Doses and sources of phosphorus in maize with and without polymer coating in thhe mono-ammnnium phosphate

The Brazilian soils have low levels of phosphorus available, due to high acidity, therefore, is fundamental the application of phosphate fertilizers for high yields. The objective was to evaluate the efficiency of phosphate fertilizers with mono-ammonium phosphate (MAP) associated with two doses and two sources of phosphorus in corn. Experiment was carried out under no-tillage system in Nov/2010, in Ijaci - MG. The experimental design was randomized block, 2x2 factorial + 1 (2 P rates: 70 and 140 kg P2O5 ha-1, 2 P sources: MAP and MAP-coated with Policote® and the witness without P2O5). It was used the hybrid GNZ 2004. The evaluations consisted in the measuring of the plant height at 30 days after emergence (PH), leaf phosphorus content (P%), grain yield (GY) and the agronomic efficiency of the applied phosphorus (EIPA). The highest dose of P2O5 provided increments in the AP and P% PG. The different sources of phosphorus affect the characteristics studied in a similar manner and were independent of the source of MAP. The substitution of phosphorus from the MAP by the MAP Coated with Policote® or even in the absence of fertilizer did not affect the efficiency of the fertilizer evaluated by traits.