| Rice paddies account for more than 10 percent of global agricultural activity.The increase of CH4 emission due to irrational irrigation mode in traditional rice farming modes,which restricts the green and sustainable development of Chinese rice fields.Nowadays,a large number of studies have proved that water-saving irrigation and oxygenated irrigation in paddy fields can improve the oxygen content in soil and water layer,increase rice yield and reduce CH4 emission in paddy fields.However,due to the inconvenience of water-saving irrigation,the high cost of oxygenated irrigation and the frequency of irrigation,these two methods are not easy to popularize.Therefore,in 2022,this paper conducted a field experiment in Jinmei Agricultural Machinery Major,Changhu Village,Wuhan,Hubei Province,in order to explore a new type of soil aeration technology for paddy fields,so as to achieve CH4 emission reduction in paddy fields and rice yield increase.Four different gas concentration injection treatments per unit time were set in this experiment:0L/h（CK）,10L/h（O10）,15L/h（O15）and 20L/h（O20）.On the basis of O15treatment in each cell,four different daily gas injection duration treatments are set:The aim of this study was to explore the mechanism of deep aeration cultivation technology in paddy field to reduce methane emission and the effect of this technology on emission reduction and yield increase,including 0 h,3 h,6 h and 10 h daily gas injection.The main research results are as follows:1.Deep-layer aerated cultivation technology in paddy field has the potential to reduce CH4 emission in paddy field,which is mainly manifested in that the technology can effectively reduce the CH4 concentration in paddy field soil profile.At 10 cm of soil profile,the CH4 concentration of O10,O15 and O20 treatments decreased by 34.73%,40.61%and47.48%,respectively,compared with CK treatment.At 20 cm of soil profile,the CH4concentration of O10,O15 and O20 treatments decreased by 34.41%,42.50%and 48.33%compared with CK treatment,respectively.At 30 cm soil profile,the CH4 concentration of O10,O15 and O20 treatments decreased by 34.40%,42.49%and 48.10%compared with CK treatment,respectively.At the soil profile of 40 cm,the CH4 concentration of O10,O15 and O20 treatments decreased by 12.81%,21.71%and 28.63%,respectively,compared with CK treatment.At 50 cm soil profile,deep aeration cultivation in paddy field had no effect on CH4 concentration.2.Using 13C pulse labeling technology,this study proved that deep aeration cultivation technology in paddy field promoted the oxidation of CH4 by reducing the abundance of methanogens and increasing the abundance of methanogens,thus achieving the emission reduction of CH4.Compared with CK treatment,O10,O15 and O20treatments reduced the abundance of methanogens by 4.68%-22.11%,16.60%-38.04%and38.30%-57.20%,respectively.The abundance of methane oxidizing bacteria was increased by 30.94%-59.40%,41.49%-120.00%and 55.67-185.46%.With the increase of gas injection per unit time,13CH4 emission fluxes of O10,O15 and O20 treatments decreased by 27.31%-53.94%compared with CK treatments.3.The maximum influence radius of the deep aeration cultivation technique on the reduction of CH4 row in paddy field is between 14-16 m.When the pulse radius is more than 16 m,there is no significant difference in cumulative CH4 emissions under different daily gas injection duration.In the range of 0-16 m pulse radius,CH4 emissions at 3 h,6 h and 10 h were significantly reduced by 19.67%,26.37%and 30.64%compared with 0 h treatment.4.Deep aeration cultivation technology in paddy field promoted the growth and development of root system.In tillering stage,compared with 0 h treatment,root surface area,root length and root volume of 3 h treatment increased by 9.69%,35.07%and 32.89%,respectively.Root surface area,root length and root volume increased by 22.47%,44.80%and 48.68%,respectively.Root surface area,root length and root volume increased by45.81%,56.26%and 80.26%after 10 h treatment,respectively.At booting stage,compared with 0 h treatment,root surface area,root length and root volume of 3 h treatment increased by 16.40%,17.00%and 15.98%,respectively.Root surface area,root length and root volume increased by 28.70%and 28.01%,respectively,after 6h treatment.Root surface area,root length and root volume increased by 41.75%,43.20%and 34.99%after 10 h treatment,respectively.5.Deep aeration cultivation technology in paddy field improved nitrogen utilization rate and rice yield.At the pulse radius of 4 m and 12 m,the nitrogen absorption efficiency of 3 h treatment was increased by 23.53%and 12.18%,respectively,compared with 0 h treatment.The nitrogen absorption efficiency of 6 h treatment increased by 35.34%and27.79%,respectively.The nitrogen absorption efficiency of 10 h treatment increased by49.37%and 39.27%,respectively.At the pulse radius of 4 m and 12 m,the yield of 3 h treatment was increased by 7.45%and 4.81%,respectively,compared with 0 h treatment.The yield of 6 h treatment increased by 16.74%and 13.35%,respectively.The yield of 10h treatment increased by 23.23%and 19.99%,respectively.In conclusion,compared with the traditional flooded paddy field model,the paddy field model using deep-aerated cultivation technology significantly reduces greenhouse gas emissions and improves rice yield. |
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