Tarrasón D, Ojeda G, Ortiz O, Alcañiz J M
CREAF (Centre for Ecological Research and Forestry Applications) and Ecology Unit, Department of Animal Plant Biology and Ecology, Autonomous University of Barcelona, E-08193, Bellaterra, Spain.
Bioresour Technol. 2008 Jan;99(2):252-9. doi: 10.1016/j.biortech.2006.12.023. Epub 2007 Feb 22.
Anaerobically-digested sludge called fresh sludge (F), composted sludge (C) and thermally-drying sludge (T), all from the same batch, were applied to the surface of a calcareous Udic Calciustept with loamy texture. Dosage equivalent was 10 t ha(-1) of dry matter. The concentration of mineral nitrogen (ammonium and nitrate) in the soil was measured in order to estimate the effects of the post-treatments to which the different kinds of sewage sludge are subjected in relation to the availability of N in the surface layer of the soil. The most significant differences in NH(4)-N and NO(3)-N concentrations due to the transformation of the organic matter were observed during the first three weeks following soil amendment. Thermally-dried and composted sludge initially displayed higher concentrations of ammonium and nitrate in soil. Five months after the amendment, soil applied with fresh sludge showed the highest concentrations of NH(4)-N and NO(3)-N (6.1 and 36.6 mg kg(-1), respectively). It is clear that the processes of composting and thermal-drying influence the bioavailability of nitrogen from the different types of sewage sludge.
