Characterization and classification of rice-growing soils on Imo clay shale residua in Eastern Nigeria and current suitability for rice production: II. Anaku and Igbariam communities.

The soils on Imo Clay Shale residua were sampled at Anaku and Igbariam in Anambra state, Nigeria to characterize, classify and evaluate their current suitability for rice production following standard scientific procedures. After several auger borings, modal profiles were sited, dug, described, and sampled. The soils generally belong to loamy textural classes or finer, especially in the subsoil layers. The morphological and physical properties of soils showed that the soils were poorly drained, favouring high water retention due to low hydraulic conductivity and slow permeability. All these conditions favour good rice performance. Though the soils contained high levels of exchangeable bases, exchangeable acidity was equally high leading to low base saturation (< 35%). Thus, the soils were classified as Typic Kanhaplaquults (Soil Taxonomy) and correlated to Gleyic Cambisols (World Reference Base for Soil Resources). Due to fertility inadequacies, the current suit- ability unit of the soils for rice production is suitability class 2 with fertility constraints (S2f). This implies that for sustainable rice production supplementary nutrients especially P2O5 from triple superphosphate or rock phosphate need to be applied. Based on the soil chemical results the following recommendations were made for optimum rice production: 100.00-120.00 kg ha‒1 urea, 60.00 kg ha‒1 P2O5 from triple superphosphate and 15.00 kg ha‒1 K2O (muriate of potash).