Nutrient uptake and removal by potato cultivars as affected by phosphate fertilization of soils with different levels ofphosphorus availability

Studies in the past decades have focused on how tuber yield of potato grown on different types of soil is affected by phosphate fertilizer rates. However, little is known about the effects of phosphorus availability in the soil and of phosphate fertilization on nutrient uptake and removal by the main potato cultivars currently grown in Brazil. Thus, in this study we investigated the influence of P fertilization rates on dry matter (DM) yield and nutrient uptake and removal in five potato cultivars grown on soils with different levels of P availability. Experiments were conducted on soil with low (14 mg dm^-3), medium (36 mg dm^‑3), and high (70 mg dm^-3) P availability, in randomized complete blocks with a 5 × 5 factorial arrangement with four replications. The treatments consisted of five potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial) and five P rates (0, 125, 250, 500, and 1,000 kg ha^-1 P₂O₅) applied in the planting furrow. In soils with low, medium, and high P availability, P fertilization increased plant growth and tuber DM yield up to rates of 500, 250, and 125 kg ha^-1 P₂O₅, respectively. At a specific initial P availability, all potato cultivars responded to the same P rate for plant growth, tuber yield, and nutrient uptake and removal. At the highest P fertilization rates, leaf analysis showed that the nutritional status of potato plants was not significantly changed and no nutritional deficiency was induced, regardless of the soil P availability levels. However, in the soils with higher P availability, P fertilization decreased plant Mn and Zn and tuber Mn concentrations in a linear manner. The increases in the uptake of N, K, Ca, Mg, S, B, Cu, and Fe and the removal of most nutrients in response to P fertilization were related more to the increase in plant biomass and tuber DM yield than to changes in concentrations of these nutrients in the plant. Application of P at high rates in soil with high P availability caused luxury P uptake, which reduced Mn uptake by 10 % and prevented higher Zn uptake, by reducing plant Zn concentrations, despite the increase in plant biomass.