Nitrogen and potassium in the cultivation of Piatã grass in Brazilian Cerrado soil

Nitrogênio e potássio no cultivo do capim-piatã em solo do Cerrado brasileiro

ABSTRACT

This study aimed to evaluate the production and mineral nutrition of Piatã grass as a function of nitrogen and potassium fertilization in Oxisol collected in the Cerrado. The experiment was carried out in a greenhouse, the experimental design was completely randomized, in a 5 x 5 factorial scheme, corresponding to five nitrogen doses (0, 100, 200, 300 and 400 mg dm^-3 of N) and five potassium doses (0, 90, 180, 270 and 360 mg dm^-3 of K₂O), with four replicates. Three cuts of the shoots were performed every 30 days. Chlorophyll index, dry mass of shoots and roots, and nitrogen and potassium contents in the leaves were evaluated. The dry mass of shoots showed interaction between nitrogen and potassium in the three cuts; in the second and third cuts, it had maximum production at the nitrogen and potassium doses of 254 and 158 mg dm^-3, in the second, and 250 and 306 mg dm^-3 in the third, respectively. The nitrogen and potassium contents are influenced as a function of nitrogen and potassium fertilization isolated by factor. The nitrogen and potassium ratio in the Piatã grass crop was around 1:1.

Key words:
Brachiaria brizantha; nitrogen content; potassium content; N:K ratio in plants