放牧强度对新麦草土壤氮素分配及其季节动态的影响

通过不同放牧处理对新麦草人工草地土壤氮素分配及其在生长期间的动态研究。结果表明，０～３０ｃｍ土层全氮量月均值的顺序为对照〉重牧〉轻牧〉中牧（Ｐ〈０．０１）。放牧强度对铵未形成显著影响（Ｐ〉０．０５）。０～３０ｃｍ土层随着放牧强度的增加，硝态氮量逐渐增加。放牧区净可矿化氮量大于对照区，其中以中度放牧区最高。０～３０ｃｍ土层土壤微生物生物量氮的顺序为重牧〉对照〉中牧〉轻牧（Ｐ〈０．０５）。

The Distribution and Growing Seasonal Dynamics of Soil Nitrogen Fractions on Russian Wildrye Grass Pasture Under Different Grazing Intensities

The distribution and growing seasonal dynamics of soil nitrogen fraction under light grazing (LG 0. 134hm2/1amb),medium grazing (MG 0. 08hm2/1amb), high grazing(HG 0. 067hm2/1amb), and no grazing (ck) was carried out on a russian wildrye grass(Psathyrostachys juncea (Fishch)Nevski) pasture during growing season (from mid -June-mid September)in 1997. The order of soil total N percentage in layer of 0~ 30cm soilwas CK>HG>LG>MG(P<0. 01). There were no significant difference among ammonianitrogen under different grazing intensities (P>0. 05). Because of the increasing of grazingintensities the content of nitric nitrogen increased in layer of 0~30cm soil. The net mineralizable N of grazing intensity was higher than that of ungrazed, and the content of netmineralizable N of medium grazing intensity was the highest, but there were no significantdifference among them because of short grazing period(P>0. 05), Soil microbial biomass Nin layer of 0,30cm soil was ranked as HG>CK>MG>LG(P<0. 05).