Removal of nutrients by potato tubers was evaluated in response to the application of potassium sulphate to potato crops. Potassium was applied at six different rates (0; 60; 120; 240; 480 and 960 kg ha-1 of K2O), as K2SO4 and placed during planting time in the furrow. Two plants/plot were sampled 20 days after plant emergence (DAE), 48 DAE and at harvest to evaluate N, P, K, Ca, Mg, S, Cl, Mn and Zn contents and removal by the tubers. A factorial (6x3), with six K2O rates and three sampling times was set up in a randomized block design with four replications. The application of K2SO4 increased Cl, Mn and Zn concentration in potato tuber. Increasing K2SO4 fertilization affected potato tuber removal of nutrients only at harvest, when the application of potassium fertilizer increased the removal of K, Ca, Mg, S, Mn and Cl. At maximum tuber yield, nutrient removal were: 99.1 kg ha-1 N; 14.2 kg ha-1 P; 118.5 kg ha-1 K; 2.10 kg ha-1 Ca; 6.50 kg ha-1 Mg; 9.28 kg ha-1 S; 8.18 kg ha-1 Cl; 47.8 g ha-1 Mn and 102.5 g ha-1 Zn. Nutrient removal by tubers represents an important source of nutrient loss from the soil, and its evaluation should be used to calibrate fertilizer recommendations.
Solanum tuberosum L.; potassium application; macronutrient; micronutrient
