Environmental Diagnosis of Degraded Pasture Areas and Soil Chemical Quality

The extensive grazing system is predominant in Brazilian livestock. The lack of adequate management in these areas hinders the performance of the activity and can bring problems related to the environmental degradation of pastures. Therefore, our objective was to perform environmental diagnosis in pasture areas on the Belo Horizonte farm, in the municipality of Dueré-Tocantins in northern Brazil. The environmental diagnosis was made in three pastures composed of Urochloa brizantha cv. Marandu (pasture 1, pasture 2 and pasture 3) in the rural property of Belo Horizonte, municipality of Dueré -Tocantins. Degradation was evaluated by the following methods: (a) structured interview of questionnaire to evaluate pasture formation, degradation, recovery and maintenance; (b) soil sampling of 0-20 cm layer and (c) visual assessment of the level of environmental degradation. Regarding the first method, the owner reported that the greatest difficulty in adopting conservation pasture practices was the high cost of implementation, which caused only a few practices to be performed. The soil analysis demonstrated that nutritional parameters were lower than the reference values adopted. In the third method, the five parameters: vigor and pasture quality; invasive plant population; soil cover; erosion were evaluated. In the use of these five parameters for evaluation, the individual results were established for each parameter, which ranges from 1 to 4. Only pastures 1 and 3 are in a state of degradation at different levels, ‘strong’ and ‘light/mild’, respectively. Reduced soil fertility was found to be one of the causal agents of pasture degradation. Pasture degradation is related to the reduction of soil chemical attributes, such as phosphorus (P), nitrogen (N) and high aluminum (Al) saturation.