Adamczuk Agnieszka, Kercheva Milena, Hristova Mariana, Jozefaciuk Grzegorz
Department of Physical Chemistry of Porous Materials, Institute of Agrophysics of Polish Academy of Sciences, 20-290 Lublin, Poland.
Department of Physics, Erosion, Soil Biota, Institute of Soil Science, Agrotechnologies and Plant Protection "N. Poushkarov", 1331 Sofia, Bulgaria.
Materials (Basel). 2021 Dec 14;14(24):7724. doi: 10.3390/ma14247724.
Chitosan has become increasingly applied in agriculture worldwide, thus entering the soil environment. We hypothesized that chitosan should affect the water stability of soil. Since this problem has not been studied to date, we examined, for the first time, the influence of chitosan on the water stability and wettability of soil aggregates. The aggregates were prepared from four soils with various properties amended with different amounts of two kinds of powdered chitosan, and subjected to 1 and/or 10 wetting-drying cycles. The water stability was measured by monitoring air bubbling after aggregate immersion in water, and the wettability was measured by a water drop penetration test. The biopolymer with a lower molecular mass, lower viscosity, and higher degree of deacetylation was more effective in increasing the water stability of the soil than the biopolymer with a higher molecular mass, higher viscosity, and lower deacetylation degree. After a single wetting-drying cycle, the water stability of the soil aggregates containing chitosan with a higher molecular mass was generally lower than that of the soil; after ten wetting-drying cycles, the water stability increased 1.5 to 20 times depending on the soil. The addition of low-molecular-mass chitosan after a single wetting-drying cycle caused the water stability to become one to two hundred times higher than that of the soil. A trial to find out which soil properties (pH, C and N content, bulk density, porosity, and particle size distribution) are responsible for the effectiveness of chitosan action was not successful, and this will be the objective of further studies.
壳聚糖在全球农业中的应用日益广泛，从而进入土壤环境。我们推测壳聚糖会影响土壤的水稳定性。由于该问题迄今为止尚未得到研究，我们首次研究了壳聚糖对土壤团聚体水稳定性和润湿性的影响。团聚体由四种性质各异的土壤制备而成，添加了不同量的两种粉末状壳聚糖，并进行1次和/或10次干湿循环。通过监测团聚体浸入水中后的气泡情况来测量水稳定性，通过水滴渗透试验来测量润湿性。与分子质量较高、粘度较高且脱乙酰度较低的生物聚合物相比，分子质量较低、粘度较低且脱乙酰度较高的生物聚合物在提高土壤水稳定性方面更有效。经过一次干湿循环后，含有较高分子质量壳聚糖的土壤团聚体的水稳定性通常低于土壤；经过十次干湿循环后，水稳定性根据土壤不同提高了1.5至20倍。在一次干湿循环后添加低分子质量壳聚糖，会使水稳定性比土壤高出一至两百倍。试图找出哪些土壤性质（pH值、碳和氮含量、容重、孔隙率和粒径分布）对壳聚糖作用效果起作用的试验未成功，这将是进一步研究的目标。
