2.6. Determination of soil properties and enzymatic activities
Prior to soil physical and chemical analyses, all samples were air-dried
at room temperature and passed through a 2-mm soil sieve. Soil pH was
measured with combined electrodes in a 1:2.5 soil to water suspension;
available nitrogen was estimated via the alkaline KMNO4method (Prasad, 1965). Soil organic matter was determined as described
previously (Janzen, Bole, Biederbeck, & Slinkard, 1990).
The activities of urease, peroxidase, and phenol oxidase were determined
as described in Saiyacork (Saiyacork, Sinsabaugh, & Zak, 2002).
Catalase activity was measured following the method of Dai et al. (Dai
et al., 2017).