EARLY POTASSIUM FERTILIZATION IN THE COVER CROP AND ITS RESIDUAL ON MAIZE SILAGE IN SUCCESSION

Abstract

This study aimed to evaluate the effects of the application of potassium fertilizer (K) on Urochloa ruziziensis cultivated in autumn/winter in the corn silage corn (Zea mays L.) cultivated in succession. A randomized block design was used. In the fall/winter the plots were constituted of U. ruziziensis and six doses of K (0, 30, 60, 90, 120 and 150 kg ha^-1) as muriate of potash (57% K₂O) and a fallow treatment. For the summer crop, the treatments were composed of silage corn and six doses of K₂O (120, 90, 60, 30, 0, and 0 (sowing and broadcast) kg ha^-1) complementary to the treatments applied to the fall/winter crop (totalling 150 kg K₂O ha^-1) and an additional treatment with recommended fertilization amount applied to the silage corn (60 and 90 kg K₂O ha^-1 at sowing and broadcasting, respectively). For U. ruziziensis, plant height, green and dry biomass yields and soil coverage were evaluated. For the corn silage, agronomic traits, leaf nutrient contents and green and dry biomass yields were evaluated. The advanced application of K fertilizer to U. ruziziensis did not alter its yields components or silage corn grown in succession; however, the complementary doses of 90 and 120 kg ha^-1 of K₂O promoted silage corn ears with larger diameters than those observed in the recommended fertilization.