Yield of sweet potato as a function of organic fertilization and intercropping with Crotalaria juncea

Abstract

In the northern region of Brazil, information for the sweet potato regarding suitable soil management, especially organic fertilisation and intercropping with species of green manure, are still in the early stages. The aim of this research therefore, was to evaluate the effect of poultry litter on the yield of sweet potato roots grown under a monocrop system and when intercropped with sunn hemp (Crotalaria juncea) under the soil and climate conditions of the State of Roraima. The experiment was carried out in the field from August to December of 2014, in the Sector for Olericulture of the School of Agricultural Technology, on the Murupu Campus of UFRR in the town of Boa Vista, Roraima. A randomised block experimental design was used, with three replications, in a (5 × 2) + 1 factorial scheme, representing five doses of poultry litter (0, 5, 10, 15 and 20 t ha-1), with sweet potato as both a monocrop and intercropped with sunn hemp, and one additional treatment with organic and mineral fertiliser. Slips of the Granfina variety of sweet potato were used for planting. Seeds of sunn hemp were sown in double rows between the rows of sweet potato 30 days after planting the slips, with the first cutting carried out 90 days after sowing. The addition of poultry litter to the soil increased the total production of sweet potato roots for the crop planted in Roraima, whether intercropped or not with sunn hemp. Despite the benefits to sweet-potato yield from the addition of poultry litter and the intercrop with sunn hemp, total productivity was greater in the additional treatment that received organic and mineral fertiliser.