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7305010 
Journal Article 
Wood-ash composition and soil-pH following intense burning 
Ulery, AL; Graham, RC; Amrhein, C 
1993 
1 
Soil Science
ISSN: 0038-075X
EISSN: 1538-9243 
156 
5 
358-364 
English 
WOS:A1993MH42900008 
Thousands of hectares of wildlands are burned annually in the western United States. The composition and mineralogy of wood-ash produced by severe burning, and the changes in pH of soils underlying the ash, were examined at five sites in Califor-nia. Soil pH increased by as much as 3 pH units (to pH 10.5) immediately after burn-ing compared with unburned soil. Approx-imately 1 to 2% of each burn area was affected to a maximum observed depth of 20 cm. The major component of fresh, white wood-ash is calcite, while K and Na carbonates are present in minor amounts. The initial very high pH values of wood-ash and surface soil are caused by K and Na oxides, hydroxides, and carbonates. These compounds are very soluble and do not persist through the wet season. The calcite is much less soluble and was present in soils 3 years after burning, maintaining moderately alkaline pH in surface soils that are normally neutral to strongly acid. 
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