Chapter E: Selenium mobility in soils and its absorption, translocation, and metabolism in plants

Mayland, H.F. and Gough, L.P. and Stewart, K.C. (1991) Chapter E: Selenium mobility in soils and its absorption, translocation, and metabolism in plants. pp. 55-64. In: Severson, R.C. and Fisher Jr, S.E. and Gough, L.P. (eds.) Proc. of 1990 Billings Land Reclamation Symposium. USA-MT-Billings, 1991/03/25-30.

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Abstract

Forms of selenium found in soils influence its mobility,
uptake, and metabolism by plants. The major forms in alkaline,
oxidizing environments which are available for plant uptake
are selenium-VI as selenate, Se04 2-) and selenium-IV (as
selenite, SeO3 2-). The major influences on uptake are soil pH
and salinity. High salinity and pH favor selenium anion
adsorption onto clays and metal oxides. Selenite is adsorbed
much more strongly than selenate leaving selenate as the
major form available for plant uptake. Some soil anions, such
as phosphate, increase plant selenium uptake because
increased soil-solution anion concentrations compete with
selenium anions for adsorption sites. Other anions, such as
chloride or sulfate, actually enhance or inhibit uptake by
affecting plant metabolism.
Inorganic selenides and elemental selenium are mostly
insoluble except under conditions of low pH in moist,
reducing environments. In these conditions organic selenides
may also be found as selenium amino acids, such as selenoglutathione,
and in various fractions of humic substances.
Although it is unclear whether organic selenides are absorbed
from soil by plants, they have been identified in soil solutions
as products of bacterial and plant metabolism. Volatilization of
organic selenium compounds makes mass balance studies of
selenium difficult.
Selenate ions are rapidly absorbed and transported in
plant xylem sap. Selenite absorption, on the other hand, is
slower, but the selenium is more rapidly metabolized to
organoselenium compounds and transported into upper
portions of the plant.
Soil and plant management in seleniferous areas must
take into account soil types and the genetic tolerance by plants
of high selenium and salt concentrations. For example, plants
will tolerate more selenium on high-sulfate soils than on low
sulfate soils. Some plants, such as alfalfa, are very sensitive and
will show signs of damage at low soil selenium concentrations
while others, such as saltbush, may accumulate thousands of
milligrams per kilogram of selenium without damage. Some
arid and semiarid soils may need to be managed by prudent
irrigation practices in order to reduce selenium and salinity to
acceptable levels.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	0744
Additional Information:	**A.K.A NWISRL PUBLICATION 744a**
Subjects:	Soil > Chemistry > Selenium Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:56
Last Modified:	08 Dec 2016 18:56
Item ID:	909
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/909