不同热解温度棉秆生物炭对土壤持水性能的影响与模型适用性评价

Effects of Cotton Stalk Biochar Prepared at Different Pyrolysis Temperatures on Soil Water Retention and Evaluation of Model Applicability

摘要:

生物炭因其发达的孔隙结构和丰富的表面官能团,能有效改善土壤水力特性。将难以生化降解的棉秆转化为生物炭并用于土壤改良,是实现农业废弃物资源化利用与生态修复协同发展的可行途径。本研究以棉花秸秆为原料,在不同热解温度(300、400、500、600、700℃)下制备生物炭,系统表征棉秆生物炭孔隙结构、比表面积、官能团 演变及晶体结构的变化,并通过一维土柱模拟试验,定量研究不同热解温度棉秆生物炭及其施用量(1. 0% 、1. 5% 、 2. 0% )对土壤湿润锋迁移、水分入渗与蒸发过程的影响。采用Philip和Kostiakov模型对土壤入渗速率与时间的关系进行拟合,以再现水分入渗动态;同时,通过应用Rose和Gardner模型对土壤水分蒸发过程进行数值模拟。热解制备生物炭试验结果显示,随着热解温度升高,生物炭孔隙结构趋于规整有序,500℃条件下制备的生物炭比表面积和总孔容最大,分别为1. 67 m2 / g 和0. 003 2 cm3 / g,微介孔结构发达,芳香化程度较高,在土壤中稳定性较好。土柱模拟试验结果表明,棉秆生物炭通过毛细阻滞与孔隙重构作用显著延缓湿润锋迁移,降低入渗速率,抑制水分蒸发,提升土壤持水性能。其中,热解温度为500℃的棉秆生物炭施用量为2. 0% 时处理效果最优,较对照组水分入渗时间延长78. 6% ,累积入渗量提高12. 9% ,土壤蒸发量减少34. 0% 。模型拟合结果显示,Kostiakov 模型对入渗过程拟合精度高(R2 > 0. 99),优于Philip模型;Rose模型对蒸发过程模拟更准确(R2 > 0. 99),优于Gardner模型。综上,在适宜热解温度与施用量下,棉秆生物炭可同步优化土壤水分入渗与持留性能,为生物炭提升土壤持水能力提供理论依据。

Abstract:

Biochar is regarded as a promising material for improving soil hydraulic properties due to its porous structure and abundant surface functional groups. Cotton stalk, characterized by its rigid texture and high lignin content, is difficult to degrade effectively through conventional biochemical pathways. Converting it into biochar for soil amendment represents a viable strategy for synergizing agricultural waste recycling with ecological restoration. Biochar was produced from cotton stalks at different pyrolysis temperatures ( 300℃, 400℃, 500℃, 600℃and 700℃). The structural properties of biochar, including pore architecture, specific surface area, functional group evolution, and crystalline structure, were systematically characterized. Laboratory-based one-dimensional soil column experiments were conducted to quantitatively evaluate the effects of biochar produced at different temperatures and application rates (1. 0% , 1. 5% , and 2. 0% ) on soil wetting front migration, water infiltration, and evaporation processes. The Philip and Kostiakov models were applied to describe the relationship between infiltration rate and time, thereby simulating water infiltration behavior. Similarly, the Rose and Gardner models were used to numerically simulate soil water evaporation patterns. The results indicated that biochar produced at 500℃exhibited the highest specific surface area (1. 67 m2 / g) and total pore volume (0. 003 2 cm3 / g ), with well-developed micro- and mesoporous structures and a high degree of aromatization. Soil column experiments demonstrated that biochar application significantly delayed wetting front movement, reduced infiltration rate, suppressed evaporation, and enhanced water retention capacity, primarily through capillary blocking and pore structure reorganization. Among all treatments, the application of 2. 0% biochar produced at 500℃yielded the most favorable outcomes, exhibiting a 78. 6% prolongation of infiltration time, a 12. 9% increase in cumulative infiltration, and a 34. 0% reduction in evaporation compared with that of the control group. Model fitting showed that the Kostiakov model described the infiltration process with high accuracy (R2 > 0. 99), outperforming the Philip model, while the Rose model simulated evaporation more accurately (R2 > 0. 99) than the Gardner model. In conclusion, cotton stalk biochar produced at appropriate pyrolysis temperatures and application rates can significantly enhance soil water movement and retention. However, practical application for improving soil water retention should consider the native physicochemical properties of soil to select biochar produced under suitable pyrolysis conditions.