Sweet potato crop response to phosphate fertilization

Abstract

ABSTRACT Sweet potato yields in Brazil are well below the crop’s potential due to inadequate soil fertility and fertilization management. This study aimed to evaluate the effect of phosphate fertilizer on sweet potato yield and nutrition under field conditions. Five rates of P2O5 (0, 100, 200, 400 and 600 kg ha−1) were evaluated in areas of Humic Cambisol, in two cropping seasons. The maximum technical efficiency (38.5 t ha−1) occurred with a rate of 380 kg ha−1 of P2O5, and the economic optimum rate with 121 kg ha−1 of P2O5, corresponding to the marketable yield of 33.3 t ha−1. The sweet potato’s response to the phosphate fertilizer application in Humic Cambisol decreases or ceases if the available P level is higher than 13 mg dm−3, corresponding to the marketable yield of 37.7 t ha−1. The increase in the P2O5 rates in the soil resulted in a negative correlation between P and Fe, P and B, P and Cu, and P and Zn in the shoot, and a negative correlation between P and K in the shoot, storage root and whole plant.