长期施肥对红壤性水稻土氮素形态的影响

采用28年的长期田间定位试验,研究了长期不同施肥处理对红壤性水稻土氮素形态的影响。结果表明,在不施肥（CK）、无机肥（NPK）、有机肥（猪粪＋紫云英绿肥,M）和无机肥与有机肥配施（NPKM）处理中,土壤全氮、碱解氮、铵态氮、硝态氮和微生物氮含量均随土层深度的增加而降低;不同施肥处理土壤全氮、碱解氮、铵态氮、硝态氮和微生物氮含量从高到低顺序均为：NPKM〉M〉NPK〉CK,长期施用肥料,特别是有机肥与无机肥配施能提高全氮、碱解氮、铵态氮、硝态氮和微生物氮含量,即促进了土壤氮库的积累;且不同施肥处理A、P层碱解氮、铵态氮、硝态氮、微生物氮含量和土壤全氮含量之间呈极显著正相关关系。因此,无机肥配施有机肥可使土壤氮素各形态含量均显著提高,是提高土壤氮素肥力的根本途径。

Effects of Long-term Different Fertilizations on Nitrogen in Red Paddy Soil

A long-term field experiment was set in Jinxian county,institute of red soil in Jiangxi Province(116°20′24″ E,28°15′30″ N).One of the aims of the experiment was to study effects of long-term different fertilizations on nitrogen in red paddy soil.Treatments were:(1) Zero fertilization(CK),(2) chemical fertilizers alone(NPK),(3) organic fertilizers alone(M) and(4) a combination of chemical and organic fertilizers(NPKM).Results showed contents of total nitrogen,available nitrogen,ammonium nitrogen,nitrate nitrogen,microbial biomass nitrogen in red paddy soil decreased with the increasing of soil depth.Contents of total nitrogen,available nitrogen,ammonium nitrogen,nitrate nitrogen,microbial biomass nitrogen at same horizon in different fertilizations decreased in the sequence of NPKM>M>NPK>CK.Long-term application of organic fertilizer or combination of organic and inorganic fertilizer promotes increasing of total nitrogen,available nitrogen,ammonium nitrogen,nitrate nitrogen,microbial biomass nitrogen in red paddy soil.It is obvious that NPKM increased soil fertility and enhanc the nitrogen supplying capability of paddy soils.There was extremely significant linear positive correlation between available nitrogen,ammonium nitrogen,nitrate nitrogen,microbial biomass nitrogen and total nitrogen in A,P horizons of red paddy soil.Therefor,combination of organic and inorganic fertilizer can promote increasing the content of nitrogen composition prominently,which was basic approach to increasing the fertility of soil nitrogen.