Benefits of SOM in agroecosystems: the case of China.

Abstract

AbstractWhile soil organic matter (SOM) content can be directly correlated with crop yield at the country/province level, abundance in SOM content may also be linked to economical output such as gross domestic production per capita at the county or province scale. Benefits of SOM include increasing nitrogen (N) efficiency, enhancing soil biodiversity and the health of soil food web systems, as well as aiding the degradation of toxic pollutants. Among these, the enhancement of the soil microbial community, and hence microbiochemical functions, is of key importance for productivity in croplands. Many studies have shown that the metabolic quotient of the soil microbial community (the specific quotient of soil respiration to SOM content) is unchanged or lowered as SOM accumulates. In order to characterize these benefits, several parameters are needed: (i) microbial abundance on the base of SOM content (microbial quotient, %); (ii) soil basal respiration to microbial biomass carbon (C); and (iii) normalized enzyme activity on the bases of soil microbial biomass carbon and soil organic carbon. As yet, there is no evidence that there is an SOM limit for Asian agricultural soils. A conceptual model of the role of SOM and benefits from the interaction with mineral particles and the formation of aggregates is hypothesized to gain an understanding of the benefits of SOM in croplands.