Abstract
A field experiment was conducted on an acid-Al-toxic Umbric Dystrochrept soil to measure the effect of a single application of limestone and (or) farmyard manure (FYM) on crop yields, and the kinetics of soil acidity over three successive crops. The application of FYM alone increased the yield of the first crop of maize (Zea mays L.) to a similar extent as the application of 3 t limestone ha-1. The combination of FYM and 1 t limestone ha-1 gave consistently the highest yield from three consecutive crops of maize, soya bean [Glycine max (L.) Merrill], and maize on this Al-toxic soil. The periodic analysis of soil samples indicated that application of FYM initially decreased the exchangeable and soluble Al (0.01M CaCl2) without affecting soil pH, but the difference was eliminated with time. Limestone alone and in combination with FYM was also initially more effective in decreasing Al with an increase of soil pH and exchangeable Ca + Mg.
