Residual da adubação nitrogenada na sucessão milho-capim sudão

Abstract

In agriculture, nitrogen fertilization is one of the most relevant costs when dealing with modern agriculture, since in addition to being required in high quantity, may has a low efficiency due to physical and biochemical processes, which means that this nutrient is not absorbed in its fullness. The objective is to study methods that increase efficiency, making natural and financial resources more effective, reducing environmental impacts and increasing the profitability of the agricultural production system. In this case it was decided to evaluate how the succession management of crops can contribute to the system. It was carried out in a completely randomized design in a greenhouse. Five treatments (0; 50; 100; 150; 200%) of the recommended dose of nitrogen (N) were determined for vessel with 4 replicates. The experiment was divided in two cycles, the first one was made with corn where the treatments were applied and the second the sudangrass after incorporation of the drymatter produced by corn. The corn was evaluated for symptoms of nutritional disorders, weight of a thousand grains, number of grains per plant and productivity, while in the sudangrass, dry matter, plant height and Naccumulation were evaluated in the plant. In corn plants, symptoms of deficiency were observed at doses of 0% and 50%, the weight of a thousand grains did not differ, however, the number of grains per plant and productivity presented a significant difference, where the maximum technical efficiencies were at the doses of 127% and 123%, that is, 381 mg dm-³ and 369 mg dm-³, respectively. In the sudangrass crop all variables differed statistically, where the plants reached the highest height in 118% of the dose, dry matter in 146%, however, the accumulation of Nto the regression was linear, that is, with the increase of the dose of fertilizer increases the accumulation. With the data obtained it is concluded that the recommendation to increase the efficiency of the Nfertilization is 123% of the dose to pot, because it reaches the highest grain yield of the crop, in addition, it is reached in the sudangrass dry matter production of 13,8 g pot-¹, yield index for forages. However, long-term future studies should be carried out to evaluate the succession of nutrient cycling and culture management, which will influence their growth and development.