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 und ertaken at the National Rice and Bean Research Center, Goiania-Goias, to characterize the fertility and particle size of lowland soils of th ese 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. O rganic 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 cro p production in the 20-cm soil layer. However, iron (Fe) content in so me of the samples was high and manganese (Mn) content pas lower than c ritical level under well-drained soil conditions. In almost all soil s amples 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 samp les has clay loam texture which is considered appropriate for annual c rop production.