红壤稻田土壤溶解有机碳含量动态及其生物降解特征

DYNAMICS AND BIODEGRADATION OF DISSOLVED ORGANIC CARBON IN PADDY SOILS DERIVED FROM RED CLAY

本文通过田间采样分析和室内培育试验,研究了不同利用年限的3种红壤水田土壤中溶解有机C(DOC)的含量动态和生物降解特征.结果表明:土壤DOC的含量随土壤深度而降低,二者具有显著负相关性.0～30cm土壤DOC的含量及其占总C比例随土壤有机C含量的升高而增大.DOC的季节变化明显,主要与气候因素有关;降雨和灌水可显著提高DOC的含量,是落干时含量的1.44～2.50倍.淋溶试验结果表明,从试验开始,淋滤液中DOC的浓度呈增加趋势,至21天时达到最大,其后又趋下降.在49天的培养期内,DOC的分解速率为31%～58%,其中低分子量组分能在数天内降解掉.不同土壤间DOC的分解速率有明显差异.

Dynamics and transformation of dissolved organic carbon (DOC) in paddy soils of the red soil region were studied by sampling analysis and laboratory incubation. The results showed that DOC content decreased significantly with soil depth. DOC content and DOC/TOC(%) in 0~30cm layer increased with soil organic carbon content. Irrigation and rainfall could increase soil moisture. As a result DOC was 1.44 to 2.5 times higher under irrigation (submersion) than drainage (aerobic condition). During the 49 days of incubation, decomposition rate of DOC was 31%~58%, which differed from soils. Low molecular fractions could be mineralized in a few days.