氮肥施用对石灰性土壤交换性钙含量的影响

摘要

为了揭示长期土壤化学物质投入量的不断增加给土壤造成的“亚健康”现象,更新石灰性土壤不会产生钙亏缺的传统理念,本试验研究了施用NH4Cl、( NH4 )2SO4、NH4NO3和尿素4种常用氮肥对石灰性土壤表层交换性钙含量的影响.结果表明:石灰性土壤经NH4Cl、1/2(NH4)2SO4、NH4NO3三种同体积不同浓度铵态氮溶液的淋洗后,土壤中的交换性钙含量均呈现不同程度的下降,其中等当量铵的( NH4 )2SO4溶液比NH4Cl和NH4NO3溶液影响相对较大,影响程度依次为:NH4NO3＜ NH4Cl＜ (NH4)2SO4；尿素施入土样培养7d期间,土壤交换性钙与时间呈显著负相关,7d之后,土壤交换性钙趋于平稳.研究结论:大量长期施用化学氮肥使石灰性土壤表层交换性钙含量逐渐降低,脱钙作用使得土壤钙饱和度可以下降到50％以下,使得土壤呈现“亚健康”状态.%To reveal "sub-healthy" phenomenon, which brought with continually increasing of chemicals using into soil, and to renew the traditional concept that calcareous soil would not appear the phenomenon of calcium lack, an ex periment was conducted to analyse the impact of NH4CI, (NH4)SO4, NH4NO3 and urea treatment on exchangeable calci um content of calcareous soil. The result indicated: soil exchangeable calcium content presented various degree of decline after calcareous soil was drip washed by same volume and different concentration NH4CI, (NH4)2SO4, NH4NO3 solu tions, and the impact of the same equivalent NE4+ ,(NH4)2SO4 solution on soil exchangeable calcium was relatively larger than that of NH,C1 solution and NH4NO3 solution, the degree of relation was: NH4NO3 < NH4CI < (NH4)2SO4; when urea was executed into soil sample to cultivate, the soil exchangeable calcium content assumed remarkable inverse correlation with time within 7 days, but it tended to be steady after that. The research conclusion: the massive and long-term chemistry nitrogenous fertilizer employment caused the exchangeable calcium content in surface layer calcareous soil to reduce gradually, there was weak-decalcification phenomenon, and all degree of calcium saturation dropped to 50% or less, and the soil presented "sub-healthy" condition.