施肥对金沙江干热河谷退化草地土壤微生物的影响

Effect of Fertilization on Soil Microorganism of Deteriorated Grassland in Dry-Hot Valley Region of Jinsha River

在金沙江干热河谷区的退化草地上进行了2年的氮磷施肥试验,试验结束后分析了土壤特性及土壤微生物数量和生物量的变化。结果表明,在施氮量为5 ,15g/ (m2 ·a)时,土壤微生物的数量和生物量均没有明显变化,而当施氮量增加到2 5g/ (m2 ·a)时,土壤微生物的数量和生物量比对照明显增加。施磷没有引起土壤微生物数量和生物量的明显增加。施氮和施磷均没有引起土壤细菌、真菌和放线菌组成的变化。这表明氮虽然影响土壤微生物的数量,但对土壤微生物的组成没有影响。施氮导致土壤硝态氮增加,但对氨态氮影响不大,硝态氮可能是影响土壤微生物数量的重要因素。施氮和施磷后植物群落地上生物量均出现增加的趋势,但土壤有机质没有明显增加。施氮和施磷也没有引起土壤pH和含水率的明显改变。我们的试验结果表明,在干热河谷退化草地生态系统。

The fertilization of nitrogenous fertilizer and phosphate fertilizer experiment was carried out on the deteriorated grassland in the dry-hot valley region of the Jinsha River. After the experiment, quantity and biomass of soil microorganism as well as soil property were surveyed. The results showed, in the treatments of 5,15 g/(m^2·a) nitrogenous fertilizers, the variance of soil microorganism in quantity and biomass, compared with control, was not significant. But in the treatment of 25 g/(m^2·a) nitrogenous fertilizers, there were significantly incremented. Quantity and biomass of soil microorganism did not increase significantly under phosphate fertilization. Fertilization of nitrogenous fertilizer and phosphate fertilizer also didn't bring about the significant variance of the proportions of bacteria, fungus, and actinomycetes to the gross of microorganism. This indicated that nitrogenous fertilizer could affect the quantity of soil microorganism, but could not affect the composition of soil microorganism. Fertilization of nitrogenous fertilizer could increase the content of nitrate nitrogen, but had little affection on the content of ammoniacal nitrogen. After the fertilization of nitrogenous fertilizer and phosphate fertilizer, the aboveground biomass of plant community appeared the trend of increase, but the content of soil organic matter, soil pH, and the water content had no significant change. Our results indicated that the restoration of the soil microorganism in the deteriorated grassland of the dry-hot valley region was difficult by the short-term fertilization of chemical fertilizer.