Effect Of The Double Cropping Rice Planting Method And Straw Returning To Field On Late Rice Growth And Soil Carbon Pool

In order to provide the basis for the selection of high yield and high efficiency cultivation methods of double cropping rice,The effects of different sowing methods and straw returning on the growth and yield of double cropping rice were compared,and the effects of early rice straw returning and sowing on greenhouse gas emissions in late paddy field and soil carbon pool were analyzed,Straw returning to the field was the main treatment factor,and sowing and planting was the secondary treatment factor.The main treatment factors were straw returning to the field,the sowing and planting method was the secondary treatment factor,the main treatment factor was the two levels of straw returning to the field?N 1?and not returning to the field?N 0?,and the secondary treatment factors were the following four levels:hand planting?T1?,throwing and planting?T2?,machine planting?T3?and direct seeding?T4?,through field and plot experiment,Here are the main results:?1?T3 early rice yield reached 6737.40kg/hm²,and it was higher 4.23%²1.87%than other processing.The main reason was that the seed setting rate increased by 4.25%¹0.34%compared with other treatments.?2?N1T3 late rice yield reached 7264.5 kg/hm²,that was 7.26%,26.16%,4.98%,15.21%,4.67%,23.42%and 11.09%higher than N0T1,N0T2,N0T3,N0T4,N1T1,N1T2and N1T4,The main reason was that the grain number per panicle and 1000-grain weight of N1T3 increased by 0.73%²4.73%and 0.38%³.35%higher than that of other treatments.?3?Under different seeding and planting modes,the direct seeding of tillage was higher than that of hand planting,throwing planting and machine inserting leaf area index3.24%²5.45%,but at booting stage,full heading stage and milk ripening stage,the highest planting rate was 2.66%³7.22%,1.58%²3.17%and 2.16%²7.15%compared with the other 3 planting methods.There was significant difference in dry matter accumulation at the booting stage,but on the tillering stage,heading stage and milking stage were not affected.?4?The photosynthetic rate of rice at booting stage,full heading stage and milk stage was higher than that of no returning field,5.07%²6.07%,1.3%¹3.47%and8.16%²5.33%.Under the sowing and transplanting way,the photosynthetic rate of hand planted rice at booting stage and full heading stage was the largest,higher than that of the other 3 planting modes,0.7%²0.9%and 1.85%¹9.01%respectively.?5?N1T2 has the highest cumulative emission of N₂O,which runs up to1.37kg/hm²,compared with other processing,which improved 0.48%³6.42%,and the difference from N1T4 was not significant,but there were significant differences with other treatments,N1T3 has the highest cumulative emission of CH₄,that run up to 405.94kg/hm²,it increased 7.23%⁹4.20%compared with other treatments,and was significantly different from other treatments.The warming potential?GWP?of N1T3 is the largest,reaching11249kg/hm²,N1T3 increased by 15.02%¹02.21%compared with other treatments,and the difference with other treatments reached a significant level.The greenhouse gas emission intensity?GHGI?of N1T3 was the largest,reaching 1.72kg/kg,which was increased by12.45%⁷8.83%compared with other treatments.The cumulative emission of CH4,the cumulative emission of N2O,GWP and GHGI in the same planting method were significantly higher than those in the non returning fields,including 7.24%³0.96%,8.94%¹6.06%,7.70%³0.16%and 5.91%²7.22%,respectively.?6?Straw returning significantly increased soil organic carbon?SOC?and soil active organic carbon?EOC?content;In the 0⁵cm soil layer,the SOC and EOC content in the paddy field returned to the field rather than the field,which increased 0.58%³.96%and10.98%³1.96%;Under straw returning,EOC content in 0⁵cm and 5¹0cm paddy soil was higher than that in direct seeding and throwing planting.However,there was no remarkable discrepancy in soil EOC content between 10²0cm treatments,under the same seeding and planting mode,the CPMI of straw returned to field was 12.77%²6.33%higher than that of straw not returning to field,and the difference was significant.However,there was no significant difference in soil CPMI between different seeding and planting methods under straw returning.In conclusion,the insertion of straw returning machine is beneficial to increase the yield.The hand planting of straw not returning field was beneficial to reducing greenhouse gas emission.Considering the rice yield,greenhouse gas emission reduction and carbon sequestration effect,the straw returning machine planting mode was the best.