Tuber yield and economic result of ‘Atlantic’ potato in response to NPK fertilizer formulas
ABSTRACT The usual application of high 4-14-8 NPK fertilizer rates in the potato planting furrows, independently of the soil fertility or nutritional cultivar requirements, has become a paradigm in Brazil. However, the 4-14-8 NPK formula does not always meet the crop needs, and can unbalance the availability of nutrients in the soil. The objective of this study was to evaluate the tuber yield and economic results of ‘Atlantic’ potato as affected by rates of 4-14-8 and 6-30-6 NPK formulas applied in the planting furrows. The rates of both NPK formulas were calculated to reach P2O5 rates of 210, 420, and 630 kg ha-1. At each P2O5 rate, the 6-30-6 formula resulted in less 30% N and 65% K2O in the planting furrow compared to 4-14-8 formula. A randomized complete block design in a factorial scheme (2×3)+1, including an unfertilized furrow control, with three replications was used. Only the use of 6-30-6 formula increased the total tuber yield of ‘Atlantic’ potato. The marketable tuber yield reached higher levels (29.8 t ha-1) with higher P2O5 rate (440 kg ha-1) using the 6-30-6 than 4-14-8 formula. The fertilizer rates and formulas NPK did not affect specific gravity of marketable tubers. Therefore, the use of a fertilizer more concentrated in P2O5 that favors smaller contributions of N and K (as the 6-30-6 formula studied in this work) provides lower costs, and greater operational efficiency and profits in relation to the 4-14-8 formula traditionally used for the potato crop.