CLASSIFICATION OF PASTURE DEGRADATION LEVELS IN TERMS OF HYDRIC EROSION RISK IN QUARTZIPSAMMENTS AREAS AT ALTO TAQUARI WATERSHED (MS/MT, BRAZIL)

Resumo

Pasture degradation is currently one of Brazil.s agriculture main problems. Pasture areas grown on Quartzipsamments (RQ) at the Alto Taquari watershed (BAT) are important sources of sediments which intensify the Taquari river.s siltation in Pantanal. The objective of this work was to assess the use of the Linear Spectral Mixture Model (LSMM) in the mapping and characterization of the current degradation level of pastures planted on RQ at BAT in terms of erosion risk. Using Landsat 5 satellite images of 2010 and employing the LSMM, we generated an image for exposed soil (ES), which was used along with field work to define three pasture degradation levels: low degradation level or not degraded (ES ≤20%), medium degradation level (20% < ES ≥45%) and high degradation level (ES > 45%). In 2010, the pastures grown on RQ at BAT encompassed a total of 851,204 ha, which corresponded to 66.3% of this soil class and to 30.1% of the watershed surface. The largest amount of pasture areas, around 57%, showed medium degradation level, about 9% showed high degradation level, and the remainder, around 34%, were pastures with low degradation level or not degraded