Enzyme activities were done on fresh, moist, sieved (b2 mm) soils.
Control tests with autoclaved soils were included in all enzymes assays
to evaluate the spontaneous or the abiotic transformation of substrates.
The sameprocedureas for theenzymeassaywas followed for the controls
but the substrate was added to the soil after incubation and immediately
prior to stopping the reaction. All determinations weremade in triplicate
and the results were corrected for oven-dry (105 °C) moisture content.
The activity of dehydrogenases was given in cm3 H2 necessary to reduce
TTC to TFP (triphenyl phormosan); of phosphatases – in mmols of
p-nitrophenol (PNP) produced from sodium 4-nitrophenylphosphate;
urease – in mg N-NH4
+ formed from hydrolysed urea; protease – in mg
tyrosine developed from sodium caseinate. Additionally, the basic chemical
properties of the investigated soils were indicated: pH in H2O and in
1 mol·dm−3 KCl (ISO 10390) and organic carbon (ISO 14255), ammonia
nitrogen and nitrate nitrogen (ISO 14255).