Properties of Several Fly Ash Materials in Relation to Use as Soil Amendments

Abstract

Fly ash samples from five power stations in Western Australia and Queensland, and two soils used for horticulture in Western Australia, were evaluated for a series of physical and chemical properties. Soils were comprised primarily of coarse sand-sized particles, whereas most of the fly ashes were primarily fine sand- and silt-sized particles. Hydraulic conductivities in the fly ashes were 105- to 248-fold slower than in the soils. The water-holding capacities of fly ashes at "field capacity" were three times higher than those of the soils. Extractable P in the fly ashes (except Tarong and Callide) were 20- to 88-fold higher than in the soils. The pH showed considerable variation among the different sources of fly ash, with samples from Muja being the most acidic (pH = 3.8; 1:5 in CaCl2 extract) and from Gladstone the most alkaline (pH = 9.9). The toxicity characteristic leaching procedure (TCLP) values indicate that the potential for release of trace elements from the fly ashes was well below regulatory levels. When applied at sufficient rates (e.g., to achieve 10% w/w in surface layers) to sandy soils, fly ash altered texture and increased water-holding capacity. Depending on the source of fly ash used, such amendments could also provide P and aid nutrient retention by increasing the phosphorus retention index (PRI) and/or cation exchange capacity (CEC). The considerable variability in physical and chemical properties among the fly ash samples evaluated in the present study supports the notion that field trials are essential to the future development of soil amendment strategies making use of any particular source of fly ash.

Nitrogen Increases Evapotranspiration and Growth of a Warm‐Season Turfgrass

“…The soil at the site is known locally as Karrakatta sand (McArthur and Bettenay, 1960), or is classified as a Dystric Xeropsamments using soil taxonomy (USDA, 1992). The surface soil (0–150 mm) has a pH of 4.7 (1:5 soil: 0.01 M CaCl 2 extract), electrical conductivity of 0.01 dS m −1 (1:5 soil/water extract), cation exchange capacity of 3.22 cmol (+) kg −1 , C concentration of 6.5 mg g −1 , and N concentration of 0.4 mg g −1 The subsurface soil (>150–1000 mm) has on average a pH of 5.6, electrical conductivity of 0.003 dS m −1 , cation exchange capacity of 1.33 cmol (+) kg −1 , C concentration of 0.9 mg g −1 , and N concentration of 0.2 mg g −1 The surface soil contains 92% coarse sand, 2% fine sand, 2% silt, and 4% clay (Pathan et al, 2003).…”

Assessment of trace element impacts on agricultural use of water from the Dan River following the Eden coal ash release

“…Coal ash has been studied in the past for use as a soil amendment to improve soil texture and water holding capacity of sandy soils, to increase cation exchange capacity (CEC), and to supply lime, P, K, and Ca when applied at appropriate rates. For these evaluations, coal ash was applied at rates ranging from 10 to greater than or equal to 100 tonnes/ha, depending on desired changes in pH, nutrients, or physical properties (Plank et al ; Pathan et al ). From that perspective, infrequent additions of 2.2 tonnes ash/ha with flooding should have minimal negative impacts on agricultural soils in the Dan River basin.…”

Effectiveness of Cultural Thatch‐Mat Controls for Young and Mature Kikuyu Turfgrass

“…The soil is free‐draining and has a low chemical fertility. The surface soil (0–150 mm) has a pH of 4.7 (1:5 soil: 0.01 M CaCl 2 extract), electrical conductivity of 0.01 dS m −1 (1:5 soil/water extract), cation exchange capacity of 3.22 cmol (+) kg soil −1 , C content of 6.5 mg g −1 and N content of 0.4 mg g −1 The subsurface soil (>150–1000 mm) has a pH of 5.6, electrical conductivity of 0.003 dS m −1 , cation exchange capacity of 1.33 cmol (+) kg −1 dry soil, C content of 0.9 mg g −1 and N content of 0.2 mg g −1 The surface soil contains 92% coarse sand, 2% fine sand, 2% silt, and 4% clay (Pathan et al, 2003).…”