. When the soil water content were 75% and 100% of field water capacity with 0.05%~0.80% WRA applied, the total accumulated amount of ammonia volatilization decreased by 8.97%~47.65% and 16.78%~72.40% compared with that of the controls, respectively. Applying WRA into soils also could reduce leaching loss of N, P and K nutrients. For N and K nutrients, the leaching loss amount significantly decreased with the increase of WRA application level, but for P nutrient, it did not. When the application level ranged from 0.05% to 0.2%, the total accumulated amount of leaching loss of N, P and K decreased by 13.60%~39.62%, 28.31%~16.96% and 6.76%~24.55% compared with that of the controls, respectively.