Resumo

HEPPER, Estela; URIOSTE, Ana; BELMONTE, Valeria  e  BUSCHIAZZO, Daniel. Impact of different burning temperatures on the physical and chemical properties of Central Semiarid Pampa soils. Cienc. suelo [online]. 2008, vol.26, n.1, pp.29-34. ISSN 1850-2067.

The natural and controlled burns are very frequent in the Caldenal area, located in the Central Semiarid Pampean Region, and the effects they produce on the physical and chemical properties of the soils are not well-known. The aim of this study was to find out the burning temperatures that produce changes in soil physical and chemical properties in the Caldenal area. Two Entic Haplustolls (loam and sandy loam), were heated during 5 minutes at 100 ºC, 200 ºC, 300 ºC, 400 ºC, 500 ºC and 600 ºC. Ph in water, texture, organic carbon, total nitrogen, exchangeable cations and cation exchange capacity were determined on soil samples that received heat and on untreated controls. The 500 and 600 ºC burning temperatures produced more changes, decreasing the organic carbon contents, total nitrogen, the OC/Nt ratio, the cation exchange capacity and causing the transformation of the loam soil into sandy loam and of the sandy loam into loamy sand soil. The exchangeable potassium and sodium contents increased with burning temperatures of 300 ºC and 400 ºC and greater, depending on the soil, but in both of them the magnesium content decreased from 400 ºC and greater, and the calcium content was not affected by high temperatures. At lower temperatures, such as 200 ºC and 300 ºC, only the proportions of sand fractions changed. As a consequence of burning with high temperatures, the water and nutrient retention capacity of the Caldenal area soils will decrease, concomitantly with the fertility.

Palavras-chave : Soil temperature; Organic carbon; Total nitrogen; Texture; Cation exchange capacity.

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