有机物料在维持土壤微生物体氮库中的作用

Effects of organic materials on maintaining soil microbial biomass nitrogen

采用室内和田间培养试验 ,研究了有机物料矿化过程中土壤微生物体氮的变化。测定结果表明 ,有机物料对矿化过程和微生物体氮的影响 ,既与有机物料本身性质和组成有关 ,也与土壤肥力水平和施氮与否有关。加入 C/N比高的有机物料后 ,微生物对矿质氮的净固定持续时间长 ,而加入 C/N比小的则固定时间短 ;高肥力土壤上的固定时间比低肥力土壤短。不同有机物料对土壤微生物体氮的影响不同。从加入绿豆茎叶、小麦茎叶、未腐解马粪、腐熟马粪、腐熟猪粪到厩肥 ,土壤微生物体氮依次减小 ,提供的有效能源物质丰富 (如绿豆茎叶 )或 C/N比较高 (如小麦茎叶 )时影响效果突出。土壤肥力不同 ,有机物料对微生物体的影响效果不同 ,在低肥力土壤上的效果突出 ,约为高肥力土壤的 4倍。因此 ,在评价有机物料对土壤微生物体氮的影响时 ,既考虑有机物料的性质和组成 ,也考虑土壤肥力水平、矿质氮含量和培养时期。

The incubation experiments conducted in laboratory and fields showed that the effects of mineralization processes of organic materials on soil microbial biomass nitrogen were closely related to the properties and constitution of organic materials and relied on the soil fertility and nitrogen application. Adding organic material with high C/N ratio, the net fixation of fertilizer nitrogen by microorganisms maintained a longer period, on the contrary the period was shorter. The fixation period in soil with high fertility was shorter than in those with low fertility. Different organic materials had different impacts on soil microbial biomass nitrogen. The soil microbial biomass nitrogen decreased in sequence from adding mung bean straw, wheat straw, non decayed excrements of horse, excrements of sheep, decayed excrements of horse, decayed excrements of pig to manure. The organic material with rich avialable energy substance (e.g. mug bean straw) or with higher C/N ratio (e.g. wheat straw) had greater impacts on soil microbial biomass nitrogen than other organic materials. In low fertility soils, the effects of organic materials on soil microbial biomass nitrogen was rather apparent, about 4 times of high fertility soil.Thereby, it's essential for considering the properties and constitution of organic materials,soil fertility and mineral nitrogen content, and incubation time to estimating the effects of organic materials on soil microbial biomass nitrogen.