施用不同种类氮肥对日光温室土壤溶液离子组成的影响

采用土培模拟试验研究了施用不同量的尿素CO(NH2)2]、碳酸氢铵（NH4HCO3）、硫酸铵(NH4)2SO4]对培养期间日光温室土壤溶液电导率（EC）和不同离子组成及比例的影响。结果表明，不同氮肥种类对土壤溶液电导率（EC）的影响主要表现在培养的前一周左右，之后不同品种间无明显差异。土壤溶液中NO3--N含量随施氮量和培养时间呈明显的上升趋势，不同氮肥种类NO3--N含量无明显差异；不同氮肥种类处理土壤溶液中NH4+-N含量在培养的前7 d有所差异，之后亦无差异。随着氮肥施用量的增加，日光温室土壤溶液的EC及K+、Na+、Ca2+、Mg2+离子的浓度升高；增施氮肥同时提高了土壤溶液中Ca/K、Mg/K的比值，而对土壤溶液钾的活度比（ARK）无显著影响。说明氮肥施用量是影响土－液界面离子交换的重要因素；由此带来的日光温室土壤盐分累积以及K+、Na+、Ca2+和Mg2+离子的淋失等问题值得关注。

Effects of the application of different nitrogen fertilizers on the ion compositions in solution of the greenhouse soil

An incubation experimental method was used to study the effects of application of different types of nitrogen fertilizers CO (NH₂)₂, NH₄HCO₃, and (NH₄)₂SO₄] on the electrical conductivity (EC) and ion compositions and ratios in solution of a greenhouse soil. The addition of different types of nitrogen fertilizers only influenced EC of soil solution in the first week of incubation, after that the differences were not significant. The EC of soil solution was significantly increased by N application, indicating the significant contribution of nitrogen application to the accumulation of salts in the soil. The nitrate concentration in soil solution was increased with the application of N fertilizer and the incubation time. There were not significant differences in the nitrate concentrations in soil solution of different N fertilizer treatments. Different N fertilizer types only had some effects on NH₄⁺-N concentration in soil solution in the first week of incubation, and then the differences among the different types of N fertilizers were not significant. The application of N fertilizer also increased the concentrations of K⁺, Na⁺, Ca²⁺and Mg²⁺ in soil solution, especially the concentration of Ca²⁺and Mg²⁺ ions; it was also the situation for the ratios of Ca/K and Mg/K in soil solution; however, the K⁺ activity ratio in solution remained constant during the incubation. It is concluded that the N application rates have significant effect on the ion balances between soil and solution interface. More attention needs to be paid to the effects of N application rates on the accumulation of salts in soil, and the leaching of K⁺, Na⁺, Ca²⁺ and Mg²⁺ from soil solution.