Plantas de cobertura como facilitadoras do cultivo de milho em sistema de plantio direto orgânico

Abstract

Cover crops can act as facilitators for the production of maize (Zea mays L.) in an organic no-tillage system. The mixture of species and/or isolated cultivation, mainly of legumes, can increase the availability of nitrogen (N) and phosphorus (P) for maize in succession. The aim of this study was to evaluate the potential of cover crops, isolated and in a mixture (mix), on N and P dynamics in the soil, mineral nutrition, and maize production in an organic no-tillage system. The experimental design was a randomized block design with 5 replications and 4 treatments: (1) Mix - Crotalaria ochroleuca, dwarf pigeon pea (Cajanus cajan, L. Millsp.), pearl millet (Pennisetum glaucum, L. R. Brown), and buckwheat (Fagopyrum esculentum Moench), (2) pearl millet, (3) C. ochroleuca, and (4) fallow/spontaneous vegetation. The green and dry mass production, lignin content, and macronutrient accumulation were evaluated in the cover crops. In the soil, ammonium, nitrate, available phosphorus (P) levels, and the activity of acid and alkaline phosphatase enzymes were assessed. For maize, chlorophyll index, foliar macronutrient content, and grain yield were evaluated. C. ochroleuca contributed to the supply of N (ammonium and nitrate) in sync with maize demand, and despite not increasing foliar N levels, it provided the highest maize grain yield. The inclusion of cover crops recognized for their efficiency in P absorption from the soil, such as dwarf pigeon pea and buckwheat, increased P accumulation in the dry mass of the mix. However, it did not increase soil P levels during the maize cycle sown in succession.