生物质炭对土壤物理性质影响的研究进展

生物质炭在农业与环境中的应用已成为近期国内外研究热点,有关生物质炭特性以及生物质炭对土壤化学、生物学性质和作物产量的影响,已经有一些综述,但是生物质炭对土壤物理性质影响的相关综述很少。本文对近10年生物质炭对土壤物理性质影响相关的研究成果进行了整理分析。研究结果发现生物质炭可以降低土壤容重,提高土壤团聚体稳定性,增加田间持水量和土壤有效水含量,降低饱和导水率等。生物质炭影响土壤物理性质的主要原因是生物质炭具有较大的比表面积和孔隙度。此外,生物质炭与土壤矿质颗粒结合,并通过对土壤微生物活性和植物生长的影响间接影响土壤物理性质。生物质炭对土壤物理性质的影响与多种因素有关,如生物质炭原料、裂解温度、施用量和颗粒大小,土壤质地和处理时间等。关于生物质炭对土壤物理性质影响的长期研究很少,且缺乏田间试验。因此,将来的研究应更加倾向于长期田间条件下生物质炭对土壤物理性质的影响,并逐渐发现生物质炭的作用机理,为实际的农业生产和生态治理提供科学依据。

Biochar effect on soil physical properties: A review

Biochar is charred biomass produced under limited or no oxygen (O₂) supply and at high temperature. Rich in aromatic carbon (C), biochar can persist in soil for hundreds or thousands years. Biochar application in agricultural soils has attracted an intensive global research with extensive reviews of biochar characteristics, effects on soil chemical, biological and physical properties and on crop growth. However, the work on the effect of biochar on soil physical properties is not as detailed as those on soil chemical and biological properties. In this study, relevant publications on the effect of biochar on soil physical properties in recent decades were searched and summarized. The results indicated that biochar application reduced soil bulk density, improved soil aggregate stability, field water holding capacity, soil available water content, and decreased saturated hydraulic conductivity through direct and indirect ways. Biochar has huge specific surface area and porosity, which directly influences soil physical properties such as reducing soil bulk density and increasing water holding capacity and soil available water content. Furthermore, biochar particles combine with soil minerals to change soil structure and create the proper environment for soil microbial and plant root growth, which ultimately affect soil physical properties. Indirectly, the effect of biochar on soil physical properties includes improved soil aggregate stability and saturated hydraulic conductivity. The effect of biochar on soil physical properties is related to biochar application rate, feedstock type, pyrolysis temperature, particle size, soil texture and duration in the soil. Generally, the higher the amount of biochar applied, the more significant are the induced changes in soil physical properties (bulk density, water holding capacity and saturated hydraulic conductivity). Woody biochar significantly increases saturated hydraulic conductivity, while grass biochar has no effect on saturated hydraulic conductivity. In addition, as the duration after biochar application increases, its effect on soil physical properties decreases. However, very limited studies have investigated this relationship under long-term filed conditions, and field experiments have been even relatively scarce. Consequently, the further studies should focus on the long-term effects of biochar application on soil physical properties in filed condition, and investigate the mechanisms behind the biochar effect on soil physical properties, which is essential to provide scientific evidence for the real agricultural production and ecological improvement. Furthermore, the relationships between biochar characteristics and soil physical properties are not fully known. Thus, there are needs to further investigate the effect of biochar application on the interaction of soil physical and chemical, biological properties and the mechanisms.