Effects Of Winter Green Manure Crops With And Without Chicken Grazing On CH₄ And CO₂ Emissions,Soil Nutrients And Yield In A Double-Crop Rice Paddy Field In South China

This study is to examine the effects of the crop rotation system"Winter green manure-double cropping rice"and the"winter planting and breeding-double cropping rice"in the short term on CH₄ and CO₂ emissions,soil nutrients and yield under a high value platform of combining planting and breeding.The goal is to return green manure and chicken manure to soils and reduce the amount of fertilizer during the rice growing period.CH₄ and CO₂ emissions were measured using the static chamber/greenhouse gas analyzer,and its net ecosystem CO2 exchange（NEE）,ecosystem respiration（Reco）and total primary productivity（GPP）were discussed.The following conclusions were drawn:（1）The CO₂ cumulative emission ofdouble cropping rice planting milk vetch and chickens grazings treatment were higher than winter fallow treatment,but significantly reduced CH4 cumulative emissions at the same time（P<0.05）.Planting ryegrass treatment can reduce CO2 and CH4 emissions.（2）Compared with the winter fallow-double cropping rice,winter green manure（milk vetch/ryegrass）-double cropping rice and the winter planting（milk vetch/ryegrass）and breeding-double cropping rice has promoted the net ecosystem exchange（NEE）and the total primary productivity（GPP）,but also increased the respiration of the ecosystem.（3）Compared with the winter fallow-double cropping rice,the early and late rice actual production of green manure combined with the chicken-double cropping rice and green manure-double cropping rice were increased 7.45%¹2.95%and 9.75%¹7.21%,respectively.The effect of improving the yield of green manure combined with the chicken-double cropping rice effect was better than green manure or winter fallow-double cropping rice.（4）In the dynamic process of the whole system,the overall trend of soil microbial biomass C,N and dissolved organic C,N showed that green manure combined with the chicken-double cropping rice>green manure-double cropping rice>fallow-double cropping rice,with significant difference between groups.Compared with the winter fallow-double cropping rice,the green manure combined with the chicken-double cropping rice system can significantly improve the soil microbial biomass carbon,nitrogen and dissolved organic carbon,nitrogen,which increased by 34.59%⁴0.49%,65.66%⁶7.29%,26.92%²7.13%and 55.15%⁶6.66%,respectively.Compared with green manure-double cropping rice,the greenmanurecombinedwiththechicken-double-croppingriceincreased1.11%¹2.13%,13.11%²4.33%,9.70%¹0.07%and 14.56%²3.33%.（5）Compared with the winter fallow-double cropping rice,the green manure combined with the chicken-double cropping rice system can significantly improve the organic matter,total nitrogen content,NH₄⁺-N and NO₃^--N content in double cropping paddy fields,which increased by 17.36%²2.95%,73.73²50.48%,76.36%⁸5.11%and 67.89%⁷0.05%,respectively.Compared with green manure-double cropping rice organic matter and total nitrogen,NH₄⁺-N and NO₃^--N content were increased by 1.20%⁹.72%,5.26%⁷7.78%,19.47%⁴9.75%and 20.40%⁴3.05%,respectively.（6）"Winter planting ryegrass-double cropping rice"can significantly improve the available phosphorus content,which is 57.99%higher than that of"winter fallow-double cropping rice".Therefore,the winter field planting milk vetch and chickens grazings-double cropping rice was an effective system to reduce the amount of carbon emissions and fertilizer,and improve the soil nutrient and rice yield,significantly.