Production systems and weed control in annual crops of the Cerrado area of the State of Piaui

The aim of this study was to evaluate the contribution of the use of cover crops, under direct planting and a conventional system, on crops of soybeans, maize and rice in the Cerrado area of the State of Piaui, Brazil (PI). The experiment was carried out during the agricultural years of 2010/2011 and 2011/12, from October 2010 to April 2012, in the Serra do Quilombo, on the Celeiro Farm in Bom Jesus, PI. The design was of randomised blocks in split lots. Soil management systems of conventional tillage and direct planting were evaluated in the lots, and five systems of annual-crop production (soybeans, maize and rice) and cover plants in the sub-lots. Due to the production of phytomass from the overseeding of Urochloa ruziziensis and Pennisetum glaucum in the soybean, and by Urochloa ruziziensis being sown intercropped with the maize, the system of direct planting resulted in significant reductions in the emergence and dry matter accumulation of weeds prevalent in the area (Spermacoce latifolia, Chamesyce hirta, Amaranthus viridis, Digitaria sanguinalis and Cenchrus echinatus).