Sole and Combined Application of Phosphorus and Glucose and Its Influence on Greenhouse Gas Emissions and Microbial Biomass in Paddy Soils

Soil microbial activities are consistently restricted not only by phosphorus availability but also by microbial carbon requirements. Therefore, an incubation experiment was conducted with three soils (QY1, QY2 and QY3) selected on the basis of phosphorus limitation. Results revealed that high N2O emissions, 17.44 µg kg−1, were measured in phosphorus-deficient soil with addition of glucose. In phosphorus-adequate soils, the peaks of N2O emission values in the glucose addition treatment were 20.8 µg kg−d and 24.7 µg kg−1, which were higher than without glucose-added treatments. CH4 emissions were higher with glucose addition, at 1.9 µg kg−e in phosphorus-deficient soil and 1.52 µg kg−e and 2.6 µg kg−1 in two phosphorus-adequate soils. Phosphorus added to deficient and adequate soil significantly increased the cumulative CH4 and N2O emissions compared to the solely glucose added soil and the combination of glucose with phosphorus. Glucose addition significantly increased microbial biomass carbon (MBC) but decreased microbial biomass phosphorus (MBP), especially in the phosphorus-adequate soil. For MBC, the highest value obtained was 175.8 mg kg−1, which was determined under glucose addition in phosphorus-adequate soil. The soil pH increased with glucose addition but decreased with phosphorus addition in phosphorus-deficient soil. The soil organic carbon (SOC) content was significantly affected by glucose addition in the phosphorus-deficient soil. Available phosphorus (AP) was highly influenced by phosphorus addition but did not appear to be affected by glucose addition. From the current study, we concluded that sole phosphorus and glucose addition increase CH4 andN2O emissions in phosphorus-deficient and also in phosphorus-adequate paddy soils. Further study will be conducted on sole and interactive effects of glucose and phosphorous on soil with plants and without plants.