Effects Of Exogenous Maize Straw Carbon On Soil Organic Carbon Priming Effect And Temperature Sensitivity

Soil organic carbon?SOC?is the basis of soil fertility,maintaining the stability of farmland productivity and agroecosystems,and has an important impact on climate change.As an important exogenous source of SOC,plant residues have a great influence on the accumulation and mineralization?priming effect?of SOC after they applied into soil,which is significantly affected by temperature and soil basic fertility.However,the current research on this aspect is still insufficient.Therefore,in order to explore the differences and relationships of SOC mineralization and temperature sensitivity in different fertility soils after exogenous maize straw carbon addition,based on the long-term experimental station of brown earth in Shenyang Agricultural University,this study carried on an indoor culture experiment using¹³C isotope method to investigate the mineralization characteristics,priming effect and soil respiration temperature sensitivity after ¹³C labeled maize straw addition in high and low fertilizer soils.Two culture temperatures were set: 25 ??optimum temperature for microbial growth?and 18 ??average temperature of crop growing season?.The results were as follows:?1?Adding maize straw carbon could significantly increase the mineralization rate of SOC,the mineralization rate of SOC with maize straw was 1.92-22.8 times of that without maize straw.The mineralization rate of high fertility SOC was 21.2%-92.1% higher than that of low fertility soil,and the temperature had significant impact on the mineralization of brown earth's organic carbon.In the early incubation stage?0-200 days?,the mineralization rates of brown earth's SOC,maize straw and native soil-carbon at 25 ? were higher than 18 ?.The later stage showed the opposite trend.There was the same trend on the mineralization rate of maize straw and the native soil-carbon,showing the treatment with maize straw was higher than that without maize straw,and these of high fertility soil was higher than these of low fertility soil.Meanwhile,the mineralization rate of SOC from maize straw and native soil at 25 ? was the maximum,which were 24.08 ?g g^-1 d-1and 0.18 ?g g^-1d^-1,respectively.?2?Increasing temperature could significantly increase the accumulated mineralization of SOC in brown earth.Under high temperature,the accumulated mineralization of SOC was2.1% 97.7% higher than that of low temperature incubation.The accumulated mineralization of SOC in high fertility brown earth was about 1.15 1.79 times of that in low fertility brown earth.Moreover,the accumulated mineralization of soil carbon with straw was about 10.6 31.5 times of that without straw.Among them,the highest accumulated mineralization of the high fertility soil was 2.56 mg g^-1 when it was cultured at 25 ? for 450 days.Under the condition of adding maize straw,the accumulated mineralization amount of carbon from maize straw and native soil was larger than that of the treatment without maize straw.The increase of temperature was promoted the accumulation of carbon mineralization of maize straw and native soil.The accumulated mineralization of carbon from maize straw and native soil in high fertility brown earth was higher than that in low fertility brown earth.The maximum values of carbon accumulation and mineralization from maize straw and soil were 44.03 mg^-1 and 0.49 mg^-1.?3?The priming effect of low fertility soil was higher than that of high fertility soil.Thecumulative priming effect of soil at 18 ? was higher than that at 25 ?.The highest positive priming effect of straw addition at 18 ? was 613.09%.During the incubation period,the lowest cumulative priming effect of low fertility SOC with maize straw was under 25 ? at450 days,with a number of 22737.8%.?4?The addition of maize straw carbon reduced the temperature sensitivity of SOC mineralization in both high and low fertility soils.While the temperature sensitivity of SOC mineralization in the native soil showed a significant variation,when the incubation day-140 and 300 were the important turning periods.The highest temperature sensitive coefficient of low fertility soil without maize straw was 2.65,while the lowest temperature sensitive coefficient of low fertility soil with maize straw was 0.39 at 300 days.