Effect of saline patch and organic amendment on methane emission and rice yield in saline paddy field

Abstract

Study on methane emission and saline patch area of Kula Ronghai soil series (Typic Natraqualfs) wasconducted. Two levels of soil salinity: 1) saline patch, and 2) outside-saline patch ; and 3 organic amendments: 1) noamendment (control), 2) rice straw at the rate of 1,000 kg. rai-1, and 3) cow manure at the rate of 1,438 kg. rai-1, werecomposed totally 6 treatments. RD 6 rice seedlings were transplanted. Methane emission rate during the whole ricecycle, electrical conductivity of soil (EC1:5) and rice yield were monitored. Results found that the average methaneemission rate during the whole rice cycle in the saline patch with rice straw and cow manure slightly increased by20-33% compared with no amendment, while outside-saline patch plots with rice straw and cow manure incrediblyincreased by 153-161% compared with no amendment. Regardless of organic amendments, saline patch plots gavesignificantly lower rice yields (77-96 kg. rai-1) than outside-saline patch plots (399-479 kg. rai-1). Results deduced that low seasonal average of methane emission rate occurred in saline patch corresponding to high electricalconductivity. Methanogenesis in saline patch was delayed and methane emission rate was declined. Rice strawand cow manure could not increase yield in both saline patch plots and outside-saline patch plots. In contradictoryquantity of methane emission was enlarged by application of organic amendments particularly outside-saline patchplots.