Effect of rice-husk ash on exchange acidity, growth and yield of groundnut (Arachis hypogaea l.) in an acid ultisol.

Abstract

Response of groundnut grown on acidic soil to rice-husk ash applied at 0, 1, 2, 3 and 4 t ha-1 was studied in two field experiments in 2005 and 2006 at Ishiagu in the derived savanna zone of southeast Nigeria. Treatments were fitted in a randomized complete block design (RCBD) replicated three times. Effects of treatments on some soil fertility and productivity parameters were evaluated. The rice-husk ash used contain 64.00 g kg-1Ca, 12.20 g kg-1 Mg, 12.50 g kg-1 P, 9.00 g kg-1 K, 2.10 g kg-1 N, 1.23 g kg-1 organic carbon and had a pH of 10.86. Soil pH increased from initial values of 5.16 to 6.20, while levels of exchangeable acidity correspondingly decreased from initial values of 0.80 to 0.26 cmol kg-1 with 3 t ha-1 applied rice-husk ash. Estimation of linear and quadratic curves respectively for soil pH and exchange acidity show values of r2 = 0.95 for soil pH and R2 = 0.98 for exchange acidity. Significant increases (P < 0.01) in soil P, K and Ca status relate significantly (P = 0.05) to patterns of growth and kernel yield of the crop. The 3 t ha-1 rice-husk ash is recommended. No significant yield advantage was observed at 4 t ha-1.