Effects Of Fenlong Tillage Combined With Nitrogen Reduction Fertilization On Microbial Community And Greenhouse Gas Emission In Cassava Soil

Fenlong tillage(FL)has been widely proved that the application can effectively improve crop yield.It has become an important research topic to investigate the environmental effects of FL and related fertilization methods.This study in south China 205 as test material,the use of FL and conventional tillage(CT)soil preparation,set up four different n application levels and two fertilizer,fertilizer for the first time to cassava(Manihot esculenta Crantz)harvest after taking soil greenhouse gas and soil samples,the FL combined with the reduction of nitrogen fertilization on cassava microbial community,the influence of greenhouse gas emissions and cassava yield.In the second year,the effects of FL on cassava yield and greenhouse gas emission from cassava land were observed.The test results show that:(1)Compared with CT,FL effectively reduced soil temperature by 1.35?,and the bulk density and porosity in the 21-30cm soil layer were smaller and larger.The nitrate N,available K,available P and p H of soil under FL were significantly higher than those under CT.(2)Soil urease,catalase,nitrite reductase and nitrate reductase activities were all affected by tillage methods and nitrogen reduction treatments.Under FL,the soil urease activity was the highest under conventional N application,and the soil catalase activity was the highest under 25%N reduction.Under CT,soil nitrite reductase activity was the highest under 25%N reduction,and the highest under 50%N reduction.(3)Under conventional N application and 50%N reduction treatments,the?diversity of soil microbial community was most closely related to the physical and chemical properties of soil,and was significantly positively correlated with soil urease,organic matter,MBC,MBN and other physical and chemical properties.Compared with CT,increasing nitrogen fertilizer under FL increased the relative richness of aerobic bacteria Firmicutes,and also increased the relative richness of fungi Carniophyta and Microphylococcus,which are closely related to soil organic matter,as well as the relative richness of bacteria Actinobacteria and Proteobacteria.(4)Soil CO₂,N₂O cumulative emissions,global warming potential(GWP),greenhouse gas intensity(GHGI)and soil carbon sequestration were all affected by tillage and nitrogen reduction treatments and their interactions.Tillage methods are the main factors affecting soil CH₄ cumulative emissions,GWP,GHGI and soil carbon sequestration.Compared with the FL,the soil CO₂ and N₂O cumulative emissions under CT and nitrogen application were the highest.The cumulative emissions of CH₄ and N₂O were the least under the FL without nitrogen fertilizer.The soil GWP and GHGI of 100%N under CT were 1170CO₂eq.kg·ha^-1 and 0.069 CO₂eq.Kg·kg^-1,respectively,which were significantly higher than those under each N reduction treatment.However,the GWP and GHGI of 100%N in FL were 367.6CO₂eq.kg·ha^-1 and 0.014CO₂eq.kg·kg^-1,respectively,which were not significantly different from those of the nitrogen reduction treatments.Under the same nitrogen application level,the soil carbon sequestration in the FL plot was significantly higher than that in the CT plot,and the soil carbon sequestration in the 100%N plot was the highest,which was 1.95kg·ha^-1·a^-1.The effect of delayed FL on soil greenhouse gas emission lasted to the second year,and the soil GWP and GHGI were significantly lower than those of CT plots in two years.(5)The tillage method was the main factor affecting the yield of cassava:the average two-year yield of cassava under FL was 28.2%-36.6%higher than that under CT.The effect of the late tillage on the yield of the FL lasted until the second year,the cassava yield was still increased by 25.0%-32.2%compared with that of the plots under CT.