Potassium, calcium and magnesium in carrot crop fertilization

Resumo

The balanced relationship between potassium (K), calcium (Ca) and magnesium (Mg) reflects on carrot’s quality and yield. We evaluated the use of potassium sources associated with calcium and magnesium doses in carrot cultivation. A randomized block design in a triple factorial scheme (2x2x2) was performed with the following factors: First - Potassium chloride (KCl) (120 kg K₂O ha^-1); Potassium sulfate (K₂SO₄) (120 kg K₂O ha^-1); Second - Doses of Mg sulphate (MgSO₄): Zero or 25 kg Mg ha^-1; Third - Doses of L. calcareum seaweed (product of Ca): Zero seaweed or 200 kg seaweed ha^-1, with six blocks. For base fertilization, 40 and 600 kg N and P₂O₅ ha^-1 were supplied via MAP and triple superphosphate, respectively, in all treatments. Total and commercial yield, 3A yield and carrot discard percentages were evaluated. Regardless of the K source used, the yield was higher when no Ca or Mg dose was applied. The application of 25 kg Mg ha^-1 without Ca altered the Ca:Mg ratio in the soil and resulted in a significant yield increase when KCl was used. The association of L. calcareum algae with KCl reduces total yield and increases carrot disposal. The use of L. calcareum algae as a Ca source only provided a significant increase in yield when associated with the application of 25 kg Mg ha^-1 via MgSO₄ and when the K source was K₂SO₄.