| In order to research the influence of biochar application rates(0,20,40,60,80 t·hm-2)on soil greenhouse gases emissions,soil carbon and nitrogen and their fractions,soil temperature,soil moisture,soil aggregates,soil enzyme activity,crop yield and the correlation of soil physicochemical properties and soil greenhouse gases emissions,a field experiment was conducted using a pepper and winter wheat rotation system in loess soil,shaanxi province,China.The biochar used in this study was prepared by pyrolyzing apple tree branches at 450 ?.The main conclusions are as follows:1.Applying biochar effectively increased the total soil organic carbon(TOC),microbial biomass carbon and soil active organic carbon(AOC)and positively correlated with the biochar dosage.In 0-30 cm soil layer,the content of microbial biomass carbon increased by 7.63%-18.63%,18.69%-23.36%,23.01%-33.86% and 24.74%-47.05% respectively with the increase of biochar dosage.For AOC,it is high active organic carbon a simple structure organic carbon that biochar mainly increased.2.Biochar amendment increased the total soil nitrogen(TN),especially the content of 10-20 cm soil layer.The content of TN increased by 4.15%-21.89% with biochar amendment compared with the control.Biochar amendment significantly increased the content of NO3--N,NH4+-N and microbial biomass carbon and there was positively correlated between the three.For NO3--N,biochar treatments were significantly higher than control(B0)pre-transplant and positively correlated with biochar dosages.After fruit harvesting,B40 and B60 were significantly higher than control(B0)in 0-10 cm soil layer while all biochar treatments were significantly higher than control(B0)in 10-30 cm soil layer.Compared with the control,the content of NH4+-N increased by 4.61%-4.81%,8.29%-10.62%,16.81%-21.16% and 19.20%-33.22% respectively with the increase of biochar dosage during whole pepper growth season.3.Biochar amendment increased the temperature moderation capability of soil,improved the soil pH and increased the content of soil macro-aggregates,especially the content of >5 mm 5-2 and 1-0.5 mm.Compared with the control,the content of >5 mm 5-2 and 1-0.5 mm increased by 1.68-2.38,0.25-0.47 and 0.21-0.37 times.In 0-20 cm soil layer,the soil moisture in biochar treatments B20,B40,B60 and B80 were 11.57%-21.61%,11.44%-23.76%,11.38%-23.58% and 11.33%-24.34% and it is 6.21%-9.04% higher than that of control(B0).4.Biochar amendment increased CO2 emissions and CH4 uptake by 6.73%-23.35% and 3.62%-14.17% respectively and CO2 emissions was positively correlated with the biochar dosage.N2 O emissions and global warming potential(GWP)decreased at biochar rates of 20 and 40 t·hm-2 and increased when biochar levels were 60 and 80 t·hm-2compared with the control.5.The application of biochar significantly increased soil particulate organic carbon(POC)and positively correlated with the biochar dosage.WSOC decreased with the increase of the dosage of biochar.The contents of WSOC significantly decreased at biochar levels of 60 and 80 t·hm-2 and it decreased respectively by 21.82%-28.37%,35.88%-36.58% and 32.28%-44.07% in 0-10,10-20 and 20-30 cm soil layers compared to the control.6.Compared to the control(B0),ecosystem respiration(Re),soil respiration(Rs),plant respiration(Rp)were increased by 9.98%-27.57%,9.33%-19.47% and 10.18%-30.14% with biochar amendment,respectively.Rs were higher at biochar levels of 20 and 40 t·hm-2than that in the biochar levels of 60 and 80 t·hm-2while Re and Rp reached the maximum at 40 t·hm-2.7.Overall,soil enzyme activity had a tendency to reduce with the growth of pepper.In the same growth period of pepper,biochar application increased the invertase and urease activities while decreased the alkali phosphatease activities.Pepper and winter wheat yield increased by 2.7%-11.63% and 1.72%-32.19% respectively with biochar amendment and the production was the most significant at 40 t·hm-2 amount of biochar. |
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