Effects Of Straw And Biochar Returned To The Field On Soil Acidity And Labile Organic Carbon

As biological modifier and organic fertilizer source,straw and biochar have high direct or indirect value for soil remediation,soil fertility and crop production.In order to study the difference of the effect of straw and biochar returned to the field on soil amendment and enrichment efficiency,the straw and the biochar made from equal amount of straw as experimental material,based on the percolation pond microplot(2m~2)experiment of maize and peanut for 4 years was located in Institute of Plant Nutrition and Fertilizer,Shenyang Agricultural University.The treatments were designed as equal amount of NPK nutrients,including 6 treatments:were no fertilizer(CK),nitrogen,phosphorus and potassium(NPK),biochar(C),NPK with biochar(CNPK),straw(S),NPK with straw(SNPK).The research aimed to study the physicochemical mechanism of soil amendment and enrichment efficiency of straw and biochar by comparing the effects of biochar and straw returned to the field on soil acidity and labile organic carbon at the same NPK application rate,so as to provide a theoretical reference for the comprehensive utilization of agricultural straw resources.The main results are as follows:(1)The soil physical properties and nutrients were significantly affected by straw and biochar returned to the field.The application of biochar and straw significantly reduced soil bulk density,increased soil porosity,water content,field capacity and organic matter,and the effect of biochar increased the organic matter was significant better than that of straw.Test of maize,soil water content and nitrogen content in the application of biochar was significant higher than that in straw,soil field capacity and total K in the application of straw was more significant.(2)In the fourth year of the experiment,the application of biochar or straw enhanced soil pH,and decreased the content of exchangeable acid and exchangeable aluminum in soil,but the content of exchangeable H~+showed no significant difference among treatments.The test results show that C and S increased the soil pH of maize by 0.55 and 0.45 units,and the soil pH of peanut by 0.32 and 0.46 units compared to before the test(pH=6.05).The application of biochar and straw reduced the soil exchangeable acid by more than 25%compared to no fertilizer control,but there was no significant difference between application of biochar and straw.At equal amount of straw and the same NPK nutrients,the effect of biochar increased the base-exchangeable ion and ECEC was significant better than that of straw.Test of maize,straw carbonization returning was more helpful to increase the soil pH.Test of peanut,the effect of biochar application on soil CEC was more significant.(3)The application of biochar and straw significantly increased soil organic carbon and labile organic carbon,and the effect of biochar to soil total organic carbon was more obvious,and the effect of straw to soil labile organic carbon was more significant.At the same NPK nutrients,the effect of biochar to the soil LROC of maize and peanut was significantly higher than that of straw returned to the field,the effect of straw returned to the field to the soil MROC of maize was significantly higher than that of biochar,and the effect of straw returned to the field to the soil HROC and MROC of peanut was significantly higher than that of biochar.The application of biochar and straw significantly increased soil carbon pool management index.At the same NPK nutrients,the soil CMI of maize increased by 51.17 and 54.47 units,and the soil CMI of peanut increased by 68.61 and 89.59 units compared to before the test.The correlation analysis showed that there was significant correlation between organic carbon and labile organic carbon,labile organic carbon and its components.And there was significant correlation between soil organic carbon,labile organic carbon and CEC,ECEC,base-exchangeable ion.(4)Straw and biochar have different effects on crop growth and yield.At the same NPK nutrients,the yield of maize and peanut could be increased by single chemical fertilizer and biochar,straw combined with fertilizer,but there was no significant difference in yield of three.The yield of maize was highest by CNPK,up to 12458.36 kg/hm~2,and the yield of peanut was highest by NPK,up to 6051.36 kg/hm~2.C and S had no significant effect on yield of maize and peanut.C and S can increase the chlorophyll CCI of peanut leaves,main stem height of peanut and plant height of maize.The effect of biochar increased the plant height of maize and chlorophyll CCI of peanut leaves was significant better than that of straw,and there was no significant difference in the effect of main stem height of peanut between biochar and straw.At the same NPK nutrients,the effect of biochar increased the chlorophyll CCI of maize and peanut leaves was significant better than that of straw.