Effects Of Biochar And Biochar Compound Fertilizer Application On Crop Yield And Economic Benefits

The cereal and vegetable production in China is changed by two major issues in recent years.The first issue is the declining in soil fertility and quality;and the second one is that large amounts of crop straw are produced every year and these crop straws cannot be used effectively.The conversion of crop straw to biochar through pyrolysis under limited oxygen supply and then amend the biochar into agricultural field received great attention in the last decade.Biochar production could utilize crop straw effectively,and soil amendment also promotes soil carbon sequestration,reduces greenhouse gas emission,improves soil fertility and crop yields.Therefore,biochar production and soil amendment is becoming a potential way of utilizing crop straw.Although some studies have shown that biomass soil application has a broad prospect in soil carbon sequestration,soil improvement and crop yield,its economic feasibility is questioned.In this study,we firstly investigated the effect of raw biochar application on soil fertililt and crop yield in two field experiments and then accessed the effect of biochar compound fertilizer,which was produced by mixing biochar with chemical fertilizers,on rice and corn production.The economic benefits were evaluated finally for biochar alone and biochar fertilizer.And then the main findings are as follows:(1)In Artemisia selengensis experiment,biochar alone increased soil organic matter,total nitrogen,available phosphorus and available potassium significantly,but had no significant effect on soil pH and conductivity.Both biochar and organic fertilizers had no effect on the yield of Artemisia selengensis.In potato experiment,biochar addition increased soil pH,organic carbon,available phosphorus and available potassium significantly,and soil conductivity and C/N also increased under biochar soil amendment.Soil organic carbon increased by 68.1%and 171.9%under biochar application rate of 20 and 40 t·ha-1 respectively;soil available potassium were increased by 309.5%and 666.4%under biochar application rate of 20 and 40 t·ha-1;C/N increased by 69.9%and 142%under biochar application rate of 20 and 40 t·ha-1.Biochar amendment at 20 t·ha-1 increased potato yield by 41.1%;however,biochar at 40 t·ha-1 had no effect on potato yield.(2)Biochar was made into biochar compound fertilizer by mixing it with chemical fertilizer and then applied it into the field of corn and rice.Results showed that biochar based compound fertilizer significantly improved the yield of corn and rice.Under biochar based compound fertilizer,maize height,ear height,effective panicle length,100 grain weight,yield and biomass increased by 18.1%,26.1%,13.8%,7.3%,24.3%and 12.15%respectively.In addition,the number of empty particles,1000-grain weight and yield of rice under biochar based compound fertilizer were significantly different from those of conventional fertilization.The number of empty particles decreased by 46.8%and the grain weight increased by 9.42%.Com and rice yield increased by 12.15%and 8.14%respectively compared with traditional fertilization.In conclusion,biochar soil amendment can improve soil fertility while its effect on crop yield were influenced by crop types and biochar application rate.Biochar compound fertilizer could increased grain yield of corn and rice significantly compared with chemical compound fertilizers.In comparison with raw biochar amendment,biochar compound fertilizer application has higher economic benefits.