The effect on copper content of herbage and accumulation of copper in soil following application to agricultural land of pig slurry containing up to 760 mg Cu/kg D.M. was investigated in field experiments. The slurry was produced by pigs receiving supplementary copper at a level of 200 mg Cu/kg in the ration. Incorporation of up to 9 kg slurry Cu/ha into soil increased the copper content of ryegrass/clover sown by a maximum of 1.3 mg Cu/kg D.M. A similar quantity of Cu later applied to the established sward increased the copper content of clover to a maximum of 24.8 and that of grass to 13.4 mg Ca,/kg D.M. Repeated applications of slurry to the soil surface in an established ryegrass sward increased herbage copper from 4 to a minimum of 16 mg kg D.M. on a sandy soil and from 8 to a maximum of 23 mgfkg D.M. on an imperfectly draining clay-loam soil. Dilution of slurry with water resulted in greater increases in herbage copper concentration than did undiluted slurry. The addition of 22.3 kg Cu,/ha to a sandy soil of 28.4 kg CuAa to a olayloam soil over a 2 year period increased A-extractable Copper from 2.7 to 19.3 mg Cu/kg on the former soil and from 11.9 to 30.3 mg Cu/kg soil on the latter soil; 89 and 88% of the quantities of slurry copper applied were extractable from topsoil using EDTA. Less than 5 mg WA were found in the aqueous phase in copper-rich slurry, while a fine particulate and colloidal fraction in the solids contained in excess of 2000 mg Cu/kg D.M. Dissolved copper in the aqueous phase when added to soil increased plant uptake of this element. Carbon mineralisation in soil, assessed, by oxygen uptake, was unaffected by addition to soil of a fraction of slurry solids containing 2 g Cu/kg D.M.4. The true availability (4.396) to sheep of copper in slurry was found to be similar to that (3.8%) of copper fed as CuSO4. The availability (5.896) to sheep of Ca in herbage grown on slurry treated land was greater than that (4.8%) in herbage from untreated land. The potential hazards to crops and livestock of disposal of high-copper pig slurries on agricultural land are discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:660755 |
| Date | January 1979 |
| Creators | Price, J. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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