Abstract: Taking seven soybean genotypes differing in P efficiency as test materials, a pot experiment with acid soil was conducted to study the interactive effects of P deficiency and Al toxicity on the growth of the genotypes under liming and P fertilization. The results showed that P deficiency and Al toxicity were the limiting factors for the soybean growth on acid soil, and the impact of Al toxicity was more severe. There existed interactive effects between P deficiency and Al toxicity. Comparing with liming or P fertilization alone, their combination could greatly promote soybean growth. The impact of P deficiency and Al toxicity on the P uptake by soybean was far greater than that on N and K uptake. A reasonable planting system for soybean would be helpful for the amelioration of acid soil. The combined application of 1.103 g Ca(OH)₂·kg^-1soil and 2.018 g KH₂PO₄·kg^-1 soil) could increase the acid soil pH by 38.4% and the available P content by 3223.8%, and decreased the soil exchangeable Al content by 96.3%. Planting P-efficient soybean genotypes rather than P in-efficient soybean genotypes had better effect in acid soil amelioration.

Key words: soybean, P deficiency, Al toxicity, P efficiency, acid soil, near surface CO₂ concentration, character of underlying surface, monitoring along the transects, urbanization, Shanghai City.