College of Water Conservancy and Civil Engineering,Northeast Agricultural University
The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
东北地区是我国积雪分布范围最大的积雪稳定区,气候变暖对积雪沉积深度的改变可能对冬季东北黑土区土壤的冻结状态构成影响,使土壤理化环境进一步发生变化,从而改变生长季节土壤盐基离子及有效硅铝对作物的有效性。为探究冬季积雪深度变化下东北农田黑土盐基离子及有效硅铝的季节性含量变化特征,研究采用人工控制积雪深度的方法,通过测定除雪处理组(SR)、减雪处理组(SL)、自然积雪对照组(C)、增雪处理组(SA)的东北农田黑土环境因子(温湿度、含水率、pH值、总有机碳)、盐基离子、有效硅以及活性铝,分析土壤盐基离子及有效硅铝的含量变化过程,以及两者对土壤环境因子的响应关系。研究结果表明,积雪深度的降低改变了季节性雪被覆盖下黑土的水热分布状态,使0-30cm土壤温度显著下降,而土壤平均含水率则呈现出增长趋势。积雪深度降低引起的HCO3-含量减小使各组土壤平均pH值分别变化-0.06、-0.04、-0.02、0.01,土壤的碱性降低使得交换态一价阳离子(Na+、K+)含量升高,同时使交换态及碳酸盐态二价阳离子(Ca2+、Mg2+)含量降低。碳酸盐态二价阳离子与交换态Na+分别对TOC含量构成正向和负向的影响,使土壤平均总有机碳(TOC)含量随积雪深度的降低分别增长0.87 g/kg、1.09 g/kg、1.32 g/kg、1.48 g/kg。盐基离子与土壤pH、TOC的相互影响关系使在积雪深度降低的条件下土壤pH值与有机质含量降低,造成土壤对有效硅的吸附量降低,同时促进低活性铝向高活性铝转化,最终使土壤有效硅与腐殖酸铝(Al-HA)的含量显著减少,而交换态铝(Ex-Al)、单聚体羟基铝(Hy-Al)与酸溶无机铝(Col-Al)含量显著升高,盐基离子通过与TOC及pH的相互作用关系间接对有效硅铝构成潜在影响。
Northeast China is the largest snow stabilization region in China. The change of snow deposition depth caused by climate warming may affect the frozen state of soil in the northeast black soil region in winter, and further change the physical and chemical environment of soil, so as to change the availability of soil base ions and available silicon and aluminum to crops in the growing season. In order to explore the seasonal variation characteristics of black soil base ions and available silicon and aluminum in northeast farmland under the change of snow depth in winter, the method of artificial snow depth control was adopted. By measuring the environmental factors (temperature and humidity, moisture content, pH value, total organic carbon), base ions, available silicon and active aluminum of the northeast farmland black soil in the snow removal group (SR), snow reduction group (SL), natural snow control group (C) and snow enhancement group (SA), the change process of the content of soil base ions and available silicon aluminum was analyzed. And their responses to soil environmental factors. The results showed that the decrease of snow depth changed the water and heat distribution of the black soil under seasonal snow cover, and the soil temperature of 0-30cm decreased significantly, while the average soil moisture content showed an increasing trend. With the decrease of HCO3- content caused by the decrease of snow cover depth, the average pH values of soil in each group changed by -0.06, -0.04, -0.02 and 0.01, respectively. The decrease of soil alkalescence increased the contents of exchangeable monovalent cations (Na+, K+), while decreased the contents of exchangeable and carbonate bivalent cations (Ca2+ and Mg2+). Carbonate divalent cation and exchange Na+ had positive and negative effects on TOC content, and the average total organic carbon (TOC) content increased by 0.87 g/kg, 1.09 g/kg, 1.32 g/kg and 1.48 g/kg with the decrease of snow cover depth, respectively. The interaction between base ions and soil pH and TOC reduces soil pH and organic matter content under the condition of reduced snow depth, resulting in the decrease of soil adsorption of available silicon, and promotes the conversion of low-active aluminum to high-active aluminum. Finally, the content of available silicon and aluminum humate (Al-HA) in soil is significantly reduced. The contents of exchange aluminum (Ex-Al), monomer hydroxy-Al (Hy-Al) and acid-soluble inorganic aluminum (Col-Al) increased significantly, and the base ions had a potential effect on the available silicon and aluminum indirectly through the interaction with TOC and pH.