Sludge - a resource whose time has come
Sewage composition, median figures based on samples collected from 200 different sources in eight states, consists of organic carbon, 30%; total nitrogen, 3.3; total phosphorus, 2.3; total sulfur, 1.1; calcium, 3.9; iron, 1.1; aluminum, 0.4; sodium, 0.2; potassium, 0.3; and magnesium 0.4. In ten years of experiments, Dowdy and his ARS and University of Minnesota colleagues found sludge supplied all the nitrogen and phosphorus that crops could use, but additional potassium was needed. They successfully grew corn, potatoes, green beans, and other vegetables, as well as turfgrasses. The contents of sludge if applied at the rate plants normally use nutrients, are either beneficial or harmless to plants. Public concern is with trace metals, Pb, Hg, Cd, M, Zn, and Cu. Lead and Hg normally in sewage sludge are not available for plant uptake. Zinc, nickel, and copper are not a problem in animal or human food, because plants will stop growing before they can accumulate enough metal to be harmful to animals or people consuming them. Cadmium is taken up by plants, under acid soil conditions. To evaluate the effects of high cadmium feed on livestock, the researchers compared corn silage treated with commercial fertilizer and silage grown on land receiving annual application as high as 20 tons of high Cd sludge an acre. The highest rate of sludge application produced silage containing 5.26 ppM of Cd. This was fed to lambs and dairy goats. Cadmium concentration in goat's milk, did not increase as result of eating the silage. However, cadmium concentration did increase in the kidney and liver tissue of both goats and lambs. Soil acidity is the major soil characteristic that affects trace metal uptake by growing plants. Where soil acidity is maintained at a pH value of about 6.5, only a small percentage of sludge-borne metals will be absorbed by a given crop and they will not leach into groundwater.
- Research Organization:
- Univ. of Minnesota
- OSTI ID:
- 5749669
- Journal Information:
- Agric. Res.; (United States), Journal Name: Agric. Res.; (United States); ISSN AGREA
- Country of Publication:
- United States
- Language:
- English
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Cadmium and zinc uptake by corn (Zea mays L. ) with repeated applications of sewage sludge
Cadmium and zinc availability to corn following termination of sewage sludge applications
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALI METALS
ALKALINE EARTH METALS
ALUMINIUM
ANIMALS
BEANS
BIOLOGICAL ACCUMULATION
BIOLOGICAL EFFECTS
CADMIUM
CALCIUM
CARBON
CEREALS
CHEMICAL COMPOSITION
COPPER
DOMESTIC ANIMALS
ELEMENTS
FOOD
GOATS
GRASS
GROUND DISPOSAL
GROWTH
IRON
LAND POLLUTION
LEAD
MAGNESIUM
MAIZE
MAMMALS
MANAGEMENT
MERCURY
METALS
NICKEL
NITROGEN
NONMETALS
PH VALUE
PHOSPHORUS
PLANT GROWTH
PLANTS
POLLUTION
POTASSIUM
POTATOES
RUMINANTS
SEWAGE
SEWAGE SLUDGE
SHEEP
SLUDGES
SODIUM
SOILS
SULFUR
TOXICITY
TRANSITION ELEMENTS
TUBERS
VEGETABLES
VERTEBRATES
WASTE DISPOSAL
WASTE MANAGEMENT
WASTE PRODUCT UTILIZATION
WASTES
ZINC