Fertilizantes fosfatados e nitrogenados com proteção integrada para a produção de milho

Abstract

Currently, increasing the use of fertilizers generates increases in production and costs reduction in agriculture. The objective of this study was to evaluate the influence of the use of phosphate and nitrogen fertilizers of integrated protection in the corn crop. Three chapters will be presented, being the first a literature review of the topics covered by this study and the other two related to the results of the field experiments. The field experiments were carried out using a randomized block design, with four replications (experiment in chapter three, three repetitions were used), in a 3x5x2 factorial arrangement; the study factors consisted of three sources of phosphate fertilizers apllications. (Conventional monoammonium phosphate - MAPCONV, (11-46-00); Polymerized monoammonium phosphate - MAPPOL, (09-44-00); Organic cake pie monoammonium phosphate - MAPTF, (06-30-00) in five dosages P2O5 (0, 50, 100, 150 and 200 kg ha-1), combined with two sources of nitrogen fertilizers (conventional urea - UC, 45% N and urea with urease inhibitor additive - NBPT, 42% N). In chapter two, yield, morphological aspects and available P in the soil were evaluated. In chapter three, we evaluated the nutritional aspects (P and N) of the plant and the production of dry mass throughout, the cultivation period. The data were submitted to analysis of variance, and the effects within the qualitative factors were broken down into orthogonal contrasts and for the quantitative factor, regression models were adjusted. The use of phosphate fertilizers with technologies did not provide higher yield than the use of conventional fertilizer, except for the dose of 50 kg ha-1 of P2O5. The NBPT did not provide differences in maize yield, compared to the treatments with urea. From the P2O5 dose of 100 kg ha-1, treatments with MAPTF showed less phosphorus availability at the end of the cultivation period. Our results showed that the higher the phosphorus doses the higher the leaf P content and plants dry mass. The sources of P with technology were superior to the conventional source to increase the nitrogen content and the dry mass of the plants. The higher P content in the leaf tissues were found in the phosphate fertilizer coated with polymers treatments.