Spatial variability of chemical indicators of Amazon agricultural soils through geomultivariate statistics, Brazil.

This work focuses on evaluating the spatial variability of chemical attributes of soils under different agricultural use and native forest, indicating which are the possible indicator attributes of changes in environmental, through the use and management of the soil. The study was carried out in the southern region of the Amazonas state, in an Argissolo Vermelho-Amarelo (Ultisol). Sampling grids were established measuring: 90 m × 70 m with regular soil collection spacing of 10 m for the guarana and forest areas; 90 m × 56 m spaced at 10 m × 8 m for annatto area; and 54 m × 42 m with spacing between points of 6 m for the cupuaçu area, totaling 80 sampling points in each area, with soil samples collected at depths of 0.

Soil chemical attributes in areas under conversion from forest to pasture in southern Brazilian Amazon.

The south of the Brazilian Amazon is one of the largest cattle-producing regions in Brazil, however, most of the pastures are in low fertility soils. Thus, cattle breeders compensate for the low production of pastures, increasing the size of the areas, generating more deforestation and burning. These practices increase the chemical degradation process of Amazonian soils, making them increasingly infertile when improperly managed.

Physical soil attributes in areas under forest/pasture conversion in northern Rondônia, Brazil.

The main cause of physical degradation in pasture areas is overgrazing, and when combined with poorly productive soils, it causes the loss of millions of hectares of agricultural soils a year. Thus, work is needed to indicate which physical attributes are most sensitive to degradation, generating information so that soil management can be proposed, with a view to economic, social, and environmental aspects. Therefore, the objective of the work was to evaluate the impacts caused on the physical attributes of the soil, in forests converted to pastures in northern Rondônia, Brazil.

Pedotransfer functions to estimate some soil properties in Indian Black Earth, south of Amazonas State.

Agriculture needs methodologies that assist in the determination of soil attributes and variability mapping attributes with greater levels of detail. Therefore, the objective of this research was to evaluate magnetic susceptibility as auxiliary variable for estimating soil attributes in areas of Indian Black Earths in the south of Amazonas State. Three Indian Black Earth areas are located in the municipalities of Apuí and Manicoré - Amazonas, under uses with coffee, cocoa and pasture.