稻田土壤对铵的矿物固定对土壤保氮作用的贡献

为了定量评价土壤对铵的矿物固定作用在土壤对肥料氮的保持作用中的相对贡献,通过室内培养试验和分析测定,研究了湖南省几种主要母质发育的水稻土对添加铵的矿物固定作用及其对土壤保氮作用的贡献。结果表明:土壤对外源铵的矿物固定是土壤重要的保氮机制之一,但不同土壤对保氮作用的相对贡献大小不一,以河沙泥的固铵作用对土壤保氮作用的贡献最大,固铵量占总保氮量的51.5%,红黄泥最低,固铵量仅占总保氮量的17.1%,其余五种土壤的固铵作用对土壤保氮作用的贡献大小顺序依次是黄泥田(43.7%)、湖潮泥(35.5%)、紫泥田(35.4%)、灰泥田(25.0%)、麻沙泥(20.8%)。

Mineral fixation of ammonium by paddy soils in relation to the N-preserving capacity in paddy soils

The fixation capacity for added ammonium and its contribution to the N-preserving capacity of the paddy soils derived from chief parent materials in Hunan province,China,were studied with laboratory incubation and determination to evaluate the importance of fixation for added ammonium in the soils to the nutrient supplying and stabling properties.The results showed that the fixation for added ammonium by the soils was one of the important N-preserving mechanisms.But its contribution to the N-pre-serving in soils varied with soil types.Fixation for added ammonium by alluvial sandy soil had the greatest importance of the N-preserving in the soil,and accounted for 51.5% of the total N-preserving capacity.Fixation for added ammonium by reddish yellow clayey soil had the lowest,and only accounted for 17.1%.The order of other five soils in magnitude was yellow clayey soil(43.7%),newly laky clayey soil(35.5%),purple clayey soil(35.4%),gray clayey soil(25.0%),and granitic sandy soil(20.8%),respectively.