Characterization and Classification of Rice - Growing Soils on Igbaku Sandstones Residua and Current Suitability for Rice Production in Anambra State, Eastern Nigeria

The soils on Igbaku sandstones residua were sample at Ifite Ogwari in Anambra state Nigeria to characterize, classify and evaluate their current suitability for rice production. Following several auger borings, a modal profile was sited dug, de- scribed and sampled. Data from it and representative auger points are presented. The soils generally belong to loamy textural classes or finer, especially in the subsoil layers. The implications of particle size distribution and textural classes obtained suggest high water retentivity favoured by slow permeability, both of which support good rice performance. Again the values of bulk density, pore size distribution and hydraulic conductivity are all in the ranges that favour rice culti- vation. Though the soils contained high levels of exchangeable bases, exchangea- ble acidity was equally high, leading to low base saturation. The soils were clas- sified as Haplaquaults (Soil Taxonomy) and correlated to Gleyic Cambisols (WRBSR). Due to fertility inadequacies, the current suitability of the soils for rice production is the S2f subclass. This implies that for sustainable rice produc- tion (especially if three cycles per year is to be achieved) supplementary nutrient especially P2O5 from triple superphosphate need to be applied and acid-forming fertilizers should be avoided rather than superphosphates should be used. Based on the soil chemical results, the following recommendations were made: 100-120 kg ha-1 Urea, 60 kg P2O5 kg ha-1 from triple superphosphate and 15 kg ha-1 K2O ( muriate of potash)