Effect of Lime Application on Soil Acidity and Maize Yield in Enugu State

This study examines the effect of agricultural lime application on soil pH correction and maize grain yield in acid soils of Enugu State, South East Nigeria. Soil acidity is one of the most widespread soil fertility constraints in Southeast Nigeria's humid forest zone, limiting crop productivity through aluminium and manganese toxicity, phosphorus fixation, and impaired microbial activity. Liming is the standard agronomic treatment for soil acidification, but the appropriate lime rate for Enugu State soil types and the interaction with fertiliser response have not been adequately quantified. This study establishes a randomised complete block design experiment at the University of Nigeria Nsukka research farm, applying agricultural limestone at four rates: 0, 1, 2, and 3 tonnes per hectare, in combination with two NPK fertiliser levels (0 and full recommendation). Soil pH, aluminium saturation, available phosphorus, maize plant height, and grain yield are measured. Findings reveal that 2 tonnes per hectare of lime raises soil pH from 4.6 to 6.1, eliminates aluminium toxicity, and increases available phosphorus by 68 percent. Maize grain yield under liming combined with full NPK reaches 5.6 tonnes per hectare compared to 1.8 tonnes per hectare in the acid, unfertilised control. The lime-by-fertiliser interaction is highly significant, demonstrating that fertiliser response is substantially enhanced by prior liming. The study concludes that 2 tonnes per hectare of lime combined with recommended NPK is the most cost-effective treatment for maize production on acid soils in Enugu State.

Keywords: lime application, soil acidity, maize yield, Enugu State, aluminium toxicity.