摘要:生物炭具有提高土壤肥力和减缓温室气体排放的作用，但其对土壤有机碳矿化的作用效应存在争议。以新疆灰漠土为研究对象，采用300℃和600℃制备的棉花秸秆炭（棉杆炭）为试材，在25℃、75%的土壤饱和含水量条件下，通过100 d的室内培养，研究了不同比例的棉杆炭添加（0、0.1%、0.5%、1.0%、2.0%和100%，以质量计）对土壤有机碳矿化的效应。结果表明：1）高温制备的棉杆炭，孔隙结构排列整齐，表面光滑，孔隙度和比表面积大，芳香化程度增强；2）棉杆炭的有机碳矿化速率与时间呈乘幂关系（P < 0.05），300℃棉杆炭相比600℃棉杆炭的累积矿化量和累积矿化率分别提高了318%和87.06%；高温炭化抑制了有机碳矿化；与对照相比，添加300℃棉杆炭增加了土壤有机碳累积矿化量（0.1%处理除外，降低了7.22%），并随棉杆炭添加量而增加，土壤有机碳累积矿化量提高幅度在3.05%-35.28%，而添加600℃棉杆炭降低了土壤有机碳累积矿化量，降低幅度为6.11%-10.79%；3）培养前期（0-20 d）300℃棉杆炭对灰漠土土壤原有有机碳矿化为正激发效应（0.1%处理除外），后期为负激发效应，整个培养期内为负激发效应；600℃棉杆炭培养前期（0-5 d）对土壤原有有机碳激发效应微小，主要表现为负激发效应。由此可见，低温制备的棉杆炭能提高土壤有机碳矿化，而高温制备棉杆炭则抑制了土壤有机碳矿化，棉杆炭添加对土壤原有有机碳矿化具有负激发效应，能够促进土壤有机碳积累。



Abstract:Biochar can improve soil fertility and reduce greenhouse gas emission, but its effect on soil organic carbon (SOC) mineralization is controversial. In this study, we used gray desert soil of Xinjiang as a case study and cotton stalk-char (BC) produced using cotton straw at 300℃ and 600℃ was used as a test material. Different proportions of BC were added to dry soil 0 (0BC), 0.1% (0.1%BC), 0.5% (0.5%BC), 1.0% (1.0%BC), 2.0% (2.0%BC), 100.0% (100%BC) (w/w), and then incubated at 25℃ under 75% saturated soil moisture condition for 100 d. The effects of BC on the SOC mineralization were evaluated. The results showed the following. 1) The BC with high temperature carbonization had smoother surface with neatly-arranged porous structure, the porosity and specific surface area increased, and the aromatization degree was enhanced. 2) A significant power function correlation was observed between the SOC mineralization rates over time (P < 0.05). Compared with the biochar produced at 600℃, the accumulated amount of mineralization and cumulative mineralization rate of SOC with biochar produced at 300℃ increased by 318% and 87.06% respectively. High temperature carbonization inhibits SOC mineralization. Except in the 0.1% BC treatment, the cumulative quantity of SOC mineralization with the addition of biochar produced at 300℃ increased by 3.05%-35.28% compared with that of the control treatments, and it increased with the content of BC added. On the contrary, the amount of accumulative SOC mineralization decreased by 6.11%-10.79% with the biochar produced at 600℃. 3) The positive priming effect during the early stage of incubation (0-20 d) on the native organic carbon mineralization of gray desert soil (except the 0.1% BC treatment). Whereas, the biochar produced at 300℃ showed negative priming effects during the late stage of incubation. However, it showed a negative priming effect throughout the incubation period. A similar trend was observed for the treatments with biochar produced at 600℃, and the positive priming effect was negligible during the early stage of incubation (0-5 d). Therefore, the biochar produced from cotton shell at low temperatures can enhance the SOC mineralization, whereas BC with high temperature carbonization inhibits SOC mineralization. The SOC accumulation can be increased with the addition of BC to soil due to negative priming effects.





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