Resumo

RINCON, Álvaro  e  LIGARRETO, Gustavo A.. Fertility and extraction of nutrients in corn-grass association in acid soils of the Piedemont Plains of Colombia. Agron. colomb. [online]. 2008, vol.26, n.2, pp.322-331. ISSN 0120-9965.

In an oxisol of the Research Center La Libertad of Corpoica located at 17 km of Villavicencio, the corn association with grass B. decumbens, 'Mulato 1', and average 'Toledo' was established for recovering the productivity of degraded grassland. The minerals applied in kg·ha^-1 at 45 day before sowing time by hectare were 55 Ca, 88 Mg, 35 P, and 45 S using as a source dolomite lime, phosphoric rock and agricultural gypsum. At the sowing time, it was applied 31 P, 27 N (source diamonic phosphate), 37.5 K (source potassium chloride), 3 Zn; 0,1 Cu; 0,5 B and 1,2 S (source boronzinc). Up to the 15 day after sowing time (das) it was applied 37,5 K. Nitrogen was applied in dose of 100 and 200 kg·ha^-1 at 15 and 35 das. The soil analyses realized after the crop of corn demonstrated an improvement of fertility because the saturation of bases increased from 24% initial to 47%, available phosphorus increased from 2 to 11.8 ppm and sulfur increased from 3 to 6 ppm. In the moment of harvest, the highest extraction of N was carried out by corn grain and grass with 43 and 45 kg·ha^-1 respectively, whereas P appeared in highest concentration in corn grain with 12.7 kg·ha^-1. The grass and soca of corn (stems and leaves after the harvest) were characterized having the highest content of K with 40 and 27 kg.ha^-1, respectively. Ca, Mg and S were more extracted by the grass with 9, 8 and 6 kg·ha^-1, respectively. The highest extraction of minerals by the corn and grass were the N, P and K with 91, 57 and 58%, respectively, whereas those of smaller extraction were Ca with 2.2% and Mg with 16%.

Palavras-chave : associated cultures; minerals; forage; production; degraded grassland.

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