Sheng Hao, Zhou Ping, Yuan Hong, Liao Chao-Lin, Huang Yun-Xiang, Zhou Qin, Zhang Yang-Zhu
College of Resources & Environment, Hunan Agricultural University, Changsha 410128, China.
Huan Jing Ke Xue. 2013 Apr;34(4):1576-82.
The soil microbial biomass carbon (C(mic)), one of the most active components of soil organic carbon (C(org)), is an effective indicator of soil quality. In the present study, five subtropical paddy soils developed from different parent materials were selected, and the distribution of C(mic) through the profiles was studied, as well as the relationship of C(mic) with C(org) and soil nutrients. The results showed that the contents of C(org) and C(mic) decreased markedly with increasing soil depth, ranging from 2.45 g x kg(-1) to 26.19 g x kg(-1) and from 4.55 mg x kg(-1) to 1 691.75 mg x kg(-1), respectively. They mainly concentrated in the surface layer (plough horizon and plough pan). The content of C(mic) varied significantly in paddy soils developed from different parent materials, with the highest one in yellow clayey soil, and the lowest ones in alluvial sandy soil and reddish yellow clayey soil. This was on the contrary to the distribution of C(org) in the surface paddy soils, since the reddish yellow clayey soil and alluvial sandy soil showed higher contents while other types of paddy soils exhibited similar contents of C(org). Notwithstanding, C(mic) was still controlled by the quantity of C(org) and positively correlated with C(org). The ratio of C(mic) to C(org)(C(mic)/C((org)) decreased with increasing soil depth and differed in the plough horizon between different paddy soils, with lower values in alluvial sandy soil (2.11%) and reddish yellow clayey soil (1.37%) but higher value in reddish yellow clayey soil I (8.24%). It indicated that the microbial substrate availability in alluvial sandy soil and reddish yellow clayey soil was lower than those in reddish yellow clayey soils. The content of C(mic) was significantly positively correlated with total nitrogen, alkali-hydrolyzable N and Olsen-P, but was irrelevant to available K. It is implied that the C(mic) was not only controlled by C(org), but also complicatedly interacted with soil nutrients in paddy soils.
土壤微生物量碳（C(mic)）是土壤有机碳（C(org)）最活跃的组分之一，是土壤质量的有效指标。在本研究中，选取了五种由不同母质发育而来的亚热带水稻土，研究了C(mic)在土壤剖面中的分布以及C(mic)与C(org)和土壤养分的关系。结果表明，C(org)和C(mic)含量均随土壤深度增加而显著降低，范围分别为2.45 g·kg⁻¹至26.19 g·kg⁻¹和4.55 mg·kg⁻¹至1691.75 mg·kg⁻¹。它们主要集中在表层（耕作层和犁底层）。不同母质发育的水稻土中C(mic)含量差异显著，黄黏土中含量最高，冲积砂质土和红黄色黏土中含量最低。这与表层水稻土中C(org)的分布相反，因为红黄色黏土和冲积砂质土中C(org)含量较高，而其他类型水稻土中C(org)含量相似。尽管如此，C(mic)仍受C(org)数量的控制，并与C(org)呈正相关。C(mic)与C(org)的比值（C(mic)/C((org))）随土壤深度增加而降低，不同水稻土耕作层中的该比值也有所不同，冲积砂质土（2.11%）和红黄色黏土（1.37%）中的值较低，而红黄色黏土I中的值较高（8.24%）。这表明冲积砂质土和红黄色黏土中微生物底物的有效性低于红黄色黏土。C(mic)含量与全氮、碱解氮和 Olsen-P 显著正相关，但与速效钾无关。这意味着C(mic)不仅受C(org)控制，还与水稻土中的土壤养分存在复杂的相互作用。
