Correction of nutrition disorders of sweet potato and taro: Fertilizers and soil amendments

Little information is available on appropriate fertilizer application for many crops of lesser importance on a world scale, in spite of their value in local communities. Also, the extent and severity of nutrition disorders is not known with any confidence. Until more information is available, the nutrition requirements of tropical root crops, including sweet potato (Ipomoea batatas (L.) Lam.) and taro (Colocasia esculenta (L.) Schott), can be estimated on the basis of nutrient removal by harvested tubers and corms. Additional information may be gained from the response of other crops to fertilizers. Nutrient removal in excess of soil reserves will inevitably result in land degradation through nutrient decline in either subsistence or commercial agriculture. Fertilizer rates, especially of nitrogen (N), phosphorus (P) and potassium (K), are available primarily for the latter system. Before more accurate recommendations can be made for sweet potato and taro, however, accurate diagnosis and knowledge of the extent and severity of nutrition disorders are required.