8153

• UCREFRP Catalog Number: 8153
• Author: Jacobs, e. L. W.
• Title: Editor
• USFW Year: Series
• USFW - Doc Type: 1989
• Copyright Material: YES

40 MAYLAND ET AL.
Bioavailability of Fly Ash Selenium
Approximately 26 to 33 x 109 kg fly ash were generated annually in
the USA between 1975 and 1980 (Combs et al., 1980; Furr et al., 1976a).
Some of this fly ash has been used as a soft aggregate in construction appli-
cations and as filter aids in processing municipal sewage. Because these ap-
plications consume only a small fraction of the total production, its possible
use in agriculture has been investigated.
Fly ashes vary greatly, not only in particle size and elemental composi-
tion, but also in pH (Furr et al., 1977). Use of these ashes as soil amend-
ments could affect the availability of Se and other elements, both in the ash
and in the soil, and should be carefully evaluated. The pH of the ash, con-
centration of total soluble salts, and presence of elements toxic to plants are
factors that affect growth and elemental concentration in the plant.
Several studies have shown that at least a portion of the Se in fly ash
is available for uptake by plants grown naturally or experimentally on fly
ash or on soils amended with fly ash (Combs et al., 1980; Furr et al., 1976a,
1978; Gutenmann et al., 1979; Stoewsand et al., 1978). Furr et al. (1976a)
found that the amount of Se absorbed by the edible portion of several vegeta-
bles was proportional to the amount of coal-derived fly ash amendment added
to the soil. In that study, the plants absorbed less Se during the second crop-
ping than during the first. In another study (Gutenmann et al., 1979), the
Se in fly ash was steadily released over five successive cuttings of alfalfa,
birdsfoot trefoil (Lotus corniculatus L.), bromegrass, orchardgrass, and
timothy.
Agricultural uses of refuse-incinerator fly ash may be more restricted
than those for coal-derived fly ash. For example, the incinerator fly ash used
in a study by Wadge and Hutton (1986) not only contained 4.3 mg Se/kg
but also had high concentrations of Cd (450 mg Cd/kg) and Pb (8200 mg
Pb/kg). These heavy metals can affect plant growth and have a negative im-
pact on the nutritional value of the crops. Cabbage [Brassica oleracea (Capita-
ta Group)] and barley were grown on soil containing from 0 to 40010 (wt./wt.)
of the incinerator fly ash. Plant growth was reduced by the fly ash, and the
yield of the barley crop in the 40010 amendment group was only about 30%
of the control value. The first crop of cabbage and barley contained 0.51
and 1.08 mg Se/kg, respectively, when grown in media containing 20010 ash
(wt./wt.) compared with 0.01 and 0.07 mg Se/kg when grown in the control
media not containing ash.
Corn (Zea mays L.) was grown in two successive years on soil amended
with 1 x 106 kg/ha (500 tons/acre) coal-derived fly ash (Combs et al.,
1980). Use of the fly ash resulted in a sevenfold increase in total Se in corn
grain produced during the two seasons after application of the fly ash. The
Se in this corn had a Bioavailability to chicks (Gallus gallus) of about 46010
when compared with that of selenite.
Animals fed plants grown on fly ash or fly ash-amended soils have ab-
sorbed some of the Se as evidenced by increases in tissue Se concentrations
(Furr et al., 1975, 1978; Stoewsand et al., 1978). Yellow sweet clover [Melilo-