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To investigate metal uptake by crops and their effect on soil microbiology (follow on SP0112) - SP0102

Description
SP0102. Heavy metals in sewage sludge.

An EC Directive limiting the maximum concentrations of metals in sludge-treated soils was introduced in 1989 to reflect concern about the environmental risks of metals; however, it has been shown that soil microbes are more sensitive to metals than previously thought and there are adverse effects on these organisms at concentrations below existing legislative limits. This study will aim to identify pathways and fates of heavy metals derived from sewage sludge and their effect on soil, water, crops and grazing animals in order to revize current sludge disposal guidelines. Effects of metal levels below current statutory limits on soil microbial activity and populations will also be studied. Methods for assessing tolerance of Rhizobium isolates to Zn, Cd, Cu and Ni will be developed. Mycorrhizal infection of clover in one sludge-contaminated and one uncontaminated plot will then be measured. Efficiency of formation of microbial biomass carbon and nitrogen in soils from contaminated and uncontaminated plots will be measured. Effects of sludge metals on 4 other legume species will also be determined and chemical analyses of sludges and soils conducted.
Objective
To identify pathways and fates of heavy metals derived from sewage sludge and their effect on soil, water crops and grazing animals so as to update current disposal guidelines by 1994 and to provide interim advice by the end of 1990 and 1992 for national discussions. Secondary objectives: To provide guidance on maximising beneficial uses of sewage sludges as a fertiliser. To determine whether concentrations of metals below current statutory limits for soil affect soil populations and activities of soil microbes by----(Roame incomplete)
Project Documents
• Final Report : To investigate metal uptake by crops and their effect on soil microbiology   (130k)
Time-Scale and Cost
From: 1991

To: 1994

Cost: £397,000
Contractor / Funded Organisations
Rothamsted Research (BBSRC)
Keywords
              
Fields of Study
Soil Protection