Effects of Snow Cover Change on the Content of Base Ions and Available Silicon and Aluminum of Black Soil in Northeast China

Abstract

[Objective] In order to investigate the seasonal changes of base ions and available silicon and aluminum contents of black soil in northeast China under the change of snow depth in winter. [Methods] The environmental factors (temperature and humidity, moisture content, pH, total organic carbon), base ions, available silicon and activated aluminum of black soil in northeast China farmland were measured in snow removal group (SR), snow reduction group (SL), natural snow control group (C) and snow enhancement group (SA) were determined by artificial control of snow depth. The change process of the content of base ions and available silicon and aluminum in soil and their response to soil environmental factors were analyzed. [Results] The decrease of snow depth weakened the heat preservation effect of snow on black soil under seasonal snow cover, and the temperature and humidity (unfrozen water content) of 0—30 cm soil decreased significantly, which reduced the HCO3- content carried by unfrozen water during water and salt migration. The average pH of the soil was affected by the HCO3- content by the changes of -0.06, -0.04, - 0.02, and 0.01, respectively. With the decrease of soil alkalinity, the substitution ability of low-priced cations to high-priced cations in soil colloidal adsorption potential was enhanced, which increased the contents of exchange monvalent cations (Na+, K+), and decreased the contents of exchange and carbonate bivalent cations (Ca2+, Mg2+). Carbonate bivalent cation and exchange Na+ had positive and negative effects on TOC content, respectively, and the mean total organic carbon (TOC) content increased by 0.87, 1.09, 1.32 and 1.48 g/kg with the decrease of snow depth, respectively. The interaction between base ions and soil pH and TOC resulted in the decrease of soil pH and TOC content under the condition of reduced snow depth, which had an indirect effect on soil available silicon and aluminum content. The decrease of TOC content weakened the soil retention of low-active aluminum humate (Al-HA), and the decrease of pH promoted the conversion of low-active aluminum to high-active exchange aluminum (Ex-Al) and monomer hydroxyl aluminum (Hy-Al), which increased the soil aluminum toxicity, and promoted the dissolution of available silicon, resulting in the loss of soil silicon. [Conclusion] The reduction of seasonal snow cover in the middle and high latitudes caused by climate warming will affect the material and energy distribution of the black soil in Northeast China in winter, and thus change the growth and development environment of crops in the growing season. This study provided a certain scientific basis to reveal the seasonal variation process of soil mineral elements in the black soil region in Northeast China in winter.

Keywords

• snow cover change
• farmland black soil
• base cations
• activated silicon
• active aluminum