Effects of biochar on soil nutrient and carbon mineralization in tobacco-planting soil
[Objective]This study aims to investigate the effects and mechanisms of biochar with different particle sizes on soil nutrients and carbon mineralization in acidic and alkaline soils,so as to provide a theoretical basis for improving tobacco planting soils and reducing greenhouse gas emissions.[Methods]An indoor incubation test was conducted with six treatments:no biochar(HB0),20 mesh(HB20)and 100 mesh(HB100)biochar in Henan alkaline soil,and no biochar(CB0),20 mesh(CB20)and 100 mesh biochar(CB100)in Chongqing acidic soil.[Results](1)After 7 and 28 days of incubation,the content of available phosphorus,total nitrogen and organic carbon in the two types of soil was significantly increased by adding 100 mesh biochar compared with no biochar treatment.Biochar and soil types had a significant interaction effect on the content of available potassium.After 28 days and 102 days of incubation,the CB100 treatment significantly reduced soil ammonium nitrogen content by 35.29%and 22.53%compared with CB0,respectively.(2)The HB100 treatment significantly increased the total CO2 emissions by 29.93%compared with HB0,while the CB100 significantly reduced the total CO2 emissions by 22.22%compared with CB0.(3)Path analysis indicated that soil available phosphorus and water-soluble organic carbon content had a significant direct positive effect on CO2 emission rate in alkaline soil,while soil pH,available potassium,and ammonium nitrogen content had a significant direct negative effect on CO2 emission rate in acidic soil.[Conclusion]Adding biochar promotes carbon mineralization in alkaline soil from Henan but inhibits carbon mineralization in acidic soil from Chongqing,with the effect being more pronounced with smaller particle sizes of biochar.
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