Effect of Al2(SO4)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 Al2(SO4)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 Al2(SO4)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 O-P forms of 0.4% were the highest. When certain amount of P was applied, total inorganic P, Ca2-P, O-P, and Ca10-P had the trend of downward with the increase of Al2(SO4)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 Al2(SO4)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 Al2(SO4)3 was 0.3%∼0.4% of the weight of soils.