Polímeros orgânicos com ureia dissolvida e doses de nitrogênio no milho

The efficiency of nitrogen fertilization with urea can and should be improved, therefore, research with alternative forms of urea due to the gradual availability of nitrogen are very important. Thus, the objective of this study was to evaluate the effect of N doses in latex-based organic polymers form with dissolved urea, evaluating nutritional status, production components and grain yield of corn, as well to analyze the residual N in organic polymers and the agronomic efficiency of the treatments. The experiment was conducted in Selvíria - MS, in a Latossolo Vermelho distrófico (red oxisol) under no-tillage system. The experimental design was a randomized block design with four replicates arranged in a 5 x 4 factorial scheme: 5 N sources (P1 = organic polymer with 30% urea dissolved in water and 6.86% N, P2 = Organic polymer with 70% urea dissolved in water and 19.35% N, P3 = organic polymer with 30% dissolved urea and 9.65% N, P4 = organic polymer with 70% dissolved urea and 11.00 % Of N and U = urea with 45% of N) and 4 N doses (0, 60, 120 and 180 kg ha-1). The N sources provided maize yield similar. However, at higher N rates (120 to 180 kg ha-1), the polymer P1 had the highest agronomic efficiency, although P2 have excelled in 120 kg ha-1 of N. The grain yield of maize increased linearly with increment of N rates of polymers P1, P3 and P4 and up to a dose of 107 kg ha-1 N for the P2 polymer.The efficiency of nitrogen fertilization with urea can be improved mainly due to the volatilization losses of ammonia. In this context, the use of organic slow-release polymers can be an efficient alternative for a better use of the applied nitrogen fertilizer. The objective of this study was to evaluate the effect of N doses as latex based organic polymers with dissolved urea sources, evaluating the nutritional state, productive components and corn grain yield, as well as to analyze the residual N in the organic polymers and the agronomic efficiency of the treatments. The study was conducted in Selvíria - MS, in a Latossolo Vermelho distrófico (Oxisol) under no-tillage system. The experimental design was a randomized block design with four replicates arranged in a 5 x 4 factorial scheme: 5 sources of N (P1 = organic polymer with 30% urea dissolved in water and 6.86% of N, P2 = Organic polymer with 70% urea dissolved in water and 19.35% of N, P3 = organic polymer with 30% dissolved urea and 9.65% of N, P4 = organic polymer with 70% dissolved urea and 11.00 % of N and U = urea with 45% of N) and 4 doses of N (0, 60, 120 and 180 kg ha-1). The sources of N did not differ for corn grain yield. However, at higher N rates applied (120 to 180 kg ha-1), the polymer P1 had the highest agronomic efficiency, although P2 have excelled with application of 120 kg ha-1 of N. The corn grain yield increased linearly with increase on applied N rates for polymers P1, P3 and P4 and up to the dose of 107 kg ha-1 N for the P2 polymer