SPATIAL DISTRIBUTION OF AVAILABLE FE ON LITHOSEQUENCE GROWN TO TARO IN SOUTHEASTERN NIGERIAN

Fe is an essential micronutrient required for optimum growth, yield and quality of taro (Colocasia esculenta (L) Schott, a major carbohydrate staple food in Nigeria and the tropical regions. Spatial distribution of Fe on a lithosequence of late Tertiary era (> 5,000 years ago) in southeastern Nigerian where taro is a major crop in the farming system was estimated using kriging technique. The parent materials are coastal plain sands, shale and sandstone respectively, estimated to cover about 4.28 million hectares (m ha). 69 soil samples were collected at geo-referenced locations at 0 – 30 cm depth and analyzed. Data generated from soil analyses were further subjected to geostatistics to quantitatively estimate spatial distribution of available Fe. Results showed that about 1.90 million ha (44.4%) mostly covered by sandstone is low in available Fe (< 20 mg/kg). However, over half of the study area (53.5%) representing 2.29 m ha, predominated by coastal plain sands and shale is moderate in available Fe (20 – 30 mg/kg). Application of Fe micronutrient as a foliar application or incorporating it into NPK fertilizers and integrated (organo-mineral) plant nutrient management is recommended to increase yield and quality of cocoyam corms and cormels and sustain soil health in the area.