Department of Physical Chemistry of Porous Materials, Institute of Agrophysics of Polish Academy of Sciences, Doswiadczalna 4 Str., 20-290 Lublin, Poland.
Molecules. 2022 Mar 31;27(7):2273. doi: 10.3390/molecules27072273.
Chitosan is becoming increasingly applied in agriculture, mostly as a powder, however little is known about its effect on soil mechanical properties. Uniaxial compression test was performed for cylindrical soil aggregates prepared from four soils of various properties (very acidic Podzol, acidic Arenosol, neutral Fluvisol and alkaline Umbrisol) containing different proportions of two kinds of chitosan (CS1 of higher molecular mass and lower deacetylation degree, and CS2 of lower molecular mass and higher deacetylation degree), pretreated with 1 and 10 wetting-drying cycles. In most cases increasing chitosan rates successively decreased the mechanical stability of soils that was accompanied by a tendential increase in soil porosity. In one case (Fluvisol treated with CS2) the porosity decreased and mechanical stability increased with increasing chitosan dose. The behavior of acidic soils (Podzol and Arenosol) treated with CS2, differed from the other soils: after an initial decrease, the strength of aggregates increased with increasing chitosan amendment, despite the porosity consequently decreasing. After 10 wetting-drying cycles, the strength of the aggregates of acidic soils appeared to increase while it decreased for neutral and alkaline soils. Possible mechanisms of soil-chitosan interactions affecting mechanical strength are discussed and linked with soil water stability and wettability.
壳聚糖在农业中的应用越来越广泛，主要以粉末形式存在，但人们对其对土壤机械性能的影响知之甚少。本研究采用单轴压缩试验对 4 种不同性质土壤（强酸性灰化土、酸性灰壤、中性冲积土和碱性暗棕壤）中的柱状土团聚体进行了研究，这些土壤中含有两种不同比例的壳聚糖（CS1 分子量较大、脱乙酰度较低，CS2 分子量较小、脱乙酰度较高）。土壤分别经过 1 次和 10 次干湿循环预处理。在大多数情况下，随着壳聚糖用量的增加，土壤的机械稳定性逐渐降低，同时土壤孔隙度呈增大趋势。在一个案例中（用 CS2 处理的冲积土），随着壳聚糖剂量的增加，土壤的孔隙度减小，机械稳定性增加。用 CS2 处理的酸性土壤（灰化土和灰壤）的行为与其他土壤不同：尽管随后孔隙度减小，但在最初降低后，随着壳聚糖添加量的增加，团聚体的强度增加。经过 10 次干湿循环后，酸性土壤的团聚体强度似乎增加，而中性和碱性土壤的团聚体强度则降低。讨论了影响机械强度的土壤-壳聚糖相互作用的可能机制，并将其与土壤水分稳定性和润湿性联系起来。
