两种温度制备生物质炭在榉树人工林土壤中的原位稳定性

In Situ Stability of Biochars Pyrolyzed at Two Different Temperatures in a Zelkova serrata Plantation Soil

研究生物质炭的稳定性是理解其土壤固碳功能的基础。以水稻为原料在两种温度(300℃和500℃)制备生物质炭,利用^(13)C稳定同位素技术,通过182 d的野外原位试验,比较两种生物质炭在榉树人工林土壤中的稳定性。整个培养期间,300℃和500℃生物质炭的累积分解量分别为10.5和3.65 g·m^(-2)。双指数模型拟合的结果显示,300℃和500℃生物质炭的难分解碳库的平均停留时间分别为99.8 a和302 a。300℃生物质炭的分解速率与土壤表层温度显著正相关(P=0.034,r=0.417,n=26),而500℃生物质炭的相关性不显著(P=0.549,r=0.123,n=26),表明土壤温度对生物质炭稳定性的影响因制备温度而异。野外原位试验表明500℃生物质炭具有更高的稳定性,为深入探讨生物质炭的稳定性提供了基础数据。

【Objective】The stability of biochar provides a basis for a better understanding of its potential to sequestrate soil carbon(C).This study aimed to study the stability of rice straw biochar in a Zelkova serrata plantation soil under in situ conditions and to explore the relationship between the stability of biochar,its chemical properties,soil temperature,and soil moisture content.【Method】Two biochars were produced by pyrolyzing rice straw at 300℃ and 500℃.By using^(13)C isotope,the stability of the biochars in soils was examined through 182 d in situ experiments in a Zelkova serrata plantation.【Result】The cumulative decomposition of 300℃ and 500℃biochars was 10.5 and 3.65 g·m^(-2),respectively,during the entire experiment.The results of double-exponential fitting indicated that the mean residence time of the recalcitrant C in 300℃ and 500℃ biochars were 99.8 a and 302 a,respectively.The decomposition rate of 300℃ biochar was significantly positively correlated with surface soil temperature(P=0.034,r=0.417,n=26)but not for 500℃ biochar(P=0.549,r=0.123,n=26).This indicated that the effect of soil temperature on biochar stability depends on its pyrolysis temperature.【Conclusion】To sum up,this study demonstrated that biochar produced at 500℃ is more stable than biochar produced at 300℃ through in situ experiments,and provides basic data for further study on biochar stability.