不同施肥处理下土壤水溶性有机碳含量及其组成特征的研究

CONTENTS OF WSOC AND CHARACTERISTICS OF ITS COMPOSITION UNDER DIFFERENT FERTILIZATION SYSTEMS

长期不同施肥处理下 ,土壤水溶性有机碳 (WSOC)含量范围为 3 2 1～ 45 5mgkg- 1,大小顺序为NPK +4 5 0 0kg稻草 >NPK +2 2 5 0kg稻草 >对照 >NPK ;WSOC占土壤总有机碳 (TOC)百分比的范围为0 1 5 %～ 0 1 9% ,大小顺序为NPK +4 5 0 0kg稻草≈对照 >NPK +2 2 5 0kg稻草 >NPK。土壤中WSOC的含量与TOC、微生物生物量碳 (SMBC)的含量都呈显著性正相关。13C核磁共振 ( 13C NMR)的研究结果表明 ,WSOC都主要是由碳水化合物C、羧基C和长链脂肪C组成。不同施肥处理下 ,WSOC和SMBC占TOC百分比的变异系数 (CV)都小于它们在土壤中绝对含量的变异系数 ,且WSOC/TOC的变异系数大于SMBC/TOC。WSOC/TOC是反映不同施肥处理下土壤有机质质量的一个较好指标。

Under a long-term experiment on different fertilization treatments, the contents of water-soluble organic carbon (WSOC) in the soil ranged from 32.1 to 45.5 mg kg -1, following the order of NPK+4 500 kg rice straw>NPK+2 250 kg rice straw>CK>NPK. The percentages of WSOC to total soil organic carbon (TOC) ranged from 0.15% to 0.19%, following the order of NPK+4 500 kg rice straw≈CK>NPK+2 250 kg rice straw>NPK. The contents of WSOC had significantly positive correlations with both TOC and soil microbial biomass carbon(SMBC). 13C-NMR results showed that WSOC were mainly composed of carbohydrates carbon, carboxyl carbon and long-chain aliphatic carbon. Under different fertilization treatments, the coefficients of variation (CV) of WSOC/TOC and SMBC/TOC were lower than those of their absolute contents in soil. Furthermore, the CV of WSOC/TOC was higher than that of SMBC/TOC. The percentage of WSOC to TOC was a good indicator of the quality of soil organic matter under different fertilization treatments.