有机质和粒径对中国4类典型土壤镁吸附量的影响

土壤是植物镁养分的主要来源,但我国南方地区土壤缺镁问题突出。本研究以中国4类典型土壤样品(赤红壤、砖红壤、黄棕壤和草甸土)为供试土壤,分别选用Langmuir、Temkin及Freundlich吸附等温模型拟合镁吸附试验,并进一步研究土壤有机质和粒径对镁吸附的影响。结果表明:1)Langmuir吸附等温模型有效拟合土壤镁吸附数据;2)加有机肥的土壤镁吸附量显著高于去有机质处理,1mm粒径的土壤镁吸附量显著高于2mm粒径土样;3)草甸土的镁吸附量最高,而砖红壤的镁吸附量最低;4)土壤的最大镁吸附量qmax与土壤pH、有机质、阳离子交换量、交换性镁离子具有极显著正相关(P0.01),与粉粒呈显著正相关(P0.05)。综上,土壤中施加有机肥及合理改善土壤颗粒组成结构均能显著增加土壤的镁吸附量。

Effects of organic matter and particle size on magnesium adsorption capacity of four types of soils in China

Soil is the main source of the magnesium nutrient for plants, however magnesium deficiency is wildly existing in soil in southern China. In this study, Langmuir, Temkin and Freundlich adsorption isotherm models are selected to simulate the result of magnesium adsorption experiments with four types of typical soil samples in China(red soil, latosol yellow brown and meadow soil), and the influence of organic matter and particle size on magnesium adsorption are further studied. The results show that: 1)The Langmuir adsorption isotherm model effectively fits the soil magnesium adsorption data; 2)The amount of magnesium adsorption in soil with organic matter is significantly higher than that of eliminating organic matter, and magnesium adsorption in soil with a particle size of 1 mm is significantly stronger than that of soil samples with a particle size of 2 mm. 3)Meadow soil and latosol have the highest and lowest magnesium adsorption capacity, respectively. 4)The maximal magnesium adsorption(qmax)has a very significant positive correlation with soil pH, organic matter, cation exchange capacity and exchangeable magnesium ions(P<0. 01), and a significant positive correlation with soil particle size(P<0. 05). In summary, increasing organic matter and reasonably improving soil particle composition can significantly increase the amount of magnesium adsorption in the soil.