【摘要】 于1998年11月,用砂滤管法研究了水旱轮作条件下黄棕壤加入杂交狼尾草秸秆后有机碳(土壤原有碳+秸秆碳)的分解状况和微生物量碳的动态变化,为期1年。结果表明,有机碳的分解前期较快,7d时有机碳的分解量即占到年分解总量的37%～41%,以后逐渐变慢;淹水种稻后又有一个小的分解高峰,随后分解速率再次逐步降低,1年后有机碳被分解了5 45%～17 32%。有机碳的分解量随秸秆加入量的增加而增加,施加秸秆在加速有机碳分解的同时也弥补了土壤原有碳的损失。试验开始后土壤微生物量碳迅速上升,接着随时间延长而减少,种稻后土壤微生物量碳再次上升,随后又随时间延长而减少。土壤有机碳的微生物利用率为0 96%～3 38%,增施有机肥可提高土壤微生物对有机碳的利用率。土壤微生物量碳的周转率为1 00～1 13a-1,增施秸秆可使土壤微生物量碳及其周转率增加,从而提高土壤的保肥和供肥性能。有机碳的分解进程与微生物量碳的动态变化趋势一致,说明有机碳分解的快慢是土壤微生物活动强弱的外在表现。更多还原

【Abstract】 Decomposition of organic carbon,i.e.soil native carbon plus hybrid elephant grass straw carbon,and turnover characteristics of soil microbial biomass carbon(SMBC)in a yellowbrown earth were studied by using porous carborundum tube method under condition of rotation between upland crop and paddy rice for 1 year(1998～1999).Results indicated that decomposition of organic carbon proceeded rapidly at the early period and then slowed down.The decomposition amount of organic carbon during the first 7 d made up 37%～41% of that during a whole year;decomposition of organic carbon proceeded rapidly again after rice was transplanted,then slowed down.The original organic carbon was decomposed in total of 545%～1732% after 1 yearThe decomposition amount of organic carbon increased with the increment of straw added.Straw application not only accelerated the decomposition of organic carbon,but also compensated the loss of soil native carbon.SMBC increased rapidly at the early period and then decreased,and increased again after rice was transplanted,and then decreased gradually.The utilization rate of organic carbon by soil microorganisms varied from 096% to 338%,and it could be improved greatly due to straw application.Turnoverrate of SMBC changed from 100 to 113 a-1.Straw addition could promote SMBC and its turnover rate,and enhance the ability of supply and maintenance of soil nutrients.Decomposition patterns of organic carbon showed similar to dynamics of SMBC,which indicated that the decaying rate of organic carbonwas the external expression of soil microbial activities.更多还原