Silagem de milho cultivado em consórcio com Urochloa brizantha cv. marandu em diferentes estratégias de controle de plantas infestantes

Abstract

The increase in global demand for food has demanded the adoption of innovative technologies such as Crop-Livestock Integration (CLI), which has been indicated as a profitable and sustainable alternative for food production in the Cerrado region. The adoption of intercropped grass and corn crops can occur without interference between species. The strategy of using selective herbicides for corn crops intercropped with tropical grasses, in subdoses, has been used to temporarily “stop” the grass, so that it does not stand out in competition with the main crop. In this sense, a field trial was carried out in Uberaba MG to evaluate different strategies for managing weeds in the CLI system in conventional sowing, where corn was intercropped with marandu grass. The experiment was conducted in a systematic design, with randomization of sampling units, consisting of three control strategies: T1 – Application of 2.0 kg ha-1 of active ingredient (a.i.) atrazine (equivalent to 100% of the recommended atrazine dose in leaflet) in the V1 stage of corn cultivation; T2 – Application of 2.0 kg ha-1 a.i. of atrazine plus 0.013 kg ha-1 a.i. of nicosulfuron (equivalent to 25% of the dose of nicosulfuron recommended in the leaflet) in corn V4 stage; and T3 – Application of 0.5 kg ha-1 a.i. of atrazine and 0.05 kg ha-1 a.i. of mesotrione (equivalent to 50% of the dose of the formulated mixture recommended in the leaflet) at the V4 stage of the corn crop; and the controls T4 – ILP system without application of any herbicide and T5 – corn crop in monoculture, sown without soil disturbance for more than 8 years with application of 2.0 kg ha-1 a.i. of atrazine in stage V1 and 2.73 ha-1 a.i. of glyphosate at the V4 stage in corn. The different weed control strategies did not alter the microbiological quality and productivity of plant biomass in the silage pre-harvest, while the application of nicosufuron plus atrazine and the application of mesotrione plus atrazine provided the highest dry matter contents. Subdoses of the products nicosulfuron and mesotrione, as well as atrazine in CLI were effective in reducing the population of weeds in the first 30 days after application, but reduced the dry matter of marandu grass at 165 days after harvest to the detriment of single atrazine. CLI without herbicide application was more effective in controlling the weed plant than the application of atrazine plus glyphosate in the monoculture and direct seeding system.