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.

Tillage is a significant type of soil intervention and should be conducted based on the specific soil type. The aim of this study was to determine the influence of different tillage intensities (RT: reduced tillage; CT: conventional tillage), which are correlated with carbon sequestration, on soil properties. The study areas included fields on real farms in Eutric Fluvisol (EF), Mollic Fluvisol (MF), Haplic Chernozem (HC), Haplic Luvisol (HL), Eutric Regosol (ER), Eutric Gleysol (EG), and Stagnic Planosol (SP). The effects of tillage systems depended on the soil type and were more evident in soil aggregates of more productive soils. Agronomically, the most valuable fractions of aggregates were dominant in more productive soils (EF, MF, HC) in the CT system and less dominant in less productive soils (HL, ER, EG, SP) in the RT system. Smaller aggregates (<0.5 mm), which indicate deterioration of soil properties, were negatively correlated with clay (r = −0.364, p < 0.01), total organic carbon (r = −0.245, p < 0.05), and stabile carbon fractions (r = −0.250, p < 0.05). In the case of soil organic carbon, tillage system was mainly correlated with soil texture. Tillage had no influence on soils with lower proportions of silt. On the whole, the suitability of the tillage system for a specific soil type depended on soil productivity and soil texture; however, EG was an exception and showed no differences in response to the tillage system used. The results of this study show that the main factors influencing the choice of tillage system are soil type and genesis, soil texture, and soil production ability.

Biochar (BC) is a material that has many applications in agricultural and environmental activities. The aim of the study was to define the influence of BC produced in low-temperature pyrolysis from various organic waste materials, including one-month-old compost (OMOC), pine bark (PB), pine needle mulch (NM), pine cones (PC) and maple leaves (ML), on soil enzyme activity as well as its relation with organic matter properties. A 60-day incubation pot experiment was set up to investigate the influence of BC amendment on soil (S) characteristics. After incubation, we investigated the activity of soil enzymes, the content of available phosphorus (AP), potassium (AK) and magnesium (AMg), total organic carbon (TOC), total nitrogen (TN), dissolved organic matter (DOM) and its fractional composition (content and share of carbon and nitrogen of humic (CHAs, NHAs) and fulvic (CFAs, NFAs) acids and humin fractions). The effect of the amended biochars differed depending on the feedstock material. In general, the use of biochar enriched the soil with AP, AK and AMg increased the soil carbon stock, increased the intensity of nitrogen transformation and influenced the soil enzyme activity. OMOC and ML biochars significantly increased soil fertility, which was expressed by the high value of the CHA/CFA ratio.

The aim of the study was to determine the impact that three cultivation systems—conventional till (CT), reduced till (RT), and strip-till one-pass (ST-OP)—had on the biological parameters of the soil and their relationships with organic matter properties in the row zone (R) and inter-row zone (IR). For this purpose, a long-term static field experiment was carried out, from which soil samples were taken from a depth of 0–20 cm and the following were determined: TOC; TN content and fractional composition of organic matter; activity of dehydrogenases (DEHs), catalase (CAT), alkaline (AlP), and acid phosphatase (AcP); and the abundances of heterotophic bacteria (B), filamentous fungi (F), actinobacteria (Ac), and cellulolytic microorganisms (Ce). Soil samples for biological parameter tests were collected in summer (July) and autumn (October). RT and ST-OP increase the content of TOC, TN, carbon, and nitrogen in the humic and fulvic acid fractions. For the studied groups of microorganisms, the conditions for development were least favourable under CT cultivation. The results show that in July, the activities of DEH and CAT were the highest in ST-OP, whereas in October, they were the highest under CT. AlP and AcP activity were markedly the highest under ST-OP in both months. Enzyme activity was significantly the highest in the IR zone. The results indicate that, of the calculated multiparametric indicators, (AlP/AcP, GMea, BIF, BA12, and TEI), BA12 is a sensitive biological indicator of soil quality.

Research was carried out on the impact of long-term use of cattle manure (30 t ha⁻¹ FYM) and various doses of N (0, 40, 60 and 120 t ha⁻¹) in the form of ammonium nitrate on the following soil parameters: salinity, hydrolytic acidity, total exchangeable base cations, cation exchange capacity, degree of base saturation of the sorption complex, total organic carbon and total nitrogen content, dissolved organic matter, fractional composition of organic matter and content of bioavailable macroelements: phosphorus, potassium and magnesium in the soil of a multi-year static field experiment. The activities of dehydrogenases, catalase, alkaline and acid phosphatase and proteases were also tested. A significant effect of FYM and N fertilisation on the content of bioavailable macroelements was found. The application of manure at a dose of 30 t ha⁻¹ mitigated the negative effects of the application of N at a dose of 120 kg ha⁻¹. A higher content of total organic carbon (8.42 g kg⁻¹) and humic acid fraction (1761 mg kg⁻¹) and higher values of the CHA/CFA ratio (0.79; parameters that are indicators of soil quality) were found in the soil fertilised with manure compared to the soil without manure added (TOC—7.00 g kg⁻¹; CHAs—1285 mg kg⁻¹; CHAs/CFAs 0.66). The activity of the tested enzymes was also significantly determined by the applied fertilisation. Enzyme activity was highest in the soil to which manure had been applied. Nitrogen fertilisation varied in its impact on the activity of enzymes according to the specifics of each enzyme. The content of humic acids and CHA/CFA values correlated positively with the content of soil minerals and the activity of dehydrogenases, catalase, alkaline and acid phosphatase and GMea and TEI indices. Dehydrogenases and acid phosphatase can be considered enzymes that take part in transforming organic matter towards the formation of FAs.

Wheat is the cereal most susceptible to lodging, particularly during the flowering period and at the early ripening stage. The use of plant growth retardants (PGRs) is especially recommended when intensive nitrogen (N) fertilisation is applied, which increases the susceptibility of plants to lodging. This paper presents the results of tests into the effects of PGRs (PGR0—control; PGR1—chlormequat chloride (CCC) + trinexapac-ethyl (TE); PGR2—chlormequat chloride (CCC) + ethephon (ET)), and N dose—N0, N20, N40, and N60 [0, 20, 40, and 60 kg N ha⁻¹] on the content of selected plant secondary metabolites (PSM) in the Indian dwarf wheat (Triticum sphaerococcum Percival) of the Trispa cultivar, and on the abundance of insect pests. In the developmental stage of wheat (BBCH 39), insects were collected with an entomological net. The study also investigated the effect of experimental factors on the physicobiochemical properties of the soil (pH in KC, granulometric composition, total organic carbon TOC, total nitrogen TN, fractional composition of humus, and the activity of enzymes). An increase in the plant secondary metabolite (PSM) and FRAP (ferring reducing ability of plasma) contents following the application of PGRs and N fertilisation already from as low a rate as 20 kg ha⁻¹ was demonstrated. A significant positive correlation was noted between the abundance of Oulema spp. and the contents of total polyphenols, chlorogenic acid, and FRAP. No such relationship was noted for Aphididae or Thysanoptera. TOC content was higher on the plots on which N fertilisation was applied at the highest rate and after the application of PGRs. The factor determining the TN content was N fertilisation. Soil samples of the PGR0 N0 treatment were characterised by the greatest proportion of carbon in the humic and fulvic acid fractions and by the smallest proportion of carbon in the humin fraction. N fertilisation increased the proportion of carbon in the humin fraction on the plots on which no PGRs were applied. The study demonstrated an increase in the activity of oxidoreductive enzymes following the application of higher N rates. The application of PGRs resulted in no inhibition of enzymes in the soil compared to the control (PGRs0).