Weed community dynamics in a cover crop / silage maize succession crop system

Resumo

The objective of this study was to evaluate the weed community in an Urochloa ruziziensis / silage maize (Zea mays L.) succession system in which the cover crop received potassium (K) fertilizer. In the fall/winter growing season, treatments were U. ruziziensis and six doses of K (0, 30, 60, 90, 120 or 150 kg K₂O ha^-1) as muriate of potash (KCl) in addition to fallow. In the summer season, maize was cultivated with doses of K, complementary to the fall/winter season to total 150 kg K₂O ha^-1: (i.e., 120, 90, 60, 30, and 0) and 0 kg K₂O ha^-1 for fallow. The previous fallow treatment received the recommended K fertilization (60 and 90 kg ha^-1 of K₂O at planting and at maize sidedressing, respectively). A weed population survey was carried out using a 0.50 cm square. Their phytosociological indices, dry mass, number and total density of species was calculated. The weed community and its phytosociological indices are altered as a result of the growing season and crop. Weed dry mass is higher before cutting the U. ruziziensis. The number of species and plant density is higher at the V₄ maize growth stage before applying the herbicide.