Granular and Powdered Lime Improves Soil Properties and Maize (Zea mays L.) Performance in Humic Nitisols of Central Highlands in Kenya

Soil acidity is a major constraint to crop production on highly weathered tropical soils characterized by high Aluminum (Al) toxicity, low cation exchange capacity, and low phosphorus (P) availability to plants. The objective of this study was to evaluate the effects of two powdered limes (calcium oxide, calcium carbonate), granulated lime (CaO.MgO), and their combinations with mineral fertilizer on soil chemical properties (soil pH, organic carbon, exchangeable acidity, total N, available P and exchangeable bases (Mg2+, Ca2+), and maize stover and grain yields. Field experiments were established in two sites. The experiment was implemented in a randomized complete block design, replicated four times. They were carried out for two consecutive seasons. Data were subjected to analysis of variance (ANOVA) and mean separated using Duncan's Multiple Range Test. Results showed that liming led to significant increases in soil pH and a reduction in exchangeable acidity. Use of CaCO3 recorded the highest pH increase in the extremely (+19%) and moderately (+14%) acidic sites. The application of all lime types and sole fertilizer increased soil available P in both seasons and sites. Maize grain yields were lower in treatments receiving sole fertilizer and sole lime compared to lime and fertilizer combinations. CaCO3 + fertilizer recorded the highest grain yield in both the extremely (5.34 t ha-1) and moderately (3.71 t ha-1) acidic sites. In the extremely acidic site, lime should be applied together with fertilizers. CaCO3 was the best in ameliorating acidic soil in terms of reducing soil acidity and increasing P availability, and improving maize grain yields.