Effects Of Organic Manure Substitution For Chemical Fertilizer On The Growth Of Double Cropping Rice And Greenhouse Gas Emission In Rice Field

In order to further explore the effect of organic manure instead of chemical fertilizer and straw returning on double-cropping rice yield,nutrient absorption and soil nutrient,and to simultaneously observe the greenhouse gas emissions from rice under the treatments of single application of chemical fertilizer and organic manure instead of chemical fertilizer,which in order to afford the technical support of the rational use of organic matter in double-season rice areas in anhui province jianghuai rice areas.The experiments were set with four treatments,including with no fertilization(CK),the application of chemical fertilizer only(F),the application of organic manure(FM),and chemical fertilizer with straw returning(FS).The yield,nutrient absorption,soil nutrients and greenhouse gas emissions of double-cropping rice under different treatments were observed respectively,and the following conclusions were drawn:(1)Compared with the F treatment,the FM treatment can increase rice yield,mainly in the late rice season.The yield of late rice increased by 1.76%and 9.79%in two consecutive years respectively,and the annual rice yield in 2018 year increased by 8.24%significantly.The rice yield was increased by 2.59%?10.11%in three consecutive seasons,except the first season,and reached significant differences in the next two seasons.(2)According to the average results of two years,compared with no fertilization,each fertilization treatments can increase the accumulative amount of nitrogen,phosphorus and potassium nutrients in both straw and grain of rice significantly.Compared with F,the annual average accumulation of nitrogen,phosphorus and potassium in the double-cropping rice system was increased by 1.85%,9.14%and 9.00%,respectively.The average annual accumulation of nitrogen,phosphorus and potassium nutrients in the overground of rice straw mulching increased by 0.78%,1.71%and 8.39%,respectively.(3)Compared with the F treatment,the FM treatment can increase the contents of soil organic matter,total nitrogen and available phosphorus by 3.79%,4.32%and 68.93%,respectively,among them,the available P content of FM increased significantly;For the treatment of FS,the content of soil organic matter and total nitrogen increased by 2.03%and 2.16%respectively,and the content of soil available phosphorus and available potassium increased by 57.77%and 17.31%respectively,both of which reached significant differences.The correlation between soil nutrient content and rice yield indicated that the yield of double-season rice and soil nutrient content have reached a significant(P<0.05)or extremely significant(P<0.01)positive correlation.The relationship between average yield and soil nutrients of late rice was the highest.(4)Compared with the F treatment,the cumulative annual emissions of CH4 increased by 7.67%and N2O decreased by 25.32%significantly.According to different periods,CH4 emission of the FM treatment increased by 11.8%and 3.5%in early rice season and in late rice season,respectively.Apply all organic manure in the early rice season can slow down the increase of CH4 emission in late rice season.The global warming potential is further utilized to measure the greenhouse effect of replacing chemical fertilizers with organic manures.The results showed that compared with the F treatment,the FM treatment increased the potential of rice field warming,but the annual yield increased by 7.10%and the greenhouse gas emission intensity decreased by 3.70%.