Antecipation of potassium fertilization during the cultivation of cover crops, aiming to grow corn in succession

Abstract

Because it has superior quality when compared to other species, corn is considered one of the best plants for ensiling. However, when corn is destined for silage, the entire aerial part of the plant is removed from the area, which results in a lack of nutrient cycling, especially potassium (K), present in large quantities in plant remains. Therefore, the objective of this work was to evaluate the effect of different doses of K applied in advance to the cover crop grown during fall/winter on its yield components and on the productivity of corn silage grown in succession. In a randomized block design, in the fall/winter harvest, the plots were composed of millet (paper 1) and brachiaria ruziziensis (paper 2) and six doses of K (0, 30, 60, 90, 120 and 150 kg K2O ha-1) as potassium chloride (57% K2O) in addition to a fallow treatment. In the summer harvest, during corn cultivation, six doses of K2O were applied, complementary to the doses applied in the fall/winter harvest, totaling 150 kg K2O ha-1 (120, 90, 60, 30, 0) and 0 kg K2O ha-1 for the treatment that received 150 kg K2O ha-1 during fall/winter. An additional treatment cultivated under fallow, which received the recommended fertilizer dose (60 and 90 kg ha-1 of K2O in furrow and broadcasting, respectively). For cover crops, plant height, green and dry biomass yields and soil coverage by straw were evaluated. For corn silage, agronomic traits, leaf nutrient content and green and dry biomass yields were evaluated. The doses of K applied in advance did not change the yield components of the cover crops. However, the dry biomass produced was sufficient for good soil coverage. When cultivated after brachiaria ruziziensis, complementary fertilization of 90 and 120 kg ha-1 of K2O increased the corn ear diameter in relation to the recommended fertilization. Potassium fertilization applied in advance to millet and brachiaria ruziziensis cultivated in fall/winter in soils with high potassium content does not alter the nutrient content present in the leaves and the productivity components of corn silage grown in succession.