Dados do Trabalho

Título

IN WHAT SOIL TEXTURE CLASSES ARE THE BRAZILIAN PASTURE AREAS INSTALLED?

Resumo

Pasturelands cover about 172 million ha of Brazil and many of these areas are in conditions of degradation. Therefore, it is necessary to know the characteristics of the soils used for pasture in Brazil. This work aimed to evaluate the suitability of pasture areas in terms of soil texture using geotechnologies in Brazilian biomes. For that, we established two depths (0-20 and 80-100 cm) to map the clay content in the soil using the Random Forest machine learning algorithm. For modeling, we based on a synthetic image of exposed soil obtained by the GEOS3 algorithm that uses the historical series of the Landsat satellite (1984-2018) and in 40,000 samples of clay content extracted from the Brazilian Soil Spectral Library database. The Mapbiomas service was the source of the pasture and biome polygons. There were strong correlations between the predicted and measured covariates, reaching R2 of 0.67 for 0-20 cm layer and 0.60 for the 80-100 cm layer. We mapped 149,559,028 ha of pasture, in wich 34% were on sandy soils; 22% on medium-sandy; 22% on medium-clayey soils and 19% on clayey soils. Considering the subsurface layer, 4% of pasture areas were on sandy soils; 24% on medium-sandy; 28% on medium-clayey soils and 42% on clayey soils. These results suggest that in Brazil, 42% of the areas cultivated with pasture are on soils with a textural gradient, with high natural fertility but a high risk of erosion. On the one hand, 76% of the pastures in the Amazon region are on soils with high productive potential, medium clayey and clayey, reaching 95% if we consider the 80-100 layer. On the other hand, in the Caatinga, this crop is located in sandy areas (about 82%). The results raise the debate about which soils are degraded areas and whether areas with agricultural potential should be maintained with this crop. Such information can direct public policies and guide decision-makers regarding this non-renewable natural resource's conservation or sustainable exploitation.

Palavras-chave

Remote Sensisng; Soil Health; Soil Quality.

Instituição financiadora

University of São Paulo

Agradecimentos

The authors thanks to GeoCis Research Group for sampling and analyses.

Área

Divisão 3 – Uso e Manejo do Solo: Comissão 3.4 – Planejamento do Uso da Terra