Response Of Soil Active Carbon Pool And Carbon Source Greenhouse Gases To Different Drip Fertilization Modes

In order to obtain the supply mode of drip irrigation water and fertilizer for increasing sugarcane yield,sugar content and reducing greenhouse gas emission,the effects of different drip irrigation and fertilization modes on soil methane（CH₄）and carbon dioxide（CO₂）emissions flux,soil organic carbon its fractions and enzyme activities,and sugarcane growth,yield and sugar content using field experiments were investigated,and then analyzed the relationships between them.The results show as follows,（1）Under drip irrigation condition,sugarcane yield(124 t hm^-2)and sugar yield(19.66 t hm^-2)in W₃₀₀F₁₂₀ treatment(irrigation volume:180 m³·hm^-2,fertilization rate:commercial organic fertilizer 15000 kg hm^-2,N 300 kg hm^-2,P₂O₅ 180 kg hm^-2,K₂O 240 kg hm^-2)were the highest.In addition,W₂DF₁₂₀treatment(Soil moisture:70%～80%θ_f（field water holding capacity）at seedling stage and mature stage,80%～90%θ_f at tillering stage and elongation stage;Fertilization amount:commercial organic fertilizer 15000 kg hm^-2,cow dung7500 kg hm^-2,N 300 kg hm^-2,P₂O₅ 180 kg hm^-2,K₂O 240 kg hm^-2)was also the optimal supply mode of drip irrigation water and fertilizer for increasing sugarcane yield and sugar yield.（2）Compared with other treatments,W₃₀₀F₁₂₀ treatment had higher content of dissolved organic carbon（DOC）and activities of invertase,amylase and cellulose in soil,but lower CH₄ and CO₂ emissions.Soil microbial biomass carbon（MBC）and cellulase activities in W₂DF₁₂₀ treatment were higher than those of other treatments,while the soil CH₄ and CO₂ emission fluxes were relatively low.（3）Significant positive correlation was obtained between CH₄ emission flux from sugarcane field and DOC（r=0.381-0.438）.The total organic carbon in soil was significantly positively correlated with invertase activity（r=0.466）.The readily oxidizable organic carbon in soil was significantly positively correlated with the cellulase and invertase activities（r=0.374-0.617）.Significant positive correlations were found among soil MBC and the activities of invertase,cellulase and catalase（r=0.515-0.585）.Therefore,the W₃₀₀F₁₂₀ and W₂DF₁₂₀ treatments are a reasonable drip irrigation water and fertilizer supply model for increasing sugarcane production and reducing carbon source greenhouse gas emissions from sugarcane soil.