Limestone application effects on common bean (Phaseolus vulgaris L.) yield and grain iron and zinc concentration on a Ferralsol soil in Uganda

Soil acidification has major ramifications on crop production because low pH soils are less productive. The objective of this study was to determine the effect of limestone application on yield and grain iron (Fe) and zinc (Zn) concentration in newly released high iron and zinc, drought resilient varieties of common bean (NAROBEAN 1 and 3). Using a split-plot in time design, an experiment was set up using three common bean varieties (NABE 15, NAROBEAN 1 and NAROBEAN 3) as split plots and seven rates of limestone as main plots. The experiment was done for two rainy seasons on a Ferralsol soil in central Uganda. The results showed that soil pH, cation exchange capacity (CEC) and soil concentration of Ca and Na increased with greater amounts of limestone applied to the soil. On average, NAROBEAN 1 had 30 and 48% greater yield than NABE 15 and NAROBEAN 3 in both seasons, respectively. Grain Fe and Zn concentrations were not affected by limestone application. However, across seasons, NAROBEAN 3 seeds contained 12 and 15% more zinc and, 10 and 20% more iron than NAROBEAN 1 and NABE 15, respectively. Overall, limestone application did not impact yield or yield components of common bean.  Key words: Micronutrients, acidic soils, liming, biofortification, soil reaction.