期刊
PLANT AND SOIL
卷 338, 期 1-2, 页码 127-141出版社
SPRINGER
DOI: 10.1007/s11104-010-0554-4
关键词
Organic matter; Root litter; Decomposition; Stable isotopes; Physical fractionation; Subsoil horizons; Temperature; Moisture
资金
- Higher Education Commission (HEC) of Pakistan
- Region Poitou-Charentes: Excellence Environnementale et Developpement des Eco-Industries
Mechanisms leading to high mean residence times of organic matter in subsoil horizons are poorly understood. In lower parts of the soil profile root material contributes greatly to soil organic matter (SOM). The objective of this study was to elucidate the decomposition dynamics of root-derived C and N in different soil depths during a 3 year field experiment and to examine the importance of different protection mechanisms as well as abiotic factors for the decomposition dynamics. Additionally, we assessed the effect of root litter addition on native SOM. Our conceptual approach included the exposure of litterbags with C-13 and N-15 labeled wheat root material mixed to loamy agricultural soil at three different soil depths (30, 60 and 90 cm). During the incubation period, we monitored soil temperature, humidity and the incorporation of root derived C and N into the soil microbial biomass and physical SOM fractions. Our results showed that abiotic decay conditions were better in subsurface horizons compared to the topsoil. Root litter addition significantly increased the size of microbial biomass in all three soil horizons. In the topsoil, root-derived C decomposition was significantly higher in the first 6 months of incubation compared to subsoil horizons. In 60 and 90 cm depths, a lag phase with development of soil microbial biomass seemed to be prevailing before decomposition was activated. For root-derived N, similar decomposition kinetics could be observed in top- and subsoil horizons. Despite of higher SOM contents, better soil structure and higher microbial activity in the topsoil horizon compared to subsoil horizons, the amounts of root-derived C and N remaining after 3 years were similar for all three depths. Most of the root-derived C and N was present as organo-mineral complexes or occluded in soil aggregates (oPOM), illustrating similar importance of these two protection mechanisms in all three soil depths. Addition of fresh root litter caused small losses of native soil C whereas native N was retained. We conclude that despite of similar SOM protection mechanisms, there are distinct differences in decomposition dynamics of root litter between top- and subsoil horizons. In the long run, the better abiotic decay conditions prevailing in subsoil horizons may compensate for their poorer physico-chemical characteristics.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据