Rice-fish symbiosis patterns with different densities affect methane emissions from double-cropping paddy fields
The objective of this study is to explore the effects of rice-fish symbiosis patterns at different densities on methane(CH4)emissions and organic carbon in double cropping paddy fields.In this study,a field experiment was conducted in Lukou Town,Changsha County,Hunan Province from 2022 to 2023,and three treatments were set up:conventional planting of double cropping rice without fish culture(CK),double cropping rice fish farming of 3 000 fish·hm-2(DY1)and 6 000 fish·hm-2(DY2),and the regional experimental design was adopted.The effects of rice-fish symbiosis patterns at different densities on CH4 emissions and soil organic carbon(SOC),water-soluble organic carbon(WDOC)and microbial biomass carbon(MBC)in double-cropping paddy fields were analyzed.The results showed that compared with CK,the two-year rice-fish symbiosis model increased the seasonal cumulative emission flux and annual cumulative emission of CH4.Compared with the different densities of rice-fish treatments(DY1 and DY2),the cumulative annual emissions of CH4 in 2022 and 2023 of DY1 treatment were significantly higher than those of DY2 treatment by 17.67%and 13.35%(P<0.05).In 2022,the early and late rice maturation stages increased the soil SOC content by 8.18%-14.10%and 47.26%-56.42%,respectively.In 2023,it increased by 22.00%-22.77%and 23.74%-24.91%,respectively.When the soil WDOC content reached the peak,compared with CK,the early and late rice stages of rice-fish treatment in 2022 increased by 133.39%-179.35%(P<0.05)and 27.72%-40.78%(P<0.05),respectively,and the early and late rice stages of rice-fish treatment in 2023 increased by 6.98%-14.16%(P<0.05)and 68.51%-74.83%(P<0.05),respectively.In 2022,the MBC content of rice-fish treatment soil increased significantly by 544.86%-719.41%(P<0.05)in early rice and 15.89%-32.68%(P<0.05)at the peak of late rice,and the MBC content in early rice in 2023 changed slightly,and DY2 increased significantly by 210.35%compared with CK in late rice(P<0.05).In conclusion,the rice-fish symbiosis pattern increase the contents of soil SOC,WDOC and MBC and promoted CH4 emissions,which decrease with the increase of fish density.This study found that the effect of rice-fish symbiosis on CH4 emission reduction in double-cropping paddy field has important promotion significance in production practice,and the effect is best when the density is 6 000·hm-2.
万方数据
维普
