Effect of Al_2(SO_4)_3 improver on Phosphorus Forms and Phosphorus Adsorption in Soda Saline-alkali Soil

摘要

Soil indoors model experiments were carried out to study effects of Al_2(SO_4)_3 on P forms and P adsorption of Soda saline-alkali soils. Available P and P fractions as well as P adsorption of the soils were analyzed. The results showed that available P tended to decrease with the amount of Al_2(S0_4)_3 increasing. When P was not applied, on average, among the inorganic P, the percentage of Ca-P was the greatest, followed by O-P, Al-P and Fe-P. By contrast, both % and contents of 0-P forms of 0.4% were the highest. When certain amount of P w as applied, total inorganic P, Ca_2-P, O-P, and Ca10-P had the trend of downward with the increase of Al_2(SO_4)_3.The results of phosphate adsorption showed that the adsorption isotherms were fitted well with Langmuir equation. According to the Langmuir equation, when c/x/m is plotted against C, from the figure that there are two kinds of straight lines. One is straight line without break point (0%～0.6%), and the other is straight line with a break point (NPA-0%～NPA-0.6%), indicating that the presence of two energy absorption points that have a differing affinity. Taken together, The results suggest that though Al_2(SO_4)_3 can improve physical and chemical properties of soils, they had an effect on available P and P forms as well as P adsorption, and the optimal amount of Al_2(SO_4)_3 was 0.3%-0.4% of the weight of soils.