Título ATIVIDADE MICROBIANA EM SOLO CULTIVADO COM MILHO EM ÁREA COM DIFERENTES COBERTURAS VEGETAIS ANTECESSORAS.

Abstract

Soil microbial attributes, besides being important bioindicators used in monitoring environmental changes, can also guide the planning and management to be adopted in a given agricultural activity. Thus, the objective of this work was to evaluate soil microbial activity in an area cultivated with corn, which received different preceding cover crops. The experiment was established in a no-till system, with soybean/corn rotation. A randomized complete block design was used with nine treatments and three replications. The treatments consisted of the cover crops sorghum (Sorghum bicolor), sunn hemp (Crotalaria ochroleuca), pearl millet (Pennisetum americanum), Urochloa ruziziensis, piatã grass (U. brizantha cv. Piatã), forage radish (Raphanus sativus L.), brizantha grass (U. brizantha cv. Xaraés), pearl millet + forage radish, and fallow. The corn crop was established over the cover crops in the 2019/20 harvest season. The corn crop plots consisted of five rows of five meters in length. Corn growth characteristics, soil carbon, and microbial respiration were evaluated. The highest values for soil carbon were obtained in the pearl millet (12.75%) and U. ruziziensis (11.87%) covers. Pearl millet also reached the highest value for microbial respiration (7.75 mg C-CO2 100 g soil-1). The greatest corn plant height was achieved in the piatã cover, with 2.82 m. The covers with piatã and U. brizantha provided the largest stem diameter, with 23.43 and 22.41 mm, respectively. The greatest first ear insertion height was observed for the piatã and U. ruziziensis covers. It was concluded that cover crops influence soil carbon and microbial activity, with pearl millet being the cover that provides the highest microbial respiration. Corn growth characteristics were favored by Brachiaria cover crops.