Resumen

LOPEZ-HERNANDEZ, Danilo; HERNANDEZ-VALENCIA, Ismael  y  GUERERE, Iraya. Physical, chemical and biological changes in the soil of a savanna protected from burning and cattle raising for twenty five years. Bioagro [online]. 2008, vol.20, n.3, pp.151-158. ISSN 1316-3361.

Burning of vegetation is a frequent management in Trachypogon savannas to eliminate dry pastures and stimulate the production of foliages with higher nutritional content. Burning of vegetation has also been considered a key factor to explain the origin and maintenance of savanna ecosystems, due to the changes produced on floristic composition and nutrient cycling. In order to determine the effects of fires and cattle raising on soil quality, we studied the changes in the top soil (0-15 cm) on selected physical, chemical and microbiological characteristics in an area under burning and cattle raising, and in another protected during 25 years. The results showed that in protected savannas soil fertility is higher due to less acid pH and higher contents of organic matter, exchangeable bases, organic and total phosphorus, and nitrogen, along with lower compaction and higher water holding capacity. Additionally, a higher microbiological activity due to a higher microbial C and N was observed.

Palabras clave : Fire; soil quality; microbial biomass; phosphatase activity.