Improving Effects of Different Calcium-Magnesium Conditioners on Latosol

At present, soil acidification seriously restricts the sustainable development of agricultural production. A common method that can be used to improve acidified soils is to apply calcareous materials (conditioners), but there is difference in the improvement effect of the conditioners on the same soil because of the conditioners containing different calcium-magnesium compounds. In order to find suitable conditioners for latosol (acidic red soil), two consecutive soil incubation experiments in laboratory have be done to study the improvement effects of different calcium-magnesium compounds on latosol. The results showed that: (1) Self-made conditioner (CM and it is composed of Mg(OH)₂, Ca(OH)₂, MgCl₂, CaCl₂,), CaO, CaCO₃ and Mg(OH)₂ could rapidly increase the pH and significantly reduce the content of potential acid in latosol. The soil exchangeable acid of Mg(OH)₂, CaCO₃, CaO and CM treatments than the treatment without conditioner (CK) were reduced by 88, 72, 66 and 34%, respectively, and the soil exchangeable aluminum decreased by 91, 80, 71 and 58%, respectively. (2) The calcium-magnesium compounds can significantly increase the contents of soluble and exchangeable calcium in soil compared with CK. CM and Mg(OH)₂ significantly increased the contents of soluble and exchangeable magnesium in latosol. (3) The soil pH buffer capacity of CM is significantly higher than those of other treatments as a result of it has the highest organic matter content and significantly increases the contents of exchangeable calcium and magnesium in the soil. But the soil pH buffer capacity of CaCO₃ and Mg(OH)₂ are significantly less than that of CK. Because the organic matter and organic acid of CaCO₃ and Mg(OH)₂ treatments are reduced by the soil pH of them increasing and the functional groups with pH buffer capacity on them may also be destroyed. So the paper suggests that improve acid latosol by applying conditioners with more soluble calcium and magnesium, Mg(OH)₂, which can effectively reduce acid ions in soil and improve the pH buffer capacity of soil.