Distribution and Bioavailability of Trace Elements
in Livestock and Poultry Manure By-Products
NANTHI S. BOLAN
Institute of Natural Resources, Massey University, Palmerston North,
New Zealand
DOMY C. ADRIANO
Savannah River Ecology Laboratory, University of Georgia, Aiken, South
Carolina, USA
SANTIAGO MAHlMAIRAJA
Institute of Natural Resources, Massey University, Palmerston North,
New Zealand
" Depending on the degree of intensification of livestock feeding,
animal manures have turned from a precious resource into a waste product."
(Eck and Stewart, 1995)
Intensive confined livestock and poultry production systems generate large
quantities of manure by-products, which have the potential for being recycled
on arable land. Protecting the quality of the environment is a major consideration
when developing management practices to effectively use manure by-products
as a nutrient resource and soil conditioner in agricultural production
system. To date, most of the environmental problems associated with land
application of manure by-products have centered on the contamination of
groundwater and/or surface water with two major nutrients, nitrogen (N)
and phosphorus (P). With increasing use of trace elements (metal is substituted
for trace elements for brevity throughout the text) as nutritional supplement
in the form of feed additive in intensive animal production industries,
manure application has emerged as an important source of certain metals
(e.g., As, Cu, and Zn) input in soils. Unlike application of sewage sludge,
where application rate is limited based on allowable metal loadings, regulations
governing livestock and poultl)l manure by-products are generalyy based
on total N and/or P loading. Both sewage sludge and manure by-products
are applied on land to primarily benefit from their N and/or P content
but without regard to metals in the latter. The danger lies in accumulation
of manure-borne metals since they vertually don't degrade with the potential
of eventually becoming phytotoxic. In order to reduce the risk of offsite
contamination, it is prudent to propose that land application suidelines
for manure by-products be developed that consider their total composition
rather than just only specific compenent (i.e. N amd/or P). The present
review aims to examine the impact of increased usage of certain metals,
especially As, Cu, and Zn, in livestock and poultry production on the
quality of manure by-products. The beneficial effects of these metals
in manure addition to overcome the deficiency of these metals in soils
and the detrimental effects of manure-borne metals on plant growth and
microbial functions are also examined. The practical implications of manure-borne
metals on environmental comtamination are discussed in relation to management
guidelines for the safe and beneficial use of manure by-products in agricultural
soils.
Key
Words: animal manure, bioavailability, biotoxicity, manure, threshold
level
SREL Reprint #2772
Bolan, N., D. Adriano and S. Mahimairaja. 2004. Distribution and bioavailability of trace elements in livestock and poultry manure by-products. Critical Reviews in Environmental Science and Technology 34:291-338.
