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Field study of the effects of liquid digested sewage sludge on agricultural landTaylor, David. January 1981 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 76-82).
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Effect of sewage sludge and clearfelling on the nutrient cycling of a mature Scots pine (Pinus sylvestris L.) standMitchell, Diane January 1996 (has links)
The effects of sewage sludge application and the additional effects of clearfelling on nutrient cycling have been assessed in a mature Scots pine stand, north-east Scotland. The forest site was situated in a low rainfall area with high evapotranspiration and low leaching losses. The ground vegetation formed an important sink for N and P following sludge addition and clearfelling. Sludge application caused a foliar N response, increased foliar needle weight, and litterfall showed a significant and rapid potential to immobilize NH<sub>4</sub>-N and PO<sub>4</sub>-P added in sludge. The soil availability of NH<sub>4</sub>-N and PO<sub>4</sub>-P together with rates of mineralization of N and P and nitrification in sludge-treated areas were significantly increased compared with that of the control. Concentrations of NH<sub>4</sub>-N, NO<sub>3</sub>-N, PO<sub>4</sub>-P and organic P were increased significantly following sludge addition and fluxes were an order of magnitude greater than that of the control. Peaks in concentrations of NH<sub>3</sub>-N in sludge-treated areas exceeded the EC limit of 11.3 mg 1<sup>-1</sup> on several occasions. Of the total N and P applied to the sludge, throughfall and litterfall over a 17 month period, 2.4 % and 0.72 % were measured in the B<sub>s</sub> soil horizon flux. After clearfelling, initial increases in soil availability of NH<sub>4</sub>-N, NO<sub>3</sub>-N andPO<sub>4</sub>-P were measured. Felling increased nitrification rates, although increases were significant only in areas previously treated with sludge. Fluxes of NO<sub>3</sub>-N, NH<sub>4</sub>-N and PO<sub>4</sub>-P and organic P were increased at least an order of magnitude greater in felled areas than those of the control. Immobilization of N and P was greater in green and abscised litters placed in previously sludge-treated areas than compared with those placed in control areas.
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Agricultural recycling of sewage sludge for maize and oats cultivationHenning, Barend Johannes January 2000 (has links)
Please read the abstract in the dissertation. / Dissertation (MSc)--University of Pretoria, 2000. / Plant Science / unrestricted
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