Response of soybean (Glycine max L.) to application of lime and phosphate fertilizer in an acid soil of western Kenya

Abstract

The effect of combining lime and phosphate fertilizer on the performance of soybean (Glycine max L.) was investigated in a pot experiment consisting of nine treatments of three rates of lime (0, 4 and 8 t ha−1) in a factorial combination with three rates of phosphorus (0, 15, and 30 kg P ha−1) at Maseno University in western Kenya. There was a significant interaction between the lime and phosphorus rate on the biomass dry weight of soybean. At the rates of 0 and 4 t ha-1 of lime, the biomass dry weight of soybean increased with increasing rates of phosphorus but at 8 t ha-1 of lime, the dry weight of soybean increased from 0 to 15 kg P ha-1 but declined at 30 kg P ha-1. There was however no significant interaction between lime and P rates on grain weight but the effects of both P and lime rate were significant. When applied without lime, 30 kg P ha-1 gave significantly higher grain (5.3 g pot-1) weight than 15 kg P ha-1 (1.6 g pot-1) of soybean, which was also significantly better than the control (0.0 g pot-1). When applied without phosphorus, both lime rates at 4 and 8 t ha−1 significantly increased grain weights of soybean compared to the control, but the grain weights of soybean between the two lime rates did not differ significantly. The highest yields of soybean were obtained when 4 t ha−1 of lime was applied with 30 kg P ha−1 (19 g pot-1). Therefore, this study demonstrates that the ameliorating deleterious effects of soil acidity through liming should simultaneous be accompanied by application of P fertilizer at appropriate rates.