Caracterização biofísica e potencial à intensificação sustentável da pecuária brasileira em pastagens

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2017-12-18

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Universidade Federal de Goiás

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Cattle ranching is the main land use activity in Brazil, with about 175 million hectares of cultivated pasture, with at least 50% of these being with some degree of degradation. Degraded pastures present low biomass production of little nutritional value, which leads to low animal weight gain in the rainy season and loss of weight in the dry season. Due to its low productive efficiency, if these areas were identified and recovered, they could be intensified, freeing pasture areas for other uses. In this context, the objective of this work was to evaluate the pasture vigor and the potential livestock intensification for Brazil. In order to obtain the vigor and productivity of Brazilian pastures, a Pasture Strength Index (PVI) was generated by integrating the α (intercept) and β (slope) coefficients, derived from the linear regression of the vegetation index (NDVI) over time (2000 to 2017). Pastures with low PVI values were located throughout the Caatinga biome, in the MATOPIBA region of the Cerrado biome, in the eastern portion of Mato Grosso do Sul, southeastern of Mato Grosso and northwestern of Goiás. These areas are associated to regions of higher water deficit, as shown by the relationship between the PVI and the total annual precipitation (R² = 0.40) and evapotranspiration. For the Cerrado biome, the PVI showed high spatial correspondence with the green biomass and percent green cover. Green biomass and percent green cover were generated from extrapolation of field data to the spatial resolution of MODIS images. The areas with lower PVI values in the Cerrado biome also had lower green biomass (< 6000 kg ha-1 ) and percent green cover (< 47%) during the growing season. Considering the accumulated green biomass in the growing season, it was observed that the Cerrado’s cattle stocking rate could increase from 1.11 AU ha-1 (real cattle stocking rate) to 2.56 AU ha-1 (potential cattle stocking rate). The real cattle stocking rate in 2015 was generated through the integration of the 2006 Livestock Census data with the Livestock Production data for the year 2015. The potential cattle stocking rate was obtained from the relationship between the forage production (green biomass and gross primary productivity - GPP) and the forage demand of one animal unit (1 AU = 450 kg). The potential of intensification was determined from the difference between the actual and the potential cattle stocking rates. For all of Brazil, the cattle stocking rate in 2015 was 0.97 AU ha-1 , reaching a potential of 3.60 AU ha-1 , that is, the potential for intensification was 2.63 AU ha-1 . The greatest potential of intensification occurred in the South region (3.62 AU ha-1 ), and the lowest in the North (2.13 AU ha-1 ) and Northeast (2.22 AU ha-1 ) regions of Brazil.

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ARANTES, A. E. Caracterização biofísica e potencial à intensificação sustentável da pecuária brasileira em pastagens. 2017. 136 f. Tese (Doutorado em Ciências Ambientais) - Universidade Federal de Goiás, Goiânia, 2017.