Effects Of Vermiculite Modification On Rice Straw Biochar Stability

The high stability of biochar is the key factor for its wide application in the field of agricultural environment.Mineral modification treatment can regulate the stability of biochar,However,there are few related studies at present,and the corresponding regulation mechanism is not very clear.In this paper,a series of biochar were prepared from rice straw under different carbonation temperature and vermiculite modification conditions.The stability of biochar was comprehensively evaluated by H/C atomic ratio,thermal stability,carbon oxidation loss rate,and carbon retention rate.The short-term degradation of rice straw biochar and vermiculite modified rice straw biochar in red soil and paddy soil was studied by laboratory culture experiments.The following conclusions were reached:(1)The increase of carbonization temperature increased the rice straw biochar pH(5.56 ~ 10.5),the degree of aromatization and thermogravimetric analysis remaining quality(24.6% ~ 67.2%),reduced the biochar carbon retention rate(75.6% ~ 51.9%)and carbon oxidation loss rate(51.8% ~ 2.43%)and H/C atomic ratio(1.36 ~ 0.60),increased the amount of mineral elements,reduced the number of oxygen containing functional groups(2)Soil type has more influence on soil C change and soil H/C change than water condition;The influence of water condition on the change of H/C in paddy soil is greater than that in red soil.The variation of soil C and soil H/C in arid red soil and flooded red soil was relatively large,indicating that rice straw biochar and vermiculite modified rice straw biochar prepared at different temperatures were more stable than rice soil in red soil.