鄱阳湖不同耕作时间水稻土微生物量碳比较

A Comparative Study on Microbial Biomass Carbon of Paddy Soils among Different Cultivated Years in Poyang Lake Area

采集鄱阳湖湖积母质水稻土剖面样品,比较不同土层深度水稻土微生物量碳变化特征及不同耕作时间下水稻土微生物量碳剖面总含量.结果表明:(1)水稻土微生物量碳含量剖面分布变化规律为:土层越深,含量越低,其中耕作层微生物碳量均占到了50%以上;(2)水稻耕种时间越长,土壤的微生物量碳含量越高,但不同耕作年限的增幅有所差异:与30年耕作时间水稻土比较,50年耕作时间水稻土的增幅达40.87%,70年耕作时间较50年水稻土的增幅为31.83%,而90年耕作时间较70年水稻土微生物量碳的增幅则为17.54%;(3)随着水稻土耕作时间的推移,土壤的有机碳总量、含水量上升,土壤的黏粒比重有所下降,这有利于改善土壤微生物的生存环境,进而提高土壤的微生物量碳含量.

The section samples of paddy soil derived from lake sediment in Poyang Lake were collected to conduct to a comparative study which is worked on change characteristics of microbial biomass carbon at different depth of paddy soil, the total section content of microbial biomass carbon in paddy soil cultivated at different periods as well. The resuhs showed that ： （ 1 ） The distribution of the microbial biomass carbon content in sections is that the deeper the soil is, the lower the content is. Particularly, the microbial biomass carbon content in plough horizon accounts for over 50%. （2） With the cultivation years growing, the content of microbial biomass carbon increases. But there are different variation ranges for paddy soil with different cultivation years. Compared with the paddy soil cultivated for 30 years, one for 50 years has the microbial biomass carbon content increased by 40.87%. While one for 70 years is increased by 31.83% compared with that for 50 years, and one for 90 years increases by 17.54% compared with that for 70 years. （ 3 ） With the cultivation time goes by, the total content of organic carbon and water in soil will be increased and the proportion of clay in the soil will be decreased. Which is beneficial to improve the living condition of soil microbes. The content of soil microbial biomass carbon will be increased accordingly.