Characterization of fertility and particle size of Varzea soils of Mato Grosso and Mato Grosso do Sul States of Brazil

The states of Mate Grosso and Mate Grosso do Sul of Brazil have large lowland soils, locally known as ''Varzea'', and the major part of this area is not used for agricultural purposes. The present study was undertaken at the National Rice and Bean Research Center, Goiania-Goias, to characterize the fertility and particle size of lowland soils of these states. Soil samples were collected at depth intervals of 0-20 cm, 20-40 cm, 40-60 cm, and 60-80 cm at 14 locations in the two states. Organic matter contents and pH averaged 46 g/kg and 5.2 in the surface 20 cm of soil. Phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) contents were adequate for annual crop production in the 20-cm soil layer. However, iron (Fe) content in some of the samples was high and manganese (Mn) content pas lower than critical level under well-drained soil conditions. In almost all soil samples analyzed, aluminum (Al) content was higher than 1 cmol/kg, and Al saturation was also higher, especially for legume crops. In general, base saturation was lower in these soils. A large part of these samples has clay loam texture which is considered appropriate for annual crop production.