Evaluation of the Agronomic Characters of Sweet Potato Varieties Grown at Varying Levels of Organic and Inorganic Fertilizer

Sweet potato (Solanum tuberosum), a staple tuber crop in parts of the Sudan and Guinea savanna zone of Nigeria is known for its resistance to drought, vigorous early growth and low input requirements. Increase in population which has resulted to land shortages has led to reduction in traditional methods of maintaining soil fertility. Technologies based on combinations of organic and inorganic sources of fertilizer would produce higher and more sustainable yields than either organic or inorganic fertilizer alone or farmers’ indigenous management practices. Field trials to evaluate the agronomic characters of two sweet potato varieties were conducted during the wet seasons of 2004 and 2005 at the Institute for Agricultural Research (IAR) farm Samaru Zaria. The treatments consisted of three rates each of organic and inorganic fertilizer and two varieties of sweet potato. Organic and inorganic fertilizer application did not have significant effects on vine length, number of leaves, number of branches and total dry matter. Dan Zaria however produced significantly more number of branches than Dan Bakalori, which is attributed to differences in genetic composition of the sweet potato varieties. Application of organic fertilizer increased the yield of sweet potato in both years. Yield obtained from the variety Dan Bakalori was significantly heavier than that obtained from Dan Zaria. Application of 4t/ha organic fertilizer resulted in the highest yield of sweet potato which was not significant. The result however suggests that further increase in organic fertilizer might lead to increases in yield. This requires further long term studies.