Impact of Fly Ash Amendment and Incorporation Method on Hydraulic Properties of a Sandy Soil

Authors: Gangloff W.J.¹; Ghodrati M.²; Sims J.T.³; Vasilas B.L.³

Source: Water, Air, and Soil Pollution, Volume 119, Numbers 1-4, April 2000 , pp. 231-245(15)

Publisher: Springer

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Abstract:

Coal fly ash has physical and chemical characteristics that make it useful as a soil amendment, one of the more important being the potential to permanently improve the soil water relations of sandy, drought-prone soils. We axemined changes in the infiltration rate and water holding capacity of a sandy soil after application of high rates (up to 950 Mg ha^-1) of a Class F fly ash. Fly ash was applied to large field plots by either conventional tillage (CT; moldboard plow-disk) or intensive tillage (IT; chisel plow-rotovate-disk), and to microplots using a rototiller. Infiltration rate (i) was measured in both studies with a disk permeameter on three occasions over a 12-month period. Ash effects on gravimetric water content ( thetas _g) at the 0–40 cm soil depth were measured during a 168 hr period following a 2.5 cm rainfall event and water release curves (33 to 500 kPa) were constructed in the laboratory using soils from the large plots. In both studies i was decreased by sim 80% one year after addition of fly ash and thetas _gin ash-amended soil was higher than unamended soil throughout the 168 hr monitoring period. Soil water distribution varied with tillage; the IT treatment had the highest thetas _g increases in the 0–20 cm depth while the CT treatment had thetas _gincreases throughout the 0–40 cm depth. Soil water content and distribution in ash-amended microplots were similar to IT treatments. Fly ash amendment not only increased water holding capacity but also increased plant available water by 7–13% in the 100–300 kPa range. These results suggest fly ash amendment may have the potential to improve crop production in excessively drained soils by decreasing i and increasing the amount of plant available water in the root zone.

Keywords: fly ash; infiltration rate; incorporation method

Language: English

Document Type: Regular paper

Affiliations: 1: Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523 2: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720 (author for correspondence, e-mail: ghodrati@nature.berkeley.edu) 3: Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19717–1303

Publication date: 2000-04-01

Impact of Fly Ash Amendment and Incorporation Method on Hydraulic Properties of a Sandy Soil

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