裂解温度对新疆棉秆生物炭物理化学性质的影响

Effect of Pyrolysis Temperature on Physicochemical Properties of Xinjiang Cotton-straw Biochar

生物质的裂解温度影响其所生产的生物炭炭的物理和化学性质,进而影响其田间应用效果。棉花秸秆是干旱区特别是新疆地区的主要农业生物质资源,其生物炭利用途径有望克服现有秸秆利用途径的不足,但对棉秆生物炭理化性质及其变化的认识还很缺乏。本文在不同的裂解温度下对新疆棉秆生物炭物理和化学性质进行研究,发现随着裂解温度的升高,生物炭的产率、阳离子交换量、O/C和H/C值降低,p H、电导和持水性能提高,Na+、K+趋势不明显,Cl-和SO2-4等盐碱化离子以及Ca^(2+)、Mg^(2+)营养元素含量随温度的升高降低;C、N、S、C/N和灰分等均提高,NH+4-N在550℃碳化条件下含量最高。因此在田间应用中,应针对土壤特点和解决的问题,调控碳化温度,从而达到趋利避害的目的。

Pyrolysis temperature exerts great influence on physicochemical properties of biochar pyrolysic products,further on their field applications. Generally,cotton stalks are main agricultural biomass resources in arid areas,especially in the Xinjiang Autonomous Region,China and the application of biochar can overcome the drawbacks of the current utilization of straw. However,knowledge on cotton biochar physicochemical properties and their variation were seldom reported. In this study,effects of various pyrolysis temperatures on physicochemical properties of Xinjiang cotton straw biochar were investigated. Results show that,with increasing pyrolysis temperature,all of the yield,cation exchange capacity（ CEC）,H / C,and O / C ratios of biochar decrease,whereas the p H,electrical conductivity and water holding capacity increase; there were neither significant positive nor negative correlations of Na＋and K＋contents with temperature,respectively,meanwhile,contents of saline ions such as Cl-and SO2-4,and nutritional elements such as Ca2＋and Mg2＋decrease with increasing pyrolysis temperature; while contents of carbon,nitrogen,sulfur,C / N ratio and ash increase with increasing pyrolysis temperature; the highest content of NH4＋-N was detected at B550. All of these results indicate that biochar pyrolysis temperature should be properly adjusted considering the characteristics of the soil.