Page 492 - FRUTAS DEL TRÓPICO

492 Frutas del trópico

grown on these soils often show aluminum toxicity, nutrient deficiency, especially P. However,
Oxisols can be productive with proper nutrient management, especially using lime.

Table 1. Major soils in tropical region.

Area Fertility problem
Soil order % of Tropics
(x1,000 km )
2
Poor fertility, Al toxicity, Low CEC, Low
Oxisols 9,586 27.54
organic matter, P deficiency
Relatively poor fertility, Al toxicity, Low
Ultisols 7,611 21.87
CEC, Low organic matter, P deficiency
Inceptisols 6,068 17.43 Various fertility, Can be fertile
Alfisols 4,803 13.79 Good soils for crop production

Often poor nutrient and water holding
Entisols 4,318 12.40
capacities, some soils very fertile

Ultisols are the second most common soils in the tropics with 7.6 million km (21.87%
2
of the tropics). The ‘red clay’ soils of the southeastern United States are examples of Ultisols.

They have less than 10% weatherable minerals in the surface soil, and have less the 35% base

saturation throughout the soil. Typically Ultisols are red to yellow in color and are acidic, often

having a pH of less than 5. The red and yellow colors result from the iron oxide. Major nu-

trients, such as calcium, phosphorus and potassium, are typically deficient in Ultisols. Nutrient

management is important for crops grown on these soils.
Alfisols occupy about 13.79% tropics are moderately leached with a greater than 35%

base saturation. In the US, they account for ~13.9% of the land area. These soils are high in

calcium, magnesium and potassium. The combination of generally favorable climate and high

native fertility allows Alfisols to be very productive soils for agricultural use in tropics.

Universidad Autónoma de Chiapas