BEIJING, Dec. 22 (Xinhua) -- Chinese researchers have concluded that the microbial biomass carbon content of paddy soils is almost twice that of upland soils.
Artificial wetland soils, or paddy soils, were formed with long-term rice planting in tropical and subtropical regions. Compared with upland soils, paddy soils reserve more microbial biomass, while the internal mechanism still needs to be explored.
The researchers from the Institute of Subtropical Agriculture of the Chinese Academy of Sciences conducted a meta-analysis of published literature on the microbial biomass content in continuous paddy soils and paddy-upland rotation soils as compared to that in adjacent upland soils.
The result showed that the microbial biomass carbon content in paddy soils was double that in upland soils.
The proportion of microbial biomass carbon in total soil organic carbon in paddy and upland soils was 2.5 percent and 2.1 percent, respectively, according to the research article published in the journal Agriculture, Ecosystems and Environment.
Despite the higher temperature and better water availability, microbial biomass turnover was 1.1 to 1.6 times slower in paddy soils than in upland soils because of oxygen limitation, explained the article.
Paddy-upland rotation soils undergo oxic-anoxic cycles and consequently can absorb and coprecipitate organic compounds with iron oxides as an additional advantage for carbon stabilization.
The researchers confirmed that the reduced microbial activity and slower microbial turnover under oxygen-limited conditions lead to the higher microbial biomass content in paddy soils. Enditem
