Tuber yield and economic result of ‘Atlantic’ potato in response to NPK fertilizer formulas

Resumo

The usual application of high rates of 4-14-8 NPK fertilizer 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 formula does not always meet 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 furrow. The rates of both fertilizer formulas were calculated to reach P₂O₅ rates of 210, 420, and 630 kg ha^-1. At each P₂O₅rate, 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 NPK 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 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 formula 6-30-6 studied in this work) provides lower costs, and greater operational efficiency and profits in relation to the 4-14-8 formula traditionally used in the potato crop.