Management of phosphorus fertilization with the use or non-inoculation with Azospirillum spp. in the culture of oats and in the corn with marandu grass consortium in no-tillage system

Abstract

The basic premise of no-tillage is based on three principles: the untilled soil, permanent cover and crop rotation. In this system, the correct choice of the plant species being used is extremely important, since it should be considered climatic factors characteristic of each area and type of soil. In the Cerrado, the climate is characterized by dry winter, high temperatures throughout the year coupled with rainfall impedes the deployment of cover crops and especially the permanence of straw on the soil surface. Thus, the grasses are of great potential in the maintenance of straw on the soil due to its high C/N and lignin content/N total, which slows their decomposition and increases the possibility of use in warmer regions such as the Brazilian Cerrado. In several regions of the world, reclamation, reduction of production costs and the intensive use of the area throughout the year, are being enabled by the crop-livestock integration (ILP) under no-tillage system, involving the cultivation of grains cultures or forage and livestock, generating results socio-economic and environmental impacts. In cerrado soils at low phosphorus availability coupled with its high rate of complexation are problems in the formation of pastures, since the element plays major role in the initial stages of plant life when they require high availability in the soil. This nutrient is essential for root development and tillering, past his disability to limit the productive capacity of pastures. Alternatively improving absorption of nutrients, bacteria diazotrofics stand out this possibility for action on root growth, and among the various genera Azospirillum can colonize the roots and stems of grasses. This is a promising alternative because these microorganisms may act in nutrient availability to the plant, besides the production of auxins, substances responsible for stimulating growth, reducing the use of synthetic fertilizers on crops. Therefore, the research will aim at a Oxisol under irrigated conditions in the Cerrado, evaluate: 1) the effect of phosphorus fertilization and the inoculation with Azospirillum spp. in oat seeds on their nutrition and dry matter yield of shoots and roots, 2) evaluate the residual effect of phosphorus fertilization and oat straw decomposition on growth and yield of corn with and without inoculation by Azospirillum spp. and Marandu grass intercropping, and 3) the period after simulating the fence of the pasture (60 days after the corn harvest), evaluating the chemical and nutritional quality of Marandu grass, straw and its effect on production components commonbean yield and Winter in succession. (AU)