红壤微生物生物量C周转及其研究

采用14 C底物标记技术测定了三种不同质地 (红砂土菜地、黄筋泥桔园和茶籽园 )的红壤微生物生物量C的周转期。结果表明 ,在 2 5℃、5 0 %田间持水量培养条件下 ,三种红壤微生物生物量C的周转期分别为 80天、1 39天和 1 70天。周转期与粘粒含量关系较为密切 ,砂质土壤的周转期较粘粒土壤短 ,提示砂质土壤有机质易被微生物降解 ,有利于养分的迅速释放 ,而粘粒土壤则更有利于养分的持留。周转期与利用方式、pH以及有机质含量无明显相关。红壤微生物生物量C周转期总体上较报道的其他类型土壤微生物生物量C周转期短 ,表明热带—亚热带地区酸性红壤有机质和养分周转相对较快 ,这有可能是造成红壤养分贫瘠的一个原因。根据周转期估算 ,通过微生物年周转的C量 (即年流通量 )为微生物生物量C的 2倍以上

TURNOVER OF MICROBIAL BIOMASS C IN RED SOILS AND ITS SIGNIFICANCE IN SOIL FERTILITY EVALUATION

A 14 C-labelling technique was used to study turnover of microbial biomass C of 3 red soils with different texture, i.e ., vegetable garden of red sandy soil, citrus orchard and tea garden of clayey soil, for which the turnover periods of soil microbial biomass C were 80 days, 139 days and 170 days, respectively. The turnover period was closely related to clay content, and longer in the red sandy soil than in the clayey soils, suggesting that organic matter can be faster decomposed and transformed by microorganisms and nutrients more easily released in the sandy soil, in other words, nutrients may be retained longer in clayey soil. However their turnover period was little affected by land use form, pH and organic matter content.In general, the turnover period for red soils was shorter than that reported for other types of soils, which shows that quicker turnover of organic matter and nutrients went on in acidic red soils of the tropical-subtropical regions and this may be one of the reasons for nutrient deficiency in red soils. To study the turnover of microbial biomass C is quite significant in evaluating and managing red soil fertility.