The influence of organic fertilization on total and commercial production of sweet potato roots, Rainha Branca cv. was evaluated. The experiment was carried out from June to October/2004, in Paraiba State, Brazil. The experimental design was of randomized blocks with six treatments (0; 10; 20; 30; 40 and 50 t ha-1 of cattle manure), in four replications. The total and commercial productions of sweet potato roots were 18.5 and 14.2 t ha-1 obtained with 32 and 30 t ha-1 of cattle manure. The cattle manure level responsible for maximum economic return of commercial roots (30 t ha-1), was equal to that which allowed maximum production, represented 100% of maximum technique efficiency, constituting an indicative of the economic viability of cattle manure application in sweet potato. The estimated cattle manure levels which resulted maximum production and economic returns for commercial roots, corresponded to 13.8 g kg-1 of remaining organic matter with the extractor. In similar soils of this study, the organic fertilization for sweet potato production can be dispensed, with remaining organic matter level higher than 13.8 g kg-1 of soil.
Ipomoea batatas; organic fertilization; root production
