Nutrients concentrations in the flag leaf and grains of black-oat affected by phosphate and potassium fertilization

The black oat (Avena strigosa Schreber) has been commonly used as green manure, in crop rotation systems under no-tillage, fall-winter crop, and for cattle grazing, hay, and silage. The objective of this work was to evaluate the nutrient concentrations in the flag leaf and grains of black-oat affect by phosphate and potassium fertilization. The experiment was carried out under field conditions on a Rhodic Nitosol, in Botucatu, São Paulo State, Brazil. Three doses of single superphosphate (0, 40 and 80 kg.ha-1 of P2O5) and three of potassium chloride (0, 20 and 40 kg ha-1 of K2O) were tested as a factorial (3 x 3), in a randomized complete block design, with four replicates. The fertilizers were applied in the sowing row. Ammonium sulphate was supplied for all plots (20 kg ha-1 of N applied at sowing and 30 kg.ha-1 after tillering stage). The concentrations of Ca, Mg, S, Fe, Mn, Cu and Zn in the flag leaf and the P and K concentrations in the grain were increased by phosphate fertilizer application. The potassic fertilization had no effect on the concentrations of nutrients in the flag leaf and grains of black-oat.