of organic matter. The subsoils are often reddish 
clay similar to those of the red and yellow soils of 
central Brazil. 
Predominant in the State of Rio Grande do Sul 
are the dark clay soils that are plastic and sticky, 
crack markedly on drying, and expand again on 
wetting. They are generally found on the flatter 
slopes and on much of the prairie area of the far 
south. Although the plastic clays are difficult to 
manage compared with the silts and silty clays, 
both groups of soils have a good potential for crop 
production under the proper management. 
CLIMATE 
The variety of climates in Brazil is chiefly due to 
wide differences in temperature and rainfall, which 
are influenced by such factors as elevation, pre- 
vailing winds, and distance from the Equator. 
Violent storms such as typhoons or hurricanes are 
nonexistent. 
The principal climatic regions include 
Fonte Boa 
Belem 
AVERAGE MONTHLY 
TEMPERATURE 
i AVERAGE MONTHLY 
PERCIPITATION 
JFM AMJ JAS OND 
Xanxeré 
NShl ie 
Pelotas E 
the humid-tropical in the Amazon lowlands: tropical 
in the coastal plains as far south as the 23d parallel 
of latitude; and subtropical through much of the 
Brazilian southermost 
States of Parana. Santa Catarina, and Rio Grande 
Highlands except in the 
do Sul, where the climate can be temperate. The 
Luzidnia 
Solvodor 
Sdo Paulo 
Figure 4.—Average annual precipitation. 
Boxes give average monthly precipitation and average monthly temperature at specified 
stations. 
4 FOREST RESOURCE REPORT 16, U.S. DEPARTMENT OF AGRICULTURE 
