Abstract
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.
Highlights
RESUMO - Contrariamente aos fertilizantes nitrogenados de eficiência aumentada, principalmente a ureia, os fertilizantes fosfatados foram pouco estudados e as informações disponíveis são limitadas
The growth and production characteristics of the lettuce were significantly influenced by the dosage and form of monoammonium phosphate (MAP), and by the interaction between these factors (Table 2); except for dry weight and number of leaves per plant, plant circumference and plant length
The fresh weight of the lettuce shoots increased with the increase in P2O5 dosage, and were higher at dosages up to 651 mg kg-1 P O with the application of MAP + polymers
Summary
RESUMO - Contrariamente aos fertilizantes nitrogenados de eficiência aumentada, principalmente a ureia, os fertilizantes fosfatados foram pouco estudados e as informações disponíveis são limitadas. Dessa forma, objetivou-se com o presente trabalho avaliar as características produtivas, nutricionais e a eficiência agronômica da adubação fosfatada com MAP revestido com polímeros em dois cultivos subsequentes de alface. Os resultados mostraram que o MAP revestido com polímeros promoveu maior eficiência da adubação fosfatada nos dois cultivos da alface, melhorando o aproveitamento do fósforo residual. As características produtivas e nutricionais da alface foram influenciadas pelas doses de P2O5 e com a utilização do MAP + polímeros. The global fertilizer industry faces an ongoing challenge to improve the efficiency of its products. This is done by generating technologies which can be incorporated into existing fertilizers in order to increase nutrient usage (TRENKEL, 2010)
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