Effects Of Different Fertilization Patterns On Yield、Soil Fertility And Greenhouse Gas Emission Of Ratoon Rice In Medium-low Yield Fields

The area of medium-low yield fields in China accounts for about 68% of the total arable land,and the area of medium-low yield fields in Hubei Province accounts for about 73% of the total arable land.Improvement of medium-low yield fields is one of the main ways to increase graining output.Ratoon rice "one kind of double harvest" is an important model of planting which can both increase multiple cropping index and graining yield in southern China.However,there are few studies on the synergistic improvement of yield and soil fertility of ratoon rice in medium-low yield fields.Therefore,the purpose of this study is to explore the effects of different fertilization models on the yield,soil fertility and greenhouse gas emissions of ratoon rice in medium-low yield fields.The field experiment was conducted in Zhenggongta Village,Huaqiao Town,Wuxue City,Hubei Province in 2022.The split zone design was adopted,with the fertilization pattern as the main area and rice varieties as the secondary area,repeated three times.The tested varieties were Liangyou 6326 and Huang Huazhan.Fertilization treatments include no application of nitrogen fertilizer;normal fertilization in the main season and only bud promotion fertilizer in the ratoon season;normal fertilization plus two seasons straw returning to the field;normal fertilization added organic fertilizer plus two seasons of straw returning to the field;normal fertilization added organic fertilizer plus two seasons straw return to the field and plant green manure rape in winter.The main test results are as follows:(1)The application of organic fertilizer had no significant effect on yield,yield components and nitrogen use efficiency in the main season.No application of seedlings fertilizer significantly decreased the number of spikelets per panicle by26.0% and 1000-grain weight by 3.5% in ratoon season,so that the yield in ratoon season decreased by 22.7%.Straw returning in the main season significantly reduced the number of panicles by 14.3%,thus significantly reducing the yield by 11.3%.There was no significant difference in yield and yield components between the treatment of organic fertilizer and straw returning in the main season and normal fertilization.(2)The application of organic fertilizer significantly increased the content of soil organic matter and available potassium by 9.6% and 46.7% in the mature period of the main season.Straw returning in the main season significantly increased the soil organic matter content in the mature stage of the ratoon season by 8.6%.And the application of base fertilizer plus straw returning in the main season significantly increased the soil organic matter content and available potassium content by 10.9%and 24.3%.(3)The fertilization patterns mainly affected greenhouse gas emissions from paddy fields by affecting the soil organic matter.Both of CH4 in the main season of ratoon rice and cumulative emissions of CH4 and CO2 in ratoon season are significantly positively correlated with soil organic matter matter.The application of organic fertilizer increased the cumulative CH4 emissions by 21.5% in the main season,but there was no significant difference in N2 O emissions.Straw returning in the main season had no significant effect on greenhouse gas emissions in the ratoon season.The application of organic fertilizer plus straw returns in the main season significantly increased CH4 and CO2 emissions by 22.4% and 10.7% in the ratoon season,while no seedlings fertilizer significantly decreased N2 O emissions in the ratoon season.The application of organic fertilizer plus straw returning in the main season significantly increased the global warming potential of the whole growth period by 12.9%,and straw returning in the main season had no significant effect on the global warming potential of the whole growth period.Except for no nitrogen fertilizer,there was no significant difference in the global warming potential of unit yield between the main season and the ratoon season.To sum up,the application of organic fertilizer plus straw returning in the main season has a stable and high yield,which can improve the soil fertility of paddy field,and there is no significant difference between the greenhouse effect and the conventional model.It has important guid significance for promoting the sustainable development of ratoon rice in medium and low yield fields.