Sweet potato yield and physical and chemical properties of soil in function of organic and mineral fertilizers

Sweet potato crop is usually cultivated with low fertilization investments, but the crop can present significant yield increase when correct fertilization is carried out in its cultivation. In this study aimed to evaluate the influence of the use of different fertilizer sources and doses on sweet potato yield and on physical and chemical properties of soil. The experimental design was a randomized block in 3x5 factorial scheme, with three replications. The treatments were composed of fertilizer sources (chicken manure, mineral fertilizer with chemical composition equivalent to the nutrients found in chicken manure and blend of chicken manure (50%) with mineral fertilizer (50%) equivalent to the sum of nutrients found in chicken manure) and fertilizer doses (nutrients equivalent to 0, 3, 6, 9 and 12 t ha(-1) of chicken manure). As result of study, it was found that the crop responds to soil fertilization with increases in total and commercial yields with the use of chicken manure, mineral fertilizers and the combination of both until the doses of 5.8, 6.5 and 7.0 t ha(-1), respectively. Fertilization with chicken manure, alone or in combination with chemical fertilizers, promotes highest yields. There is no difference in soil bulk density and in total soil porosity as a function of fertilizer sources or doses. The addition of fertilizer promotes increases in pH and P, K, Ca and Mg levels in the soil in relation to soil without fertilizer.