## 2 Materials and Methods  
### Site Description and Experimental Design  
Experimental field research was carried out at the Experimental Station of Vytautas Magnus University Agriculture Academy (54\({}^{\circ}\)534\({}^{\prime}\)N; 23\({}^{\circ}\)50\({}^{\prime}\)E), Kaunas district, Lithuania,in 2016 and in 2017. The field site was located the southwest side of Kaunas city, on the left side of the Nemunas river. It is characterized by a slightly wavy plain, and the soil that has formed in the area represents bottom moraine or bottom glacial deposits that are covered with limnoglacial sediments and deeply lukewarm soaked soil (Endohypogleyic-Eutric Planosol--PLe-gln-w). The average soil pH was 6.5-7.2, total nitrogen 1.47-1.59%, humus 2.2-3.0%, mobile phosphorus 173-235 mg kg\({}^{-1}\), mobile potassium 115-189 mg kg\({}^{-1}\), and mobile sulfur 5.6-26.4 mg kg\({}^{-1}\). The research was carried out under meteorological conditions of central Lithuania: the annual amount of precipitation was 844 mm in 2016. Precipitation was particularly high in July (162.9 mm) and August (114.9 mm), when shallow tillage was carried out after the harvest. In 2017, the annual precipitation was 522 mm (79.6 mm in July, 55.0 mm in August). The average temperature in 2016 was 7.7 \({}^{\circ}\)C (17.9 \({}^{\circ}\)C in July, 16.9 \({}^{\circ}\)C in August), and in 2017--8.7 \({}^{\circ}\)C (16.8 \({}^{\circ}\)C in July, 17.5 \({}^{\circ}\)C in August).  
The area of the experimental field studies of 19200 m\({}^{2}\) was divided into 8 experimental treatments, each of which had an area of 2400 m\({}^{2}\) (length of 200 m and width of 12 m) (Figure 1). There were 4 replicates in each treatment.  
In spring, after the resumption of plant vegetation, winter wheat \"Famulus\" in 2016 and winter oilseed rape \"Cult\" in 2017 were sprayed with 4 different biopreparations and their mixtures using \"Amazone\" sprayer (model UF-901) manufactured in Austria company \"Josef Duben KG\" (Sitzendorf an der Schmida, Austria). The rate ranged from 1.0 to 4.01 ha\({}^{-1}\). Biopreparations were mixed with water at 200 l ha\({}^{-1}\). The composition of the biological preparations are provided in Table 1.  
Figure 2 shows the plan of experimental research, indicating the technological operations of plant cultivation, the place of spraying of biological preparations in the sequence of these operations, the place of determination of plant residues, soil properties, and traction forces of till  
\begin{table}
\begin{tabular}{c c} \hline \hline
**No.** & **The Composition of the Biopreparates** \\ \hline
1 & Essential oils of plants; 40 species of various herb extracts; marine algae extracts; mineral oils. \\ \hline
2 & _Azospirillum_ sp. (N), bacterial colony count—1 \(\times\) 109/mL; _Frateuria aurentia_ (K), bacterial colony count—1 \(\times\) 109/mL; _Bacillus megaterium_ (P), bacterial colony count—1 \(\times\) 109/mL; seaweed extract—10% by volume. \\ \hline
3 & _Azobacter chrooccecum_, 1 \(\times\) 109/mL—non-membrane, nitrogen-fixing bacteria; _Azospirillum brasilense_, 1 \(\times\) 109/mL—non-membrane, nitrogen-fixing bacteria; Phosphorus P (P\({}_{2}\)O5)—7.5%; Potassium K (K\({}_{2}\)O)—7.5%; seaweed extract—10% by volume. \\ \hline
4 & _Azobacter vinelandii_ 1 \(\times\) 109 mL; 5% of solids; 4.5% of humic acids; 0.5% gibberellic acid; 0.01% copper (Cu); 0.01% zinc (Zn); 0.01% manganese (Mn); 0.01% iron (Fe); 0.01% calcium (Ca); 0.005% sodium molybdate (Na\({}_{2}\)Mo0\({}_{4}\)). \\ \hline \hline \end{tabular}
\end{table}
Table 1: Compositions of biopreparates.  
Figure 1: Experimental design of field research: 1, 2, 3, 4—repetitions; 5—accounting field; 6—protection zone.  
Prior to tillage, soil density and porosity were sampled using a soil drill. For each treatment, 5 soil samples were taken from each soil layer at a depth of 0-250 mm in each replicate. Experimental sampling was random on both sides of the tramlines. Soil properties studies were performed in 5 replicates. Total soil porosity was determined using an Air Pycnometer.