Influence of phosphorus application on methane emission and production in flooded paddy soils

In a field study, phosphorus applied as single superphosphate (SSP) distinctly inhibited CH4 emission from a flooded field plot planted to rice. In subsequent laboratory studies, application of P at 50 and 100 μg g−1 dry soil as K2HPO4 stimulated CH4 production in a P-deficient soil, while there was no such stimulation in P-normal alluvial soil. CH4 production in soils depended on the source of P applied as evidenced by stimulation with K2HPO4 or Jordan rock phosphate, while Mussorie rock phosphate and SSP were inhibitory. The results indicate that the S content of the P sources determines the extent of stimulation or inhibition of CH4 production. Moreover, supplementary addition of K2SO4, even with K2HPO4, mimicked the inhibitory effect of SSP on CH4 production. In practice, use of SSP in rice cultivation, in addition to supplying P to the growing crop, could mitigate CH4 production and emission through its S content.