Soil chemical properties and maize yield after application of organic and inorganic amendments to an acidic soil in southwestern Nigeria

Abstract

A factorial experiment with a randomised complete block design (three replicates) was performed to determine the effects of poultry manure (PM), lime (L) and NPK 15-15-15 fertilizer on soil chemical properties, and to determine the effects of their combinations on soil productivity and maize yield. The factors were PM (0, 5 and 10 Mg ha-1), L as CaCO3 (0 and 250 kg ha-1) and NPK 15-15-15 (0 and 100 kg ha-1). The soil had a loamy sand texture. The application of L and PM increased the surface soil pH in a similar fashion. In both years of the experiment, the effective cation exchange capacity (ECEC) of the soil after the combined application of 10 Mg ha-1 PM, L and NPK was significantly higher than after the individual application of L or NPK or their combination (5.75-7.65 cmol kg -1 compared to 3.36-4.57 cmol kg-1). The application of 10 Mg ha-1 PM with L and/or NPK reduced the possibility of Mn toxicity, with soil levels ranging from 108 to 136 mg kg-1. The combined use of the three amendments gave the highest leaf nutrient concentrations. The highest maize grain yield (4.62 Mg ha-1) was obtained with L + 10 Mg ha-1 PM; with no amendment the grain yield was 1.9 Mg ha -1. The application of PM enhanced the effects of L and NPK in improving soil productivity. However, separate applications of 5 and 10 Mg ha-1 PM similarly affected soil productivity; the sandy nature of the soil at depths of 0-20 cm seems to have prevented differences between the two rates from becoming manifested.