Digital land suitability assessment in Southwest Nigeria for maize production using most-limiting soil native fertility factors and geographical information system

Abstract

Maize production per hectare in Southwest Nigeria ranks among the lowest compared to other regions worldwide. Digital methodologies focusing on soil fertility determinants and geographic data were used to evaluate land suitability. We explored a methodology that combined ordinal logistic regression with continuous soil characteristic modeling in a two-step mapping approach to assess land suitability. A stepwise forward regression analysis was performed on environmental variables to identify those that significantly influenced the outcomes at a 95 % confidence level (p < 0.05). Most areas in the region, from the north to the south, had organic carbon concentrations below 1 %. In the northern part, a significant portion showed total nitrogen levels below 0.1 g kg⁻¹. The majority of the area had exchangeable phosphorus levels ranging from 23 to 28 mg kg⁻¹, while some eastern locations had extractable potassium levels above 0.40 g kg⁻¹. Only a few sites in the southern region showed pH values of 5.50 or lower; others exceeded that level. According to the FAO land suitability classification, 29.87 % was rated as unsuitable, 69.08 % as moderately suitable, and just 1.06 % as suitable for maize cultivation. We recommend developing and enforcing policies to oversee infrastructure development and protect agricultural land. It is crucial to discourage non-regenerative farming practices, and both the government and private sectors should support farmers by providing access to modern soil resources.