*3.3. Enzymatic Activity of Soil*

Apart from the numbers and diversity of microorganisms, the biological activity of soil and, thus, its fertility, is determined by the activity of soil enzymes (Table 4). In the present study, the enzymatic activity of soil was significantly affected by the plant crop and its cultivation regimes. The highest activities of dehydrogenases and acid phosphatase were determined in the soil from field pea cultivation, and those of catalase, urease, alkaline phosphatase, β-glucosidase, and arylsulfatase in the soil from winter wheat cultivation. Especially big differences between plant species were noticeable in the activities of alkaline phosphatase and arylsulfatase, which, in the soil sown with winter wheat, were respectively 6.2 times and 2.7 times higher than in the soil from winter rape cultivation, and 3.5 times and 1.9 times higher than in the soil from field pea cultivation. This activity was strongly correlated with the productivity of individual plant species (Figure 8). Considering the total activity of all analyzed enzymes taking part in carbon, nitrogen, phosphorus, and sulfur metabolism, the highest biochemical activity was demonstrated for the rhizosphere of winter wheat, followed by that of field pea and winter rape.

The activities of catalase, urease, alkaline phosphatase, β-glucosidase, and arylsulfatase were positively significantly correlated with the sum of exchangeable base cations and with the degree of soil saturation with base cations (Figure 9). The sorption properties of soil had no effect on the activities of dehydrogenases and acid phosphatase. A similar response of the enzymes was observed regarding the contents of available and exchangeable phosphorus in the soil. The activities of dehydrogenases, urease, phosphatases (both, acid and alkaline), and arylsulfatase were also positively significantly correlated with total nitrogen content of the soil.


**Table 4.** The soil acidity and the cation exchange capacity.

Homogeneous groups denoted with letters (a, b, c) were calculated separately for each enzyme.

**Figure 8.** The yield of plants in kg per m2.

**Figure 9.** Pearson correlation coefficients between enzyme activity and soil physicochemical and chemical properties, *n* = 15, *p* = 0.05, \* significant differences.

#### **4. Discussion**
