Productive characteristics, nutrition and agronomic efficiency of polymer-coated MAP in lettuce crops

Resumo

In contrast to enhanced-efficiency nitrogen fertilisers, principally urea, phosphate fertilisers have been little studied and the available information is limited. The aim of this work therefore was to evaluate the productive and nutritional characteristics and the agronomic efficiency of a polymer-coated MAP fertilizer on two subsequent lettuce crops. The experiment was carried out in a greenhouse, in pots with a capacity of 4 kg, filled with a dystrophic yellow Latosol of a clayey texture. The experimental design was completely randomised and the treatments arranged in a 2 x 5 factorial scheme: two sources of phosphorus (P) (MAP and polymer-coated MAP), applied to the plots in five dosages (0, 100, 200, 400, 800 mg P2O5 kg-1) with three replications. The results showed that the polymer-coated MAP increased the efficiency of the phosphate fertilizer in both lettuce crops, improving utilisation of the residual phosphorus. The agronomic efficiency of fertilization decreases with the increases in applied phosphorus. The production and nutritional characteristics of the lettuce were influenced by the levels of P2O5 and the use of MAP with polymers. Higher values for dry and fresh weight and for the accumulation of P in the first crop occurred with the use of polymer-coated MAP at dosages of 506.9, 450.1 and 522.8 mg kg-1 P2O5.