Effect of different rates of liming on soil ph, p and agronomic traits of common beans in eastern Uganda

Abstract

Low soil pH and low soil available phosphorus, are major soil fertility problems with the soils under common bean production in East Africa. The major objective of this study was to develop a soil acidity management strategy for common beans production in Eastern Uganda by determining the effect of different rate of liming on soil pH, soil available P and agronomic traits of common beans. This was achieved through a laboratory-based incubation and a greenhouse experiment. The greenhouse trial used RCBD with four replications and ran for 70days while the incubation experiment used CRD with three replicates for 30 days. This was done out on acidic silty clay loam soils from Wera sub county Amuria district in E. Uganda. The data collected were subjected to analysis of variance (ANOVA), available P was analyzed using Bray 1 method. All the collected soil samples were acidic in reaction and pH varied from 4.89 to 6.69 with mean value of 5.612, available P was 3.2mg/kg with the textural class of silty clay loam (clay 35%, silt, 55% and sand 10%). Addition of CaCO3 at different rates (0tons, 3tons, 4tons, 5tons, 6tons and 7tons/ha) to the soils significantly increased both pH and soil available P in the soil. Notably application of lime had significant effect on soil pH with the (p<.001) where 7tons/ha had the highest pH value of 6.69 and control had least value of 4.98. But liming at 6tons/ha met the liming requirement of the soils with 6.06 pH values. On the other hand, CaCO3 also had a significant effect on the soil available P with (p<.001) where 7tons had the highest value 18.8mg/kg and control had the least with 4.1mg/kg of soil but 5 and 6tons raised the available soil P to 11mg/kg - 14.8mg/kg a range suitable for common beans (10-15mg/kg). Finally, there was a significant effect of all the treatments on the agronomic traits & 100 grain weight of beans with (plant height, leave number, tap root height, pod number and grain weight) having (p<.001) while branch number was not significantly affected (p>.001). Agronomically, application at 6tons/ha had the best performance compared to all the other application rates and it also showed the highest economic efficiency of 335.18% compared to other liming rates.