Productivity and efficiency index of potassic fertilization in cabbage

Abstract

Cabbage presents high growth rate, which demands studies with potassium fertilization due to the high extraction and export of potassium (K). The objective of this study was to evaluate the productivity and efficiency index of K in the plant and soil in response to doses and sources of this nutrient applied to cabbage crop. Two field experiments were conducted in areas with different soil K availability. The experiment was designed as randomized blocks with four replicates. The treatments consisted of five doses of K2O (0, 100, 200, 400 and 800 kg ha-1) applied with Potassium Chloride (KCl) source, and an additional treatment with Potassium Sulphate (K2SO4) source at the dose of 200 kg ha-1 of K2O. Cabbage shows high use efficiency and recovery efficiency of K from soil under low K availability conditions. High yields may be achieved by applying low K doses. The crop accumulated high quantities of K in the shoot, but without having increases on productivity with rising K doses. Potassium export was most of the accumulated in the shoot in both growing seasons, which shows that cabbage is a high demanding crop. The differences between K2SO4 and KCl sources were minimal on productivity and efficiency index of potassium fertilization in cabbage.