Effect of nitrogen over corn-grass association in the renovation of pastures at piedmont of the Llanos Orientales of Colombia

In the piedmont of the Eastern Plains of Colombia, was established the association of corn with the grasses B. decumbens, Mulato and Toledo, to renovate degraded pasture. The effect of the N was evaluated with 100 and 200 kg ha-1 applied to the corn to the 15 and 35 days after the sowing (das). The available N in the soil in nitrate form remained N in 42 and 43 kg ha-1 to the 15 and 35 das respectively, coinciding with the fertilization of N applied to the corn, but to the 60 days it reducing to 11.9 kg N ha-1. The available N in ammonium form was of 82, 84 and 72 kg ha-1 to the 15, 35 and 60 das, respectively. To the beginning of the flowering, the N leaf in the corn associated with B. decumbens and with the grass, Toledo was respectively of 2.9 and 2.83%, while in the association with grass Mulato was of 2.66%. The N leaf in the grasses Mulato and Toledo was respectively of 3.31 and 3.20%. In the phase of filled grain of corn, the N leaf in the corn didn’t present significant differences when being associated with the three grasses, being obtained an average of 2.59%. The treatments with 100 and 200 kg N ha-1 applied to the corn didn’t affect the content of N in the leaves of corn and grass, so much in the moment of the flowering like in the one filled of the grain.