Biochar (BC) is a material that finds many applications in agriculture and environmental activities. The aim of the study was to define the influence of biochar produced from various organic materials: mellow compost (MC), stabilized municipal sewage sludge (MSS), pine sawdust (PS), sycamore sawdust (SS) and oak leaves (OL) on soil enzyme activity, as well as its relations with carbon and nitrogen content. After a 60-day incubation of soil and BC, the activity of dehydrogenases (DEH), catalase (CAT), alkaline (AlP) and acid (AcP) phosphatases was investigated. The basic parameters of soil were also determined: TOC, TN, DOM, pH in H₂O, available phosphorus (AP). The highest AP content was obtained in the S + MSS, S + OL and S + MC variants. Enzyme activity was highest in soil with MSS BC, regardless of incubation time. After 60 days, the activity of soil enzymes was inhibited. The obtained results indicate that the response of enzymatic activity to biochar depends on the feedstock material and the incubation time. When using BC as an exogenous matter, it is necessary to determine the TOC/TN ratio. For the very wide range of this parameter, supplemental nitrogen fertilization or mixtures of different biochars should be applied.

The chemical properties and enzymatic activity of the surface soil horizon were compared between an organic farm (OF) (crop rotation with legume plants, fertilisation with manure) and a conventional farm (CF) (simplified crop rotation, mineral fertilisation, chemical crop protection products). In the years 2001-2017 on the OF (near the village of Juchowo, northern Poland), a reduced tillage system (ploughless) was used, while plough cultivation was used on a CF located in its immediate vicinity. The parameters used to assess the properties of soils were: particle size composition, pH, total organic carbon (TOC) and total nitrogen (TN), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). The activity of dehydrogenases (DEH), catalase (CAT), alkaline phosphatase (AlP) and acid phosphatase (AcP) and the content of easily extractable glomalin-related soil protein (EEGRSP) were also determined. Sixteen years of soil use in accordance with ecological principles significantly increased the average content of TOC, NT, DOC and DON. Soil samples rich in TOC and DOC showed significantly higher DEH and AcP activity, and EEGRSP content. Statistical analysis showed that the activity of DEH, AlP and CAT in the soil was significantly higher for the OF than for the conventional cultivation system. Limiting soil cultivation procedures on the OF improved the balance of soil organic matter (SOM) and pH value, and significantly increased the content of EEGRSP as compared to the cultivation system used on the CF.

This paper summarizes research work on the seasonal and profile dynamics of phosphorus content and the activity of phosphatase in soil next to the nitrogen industry. The results are presented of the total phosphorus (TP) and available phosphorus (AP) content and the alkaline phosphatase (AlP) and acid phosphatase (AcP) against the basic physicochemical properties (clay, pH, total organic carbon, total nitrogen). Three soil profiles were sampled from Brunic Arenosols 0.8, 2.0, and 2.5 km away from the nitrogen plant. The control profile was taken from the Tuchola Forest. The soil was collected in both spring and autumn. The results showed that the total phosphorus content was higher in spring than in autumn (the value of index of changes in time TI < 0) contrary to available phosphorus (TI > 0) and in both seasons in surface soils, the lowest, in profile I. Both total and available phosphorus decreased with depth along the soil profiles. The distribution index (DI) calculated for total phosphorus in surface soils demonstrated a rather moderate accumulation, while DI value for available phosphorus for profile III, a considerable accumulation. The availability factor (AF) for all the soil samples was above the threshold of phosphorus load (2%) in the two seasons in this study (from 2.00 to 10.13% for spring and from 3.92 to 21.19% for autumn), suggesting that the transformation rate from TP to AP was high, and AP supply for plant growth was sufficient. The correlation analysis showed a significant and positive correlation of available phosphorus with soil properties such as total organic carbon (r = 0.577), total nitrogen (r = 0.512), and clay (r = 0.493); however, there was no correlation with the activity of phosphatases.

The aim of the research was to evaluate the influence of car traffic on the content of selected heavy metals in soil from a park area, and to define the dependency between their content and enzyme activity. Soil samples were collected from 13 points located along a communication route, each 100 m from the next and 50 m from the border of the road. Soil material was obtained from two depths (0–20 cm and 20–40 cm) and analysed for: pH in H₂O and in KCl, OC, and texture by laser method. Total content of heavy metals (Pb, Cd, Zn, Cu, Ni), available phosphorus and the activity of selected enzymes: catalase, dehydrogenase, acidic and alkaline phosphatase were all determined. The examined soils have the texture of loamy sands or sands (USDA 2012), slightly acidic or neutral pH, Organic Carbon (OC) content in the range from 3.50 to 13.80 g kg⁻¹. The total contents of elements in surface horizons were, in order of decreasing concentrations: Pb>Zn>Cu>Ni>Cd, although in subsurface horizons it was Zn>Pb>Cu>Ni>Cd. Contamination Factor (CF) determined for Ni, Pb, Cd, Zn, Cu reaches higher values in samples from subsurface horizons, which confirms the influence of car traffic on the content of heavy metals in the surrounding soils. The calculated CF shows contamination is moderate for Ni, Cd, Zn and Cu and high for Pb and Cu. The investigated soils may be classified as class IV (low) in terms of available phosphorus. The activity of the examined enzymes was higher in soil samples collected from the 0–20 cm layer than from 20–40 cm. The correlation analysis indicates a significant positive dependency between OC content in soils and enzymatic activity. Principal Component Analysis (PCA) was also performed. Two principal components PC1 and PC2 account for 66.57% of the variability.

The activity of enzymes in soil is sensitive to the changes in soil properties affected by biotic and abiotic factors. This study investigates the influence of salinity on some enzymes (catalase CAT, dehydrogenases DEH, alkaline AlP, and acid AcP phosphatase) and pH in 0.01 M CaCl₂, EC_e, the content of total organic carbon, and total nitrogen in technogenic salinization soil next to the soda plant. Seven soil sampling sites were selected (S1–S6) in the area close to the soda plant and C (the control). Based on the enzyme activity, also soil indicators were calculated: the resistance index (RS), enzymatic pH indicator \( \frac{\mathrm{AlP}}{\mathrm{AcP}} \), the factor of the impact of anthropopressure (IF), the biological index of fertility (BIF), and the indices of biochemical soil activity (BA12 and BA13). The above study did not show one-way changes of the parameters investigated. The relations between the parameters and the activity of catalase, dehydrogenase, alkaline, and acid phosphatase show that they are mostly determined by the state of salinity of the soil environment. The calculated index of resistance (RS), as an effective means of the enzymatic response to environmental stress, facilitated putting the enzymes in the following series: CAT>DEH>AlP>AcP. It shows that catalase and dehydrogenases are most resistant to the anthropogenic factor. The calculated values of BA12 and BA13 indices showed the differences between technogenic salinization soils and the soil sampled from the control. The lowest BIF values were observed at S6 and S3, S4, and C.