INFLUENCE OF PHOSPHORUS APPLICATION ON METHANE EMISSION AND PRODUCTION IN FLOODED PADDY SOILS

In a field study, phosphorus applied as single superphosphate (SSP) di stinctly inhibited CH4 emission from a flooded field plot planted to r ice. In subsequent laboratory studies, application of P at 50 and 100 mu g g(-1) dry soil as K2HPO4 stimulated CH4 production in a P-deficie nt soil, while there was no such stimulation in P-normal alluvial soil . CH4 production in soils depended on the source of P applied as evide nced by stimulation with K2HPO4 or Jordan rock phosphate, while Mussor ie rock phosphate and SSP were inhibitory. The results indicate that t he S content of the P sources determines the extent of stimulation or inhibition of CH4 production. Moreover, supplementary addition of K2SO 4, even with K2HPO4, mimicked the inhibitory effect of SSP on CH4 prod uction. In practice, use of SSP in rice cultivation, in addition to su pplying P to the growing crop, could mitigate CH4 production and emiss ion through its S content. (C) 1997 Published by Elsevier Science Ltd. All rights reserved.