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Sewage sludge as a fertilizer of pole stage forests: short-term hydrochemical fluxes and foliar response

Ferrier, R.C., Edwards, A.C., Dutch, J., Wolstenholme, R., Mitchell, D.S.
Soil use and management 1996 v.12 no.1 pp. 1-7
Pinus sylvestris, forest soils, sewage sludge, land application, organic fertilizers, nitrogen fertilizers, phosphorus fertilizers, leaves, conifer needles, nutrient content, soil, phosphorus, potassium, calcium, nitrogen, nitrate nitrogen, ammonium nitrogen, sulfur, magnesium, zinc, copper, leaching, throughfall, water pollution, eutrophication, chemical constituents of plants, biogeochemical cycles, soil horizons, risk, Scotland
Proposed restrictions on the disposal of sewage to the marine environment means that alternative land based outlets are required in the UK. Commercial forestry represents a significant land use that could receive and benefit from the application of sewage sludge, to overcome the generally poor soil nutrient status. The oligotrophic and sensitive nature of surface waters in many afforested areas requires that the environmental consequences of the widespread use of organic fertilizers in forestry are carefully considered. This paper compares the effects of an N and P fertilizer with that of sewage sludge on the nutrient content of foliage in a pole stage Scots pine (Pinus sylvestris) forest and of nutrient fluxes in soil. Both conventional fertilizer and sewage treatments had significant but differing effects on the availability and leaching of the major nutrients, especially N and P. Evidence for increased nitrification and nitrate production with time was apparent for both treatments. Fluxes of N and P in mineral horizon leachate were consistently smaller than those from the overlying organic horizon. Foliar nutrient concentrations after one year were significantly higher (P < 0.01) in all of the treatments, and conventional fertilization with urea produced a significantly higher foliar N concentration than that measured in the sludge-treated plots. There was no evidence for appreciable N or P leaching from the site within a year of sludge application.