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利用超声波分散—沉降法对利用15N标记的硫铵、稻草和猪粪培养处理一年后的土壤进行物理分级,研究了施入土壤的肥料N在土壤不同粒级中的分布,并利用黑麦草研究了土壤不同粒级中15N的有效性。结果表明,施用稻草和猪粪提高了0～2μm粒级和2～10μm粒级在土壤中的分配比例。硫铵15N、稻草15N和猪粪15N在土壤0～2μm粒级中的分布比例都在14%左右,在2～10μm和10～50μm粒级中的分布比例分别为22%和14%左右。但在>100μm(残渣)粒级中来自硫铵的15N比例为16%左右,而来自稻草和猪粪的15N比例则在30%以上。施用硫铵土壤的2～10μm粒级中,黑麦草对15N的利用率最高,50～100μm粒级中的15N利用率最低。而施用稻草和猪粪土壤的粒级中15N利用率以10～50μm粒级中最高。表明不同性质的肥料在土壤中的不同转化方向影响了肥料N在土壤不同粒级中的分布。由于不同粒级的土壤颗粒对有机物质的吸持力不同,从而决定了在不同粒级中N的生物有效性。
The soil of 15N labeled ammonium sulfate, straw and pig manure was treated by ultrasonic dispersion-sedimentation method for one year. The distribution of fertilizer N applied to soil in different grain fractions of soil was studied. The effects of ryegrass The effectiveness of 15N in different soil fractions was studied. The results showed that the application of straw and pig manure increased the distribution ratio of 0 ~ 2μm grain size and 2 ~ 10μm grain size in soil. The proportions of ammonium sulfate 15N, straw 15N and pig manure 15N were all around 14% in 0 ~ 2μm soil fractions, and 22% and 14% in 2 ~ 10μm and 10 ~ 50μm fractions, respectively. However, in the> 100 μm (residue) fraction, the 15N ratio derived from ammonium sulfate was about 16%, while the 15N fraction derived from straw and pig manure was 30% or more. Among 2 ~ 10μm fractions of ammonium sulphate soil, ryegrass had the highest utilization rate of 15N and the lowest utilization rate of 15N among 50 ~ 100μm fractions. However, the 15N utilization in the grain fractions of straw and pig manure was the highest in the grain fractions of 10-50 μm. It shows that the different transformation directions of fertilizers with different properties in soil affect the distribution of fertilizer N in different soil fractions. The bioavailability of N in different fractions is determined by the different holding forces of soil particles on different organic fractions.