关键词: 土壤, 交换性镁含量, 土壤化学性质, 山西

Abstract: The exchangeable magnesium (Mg) contents in soils depended to a large degree upon the soil parent materials, soil physio-chemical properties, the climatic and other environmental conditions, and factitious factors. Using both field investigation and indoor analysis, the soils of 636 samples from the main types of farmland soils in Shanxi Province were sampled and analyzed to investigate the contents and distribution of exchangeable Mg and their relationship with the chemical properties of main types of farmland soils in Shanxi Province, China. The results indicated that the average content of exchangeable Mg in top soils (0-20 cm) of main types of farmland soils in Shanxi Province was 255.1 mg/kg, varied from 78.1 mg/kg to 641.8 mg/kg. 3.5% of exchangeable Mg contents in total soil samples were below 100 mg/kg, 85% of them were between 100 mg/kg and 400 mg/kg, and 11.5% of them were over 400 mg/kg. The exchangeable Mg contents in top soils varied obviously within different regions, the largest content was 378.5 mg/kg in the areas of Taiyuan City, and the lowest content was 144.2 mg/kg in the areas of Yangquan City. The contents of exchangeable Mg in soil profile (0-100 cm) varied from 78.1 mg/kg to 713.3 mg/kg. As a whole, the exchangeable Mg contents in soil profile had an increasing tendency with deepening of soil layers. The exchangeable Mg contents in the order from high to low in different types of soil were fluvo-aquic soil>cinnamon soil>chestnut-cinnamon soil>calcareous cinnamon soil>loessal soil>cinnamony soil. Correlation analysis between the exchangeable Mg contents and the chemical properties of main types of farmland soils revealed that there were significant positive linear relationships between exchangeable Mg contents and pH value, EC (electric conductivity) value, organic matter content, available nitrogen content in top soils, and the significant negative linear relationship between exchangeable Mg content and the ratio of K/Mg in top soils, as well as the significant curvilinear relationships between exchangeable Mg contents and total phosphorus content, available phosphorus content and available potassium content and ratio of Ca/Mg in top soils. This study demonstrated that the contents of exchangeable Mg are at high level in major farmland soils of Shanxi Province. The exchangeable Mg contents in top soils varied obviously within different types of soils and different regions. There are close relationships between the exchangeable Mg contents in top soils and chemical properties of the major types of farmland soils in Shanxi Province.

Key words: soil, exchangeable magnesium content, soil chemical properties, Shanxi Province