不同施肥制度下褐土及其微团聚体内酸解性氮分布变化

Distribution Changes of Acid Hydrolysable N in Cinnamon Soil and Its Micro-aggregates Under the Different Fertilization Systems

通过8年定位试验,研究不同施肥制度下褐土及其微团聚体内酸解性氮变化规律,从各级微团聚体全氮和酸解性氮储量角度探讨不同施肥制度下土壤氮素肥力的变化实质。结果表明,不施肥处理主要是由于10～50μm粒级全氮和酸解性氮储量降低而造成土壤氮素肥力下降;单施常量NPK化肥处理有同样趋势;增量NPK化肥处理主要通过提高<10μm粒级全氮和酸解性氮储量使土壤全氮和酸解性氮含量不下降;有机肥(物)料配施常量NPK化肥处理则主要通过增加大粒级特别是10～50μm粒级全氮和酸解性氮储量、降低<10μm粒级酸不溶性氮储量而使土壤氮素肥力水平得到提高,猪厩肥效果好于玉米秸和麦秸直接还田。采用有机肥(物)料配施常量NPK化肥是改善土壤氮素肥力的有效措施。

Eight years location experiment was conducted in cinnamon soil in Hebei province to study the changes of acid hydrolysable N in soil and its micro-aggregates, and to study the changes of the soil nitrogen fertility under different fertilizer regimes from the view points of the storage of total N and acid hydrolysable N in various micro-aggregates. The results showed that no fertilization mainly decreased the storage of total N and acid hydrolysable N in 10-50μm micro-aggregates, and resulted in soil nitrogen fertility decreased. The same tendency showed with application of the constant NPK fertilizers. The increment NPK fertilizers mainly increased the storage of total N and acid hydrolysable N in 〈10μm in order to keep content of soil to- tal N and acid hydrolysable N balancing. Organic manure combined with constant NPK enhanced total N and acid hydrolysable N in bigger sizes, especially in 10-50μm micro-aggregates, and decreased the storage of nonhydrolysable N in 〈10μm micro-aggregates, and improved soil nitrogen fertility. The contributions to soil nitrogen fertility in treatment of pigpen fertilizer were better than that of wheat straws and corn straws treatment. Organic manure combined with constant NPK is the most effective way to improve soil fertility.