CROPGRO-Perennial Forage model: parameterization of biological nitrogen fixation in Ipyporã brachiariagrass

Abstract

The intensification of forage-based animal production systems is often associated with the use of nitrogen (N) which is an essential nutrient for forage grasses. In a scenario of increasing production costs and increasing environmental pressures, biological N fixation through N-fixing bacteria is a sustainable and low-cost option for supplying N to plants. However, there are no culture models to simulate these scenarios with the contribution of bacterial inoculation as a source of N supply for forages. The objective of the present study is to parameterize and test the efficiency of the CROPGRO-Perennial Forage model to simulate the productivity of the Ipyporã brachiariagrass [Brachiaria spp. (syn. Urochloa spp.) cv. BRS331 Ipyporã] under the effect of bacterial inoculation. For this, data from an experiment performed at Embrapa Agrossilvipastoril in Sinop - MT, in a randomized complete block design, with four treatments applied in pastures of Ipyporã brachiariagrass, with three replicates: (1) without nitrogen fertilization (control); 2. fertilized with 80 kg N ha-1 yr-1; (3) inoculation with Azospirillum brasilense; (4) fertilized with 80 kg N ha-1 yr-1 + inoculant. Afterward, calibrations of the model will be carried out to simulate the pasture productivity for all the scenarios. The expected results are to construct parameterizations of the model with good efficiency in estimating the productivity of a hybrid of Brachiaria in monoculture and fertilized, managed under rotational defoliation, and to estimate the effect of the bacterial inoculation in these systems. (AU)