Saturday, 15 July 2006

Effect of Lignite Fly Ash Application on the Amount of Certain Heavy Metals in Lychee Orchard's Soils of Northern Thailand.

Jiraporn Inthasan1, Niwat Hirunburana2, Ludger Herrmann3, and Karl Stahr3. (1) Dept of Soil Resources and Environment, Faculty of Ag Production, Maejo Univ, Prao Road, Sansai, ChiangMai, 50290, Thailand, (2) Dept of Soil Science and Conservation, Faculty of Agriculture, Chiang Mai Univ, ChiangMai, 50200, Thailand, (3) Institute of Soil Science and Land Evaluation, Hohenheim Univ, Stuttgart 70599, Stuttgart, Germany

On the purpose of affording to use lignite fly ash, a waste product of the electrical power plant at Mae Mau in Lampang province of northern Thailand as a soul amendment improving up land soil properties and increasing the qualities and ability of bearing fruits in litchi trees, two splits of 1.0 kg/tree/year were applied during 2002 to 2004 by broad-casting of 8 X 8 m. under the canopy of plants. This experiment was conducted in 3 locations on the slope complex of Ultisol soils at Pong Yang, Mae Rim district about 35 km. north of Chiang Mai province, Thailand. Soil samples were collected after harvesting period at pre-application in 2001 and the end of the experiment in 2004. Only two depths of 0-0.1 m and 0.1-2.5 m composite soils were brought for investigating accumulations of certain heavy metals such as Pb, As, Ni, Co, Cd and Al using HNO3 (conc.): 30%HCl extract with the exception of Al, 1 N of KCl being preferable. Generally, the lignite fly ash applications had effects on the added amounts of most heavy metals in soil of 0-0.25 m ranging 11.0-34.3 %Pb, 9.2-45.7 %As, 16.7-28.9 %Ni and 10.8-13.1 %Co. Only Cd was not increased except one location was found 14.6% higher. The most dramatic result was extractable Al, which was effected by both the chemical fertilizer and lignite fly ash applications. However, the amount of extractable Al according to the fly ash incorporation was greater up to 76-104 ppm in the sub soil of 0.1-0.25 m. The results bring to the attention of the lower pH level in soils under the lignite fly ash application. Keywords: Lignite fly ash, soil amendment, heavy metals.

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