硫磺和双氰胺配施对尿素在滇池北岸菜地土壤中转化的影响研究

Influences of Elemental Sulfur and Dicyandiamide on Urea Transformation in a Vegetable Soil from the Northern Bankside of Dianchi Lake Region

采用恒温土壤培养实验的结果表明,尿素在滇池北岸蔬菜地土壤中转化速率非常快,培养3天尿素水解了90%左右。施用硫磺2周后,土壤pH从8.15下降到7.5左右,施S0对减少土壤氨挥发可能是有利的。DCD对尿素在土壤中水解具有显著抑制作用,但S0、DCD对尿素水解协同效应不明显,主要是由于该类型土壤中尿素水解和S0分解不同步,前者显著快于后者。为了发挥施S0在减少氮素流失效果,建议S0施用时间比尿素早2周左右。S0施用能显著延缓土壤铵态氮的硝化作用。因此,S0与DCD合理配合施用,对减少氮素向滇池水体迁移可能具有实践意义。

An experiment of soil incubation under control condition was conducted to investigate effect of element sulphur（S^0）and dicyandiamide（DCD） on urea transformation in a vegetable soil from the northern bankside of Dianchi Lake region.Results showed that urea had a fast hydrolysis in the tested soil,and about 90% of urea was decomposed within 3-weeks after urea was applied to soil.Soil pH decreased from 8.15 to 7.5 in two-weeks after soil was supplied S^0 therefore,supply of S^0 could reduce NH3 volatilization.Application of DCD had a significantly inhibition on urea hydrolysis,but the combined effect of S^0 and DCD on urea hydrolysis was not observed because urea hydrolysis was not synchronous with S^0 oxidation,the former was fast than the latter.So the S^0 would be used in two-weeks earlier than DCD did in order to obtain the best effect of S^0 on reducing nitrogen loss.Application of S^0 significantly reduced nitrification.The present results revealed that supply of S^0 combined DCD could have a practical significance on control nitrogen movement to Dianchi lake.