Response of five soybean (Glycine max (L.) Merr.) cultivars to lime and phosphorus on an acid Normandien subsoil

Abstract

Five soybean cultivars (Hill, Geduld, Forrest, Welkom and Oribi), previously selected for Al tolerance or sensitivity by a rapid seedling evaluation method, were grown in acid soil treated with varying rates of lime and P. After 35 days the plants were harvested and measurements of leaf area, shoot, root and nodule dry mass as well as elemental analysis were carried out. Lime had a significant effect on growth whilst P had relatively little effect. Classification for tolerance to soil acidity appeared to depend on the criterion used in the classification. Agreement with the ‘rag doll’-classification was obtained when comparing the cultivars, with respect to their relative shoot and leaf area yields, at the unlimed and first liming level. In the absence of lime the highest shoot yield occurred at the Intermediate level of P. Forrest appeared to perform consistently poorly in unlimed soils and could be classified as highly sensitive to acid soil infertility. However, it would be speculative lo classify the other cultivars into tolerant sensitive or intermediate groups. There was a strong indication that yield depressions in Forrest may not be attributed entirely to Al toxicity and that the relative balance of P, Fe and Cu may be involved Significant decreases in plant Al, Zn, Fe, Mn and Mg were observed with Increasing lime levels.