Effect Of Aging Biochar On Organic Carbon Fractions And Carbon Emission Of Sandy Soil In The Arid Region

Biochar is a kind of highly aromatic refractory solid material prepared by slow pyrolysis of straw,rice husk and other agricultural and forestry wastes under anaerobic or anoxic conditions.Its properties are special,so it plays an important role in agriculture,climate,environment,materials and so on.After entering the soil,biochar is subjected to physical,chemical and biological effects and aging occurs,resulting in changes in its properties and further affecting the environmental efficacy of biochar.This research object of this study is sandy soil in Xinjiang,using the previous experimental study biochar positioning platform.The study area in the Shihezi 121st group,Xinjiang,compared with fertilization of chemical fertilizer(T0),explores a exert 15.75 t·hm^-2(T1),31.50 t·hm^-2(T2),63.00 t·hm^-2(T3)and 126.00t·hm^-2(T4)after 5 years of biochar application on sandy soil organic carbon composition and carbon emissions,the effect of combined with indoor simulation training test at the same time.To reveal the aging properties of biochar and its impact on soil organic carbon components and soil carbon emissions,to explore the carbon sequestration and emission reduction effects of biochar improved sandy soil,and to accurately evaluate the long-term ecological benefits of biochar fertilized soil.The major conclusions of the study are as follows:(1)After 5 years of biochar application,the alkali-hydrolyzed nitrogen in each treatment increased compared with the control,the contents of available phosphorus and available potassium increased with the increase of biochar application;soil bulk density and soil conductivity of each treatments decreased with the increase of biochar application.The biochar significantly increased the soil SOC content,increased the soil MBC and ROC content to enhance the soil carbon pool,which had no significant effect on the soil DOC content.Soil URE and SUC activity were proportional to the amount of biochar applied,and biochar reduced soil CAT activity.Soil SUC?URE activity was significantly correlated with soil ROC content.(2)After 5 years of biochar application,the soil CO₂ emission rate was proportional to the amount of biochar applied.There was a significant correlation between soil CO₂emission rate and soil temperature of5,10,15 cm,and soil respiration temperature sensitivity coefficient was also proportional to biochar application;there was no significant correlation between soil CO₂emission rate and soil water content.(3)The content of C and O elements and atomic ratio of 20%HNO₃/H₂SO₄oxidized biochar were closest to those of biochar after 5 years of natural aging in the field.The surface of fresh biochar is smooth and some new holes appear;the surface of aged biochar is rough and attached to some small particles,some holes are blocked;with the increase of HNO₃/H₂SO₄and H₂O₂concentration,the more serious the surface fragmentation of biochar,the more flocculants appear.(4)The CO₂ emission rates of acidification treated biochar and hydrogen peroxide treated biochar were higher than those of fresh biochar treatment and control(CK)treatment.Compared with CK treatment,the aging biochar significantly increased the soil SOC content,and the soil SOC content was proportional to the aging degree of biochar.The increase of soil SOC content in 40%HNO₃/H₂SO₄treatment and 30%H₂O₂treatment was the largest in different aging biochar treatment.Therefore,the aging biochar can promote the soil CO₂ emission rate of sandy soil in oasis farmland and increase the soil organic carbon content.20%HNO₃/H₂SO₄oxidized biochar can simulate the biochar after 5 years of natural aging in the field.