Abstract
Soil β-glucosidase participates in the final step of cellulose biodegradation. It is significant in the soil C cycle and is used as an indicator of the biological fertility of soil. However, the response of its kinetic parameters to environmental temperature and moisture regimes is not well understood. This study tested the β-glucosidase response in the main agricultural soils (black soil, albic soil, brown soil, and cinnamon soil) of Northeast China. Incubation tests were conducted to measure the kinetic parameters Km, Vmax or Vmax/Km of soil β-glucosidase at environmental temperatures of 10, 20 and 30 ºC and at 10, 20 and 30 % soil moisture content. The insensitive response of the kinetic parameters to temperature changes indicates that soil β-glucosidase was present primarily in immobilized form. The significant response of the kinetic parameters of soil β-glucosidase to soil moisture rather than to environmental temperatures suggests that the catalytic ability of soil β-glucosidase was sensitive to changing soil moisture regimes.
Highlights
Parts of the subsamples (1,000 g; n = 3) of each composite sample were preincubated at ca. 60 % water-holding capacity (WHC) and 25 °C for 14 days to stabilize the biological and biochemical characteristics of the soil before the experiment
Some studies showed that soil enzyme activity was strongly affected by the soil moisture regime (Skujins & McLaren, 1969; Kramer & Green, 2000; Yavitt et al, 2004)
Temperature and moisture affected the kinetic parameters of soil β-glucosidase
Summary
Four sampling sites were selected from black, albic, brown and cinnamon soil sites in Northeast China as described by Zhang et al (2009). 60 soil samples (0 - 20 cm) over approximately 1 ha at each site were collected in early spring before sowing. Three plots of 50 × 80 m at each site were selected for soil sampling. The 20 samples from each sampling plot were mixed to form a composite sample, transported to the laboratory in isothermal bags, and passed through a 2.0 mm sieve. Some sieved samples were air-dried for analysis of chemical and physical properties. Physical and chemical properties of the studied soils are given by Zhang et al (2009). Distilled water was added daily to compensate for the water loss from incubation
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