The effect of different organic materials on the alleviation of Al toxicity in soybean on a red-yellow podzolic soil

Abstract

A greenhouse pot experiment was conducted to investigate the effects of six organic materials on the growth of soybean (Glycine max (L). Merr.) cv. Wilis resulting from the alleviation of aluminium (Al) toxicity on a red-yellow podzolic soil [pH (H2O) 4.5; exchangeable Al 8.9 cmolc kg-1] from Kentrong, West Java. Each organic material was applied at three rates (0, 10 and 20 t ha-1) and all treatments received a basal fertiliser dressing consisting of N, P, K, Ca, Zn, Cu and Mo. When applied at 10 t ha-1, all organic materials increased whole plant dry weight by from 14 to 60%. The order of magnitude of this response was soybean tops < Calopogonium leaves < Leucaena leaves < rice straw < sugarcane leaves < Imperata tops. Increasing the organic materials rate to 20 t ha-1 increased whole plant dry matter yield for Imperata tops, Calopogonium leaves, soybean tops and Leucaena leaves, relative to yield with 10 t ha-1, had no effect for rice straw, and decreased dry matter yield for sugarcane leaves. Responses obtained to organic material applications, and differences among sources, were substantially related to their effects on monomeric Al (Almono) concentrations in the soil solution. No substantial changes in total Al concentration in the soil solution (AlT) were observed with application of the organic materials. The three leguminous materials strongly depressed monomeric Al concentrations in the soil solution, whereas the three non-leguminous materials only produced moderate depression.