Maintaining soil fertility is one of the main objectives of agricultural production. An important factor in soil fertility is its optimal structure. For the minimum cultivation of soil widely used equipped with spherical cut-off discs heavy harrows. The purpose of their use, along with others, in the cultivation of heavy soils, for example, chernozems, is the depression of soil boulders and, thus, the optimal structure. In the conditions of intensification of agricultural production under the influence of such soil-working tools in the cultivation of malocontuitive sod-podzolic soils and running gears of mobile equipment, the destruction of the soil structure, the reduction of the number of agronomically valuable water-supply units, and the spread of soil. Thus, for the cultivation of such soils, it is necessary to use discs of another profile, which would ensure the minimum destruction of agronomically valuable watertight aggregates. In order to create such a working body, the process of structuring the agronomically valuable water-conserving aggregates, factors influencing it and analyzing the energy criteria for the formation of a water-tight structure is considered. The features, which arise during mechanical cultivation of soil, influence of cultivation on its structure and features of the stress-strain state of soil are studied. A mathematical model is developed that allows calculating the stress state of the soil and designing the most rational form of disk working bodies. In the conducted studies, the influence of the depth of cultivation, the number of cutouts, the size of the cutout angle and the length of the chord of the projection were studied. On the basis of the developed mathematical model, a rational profile of the disk working organ for the cultivation of small-coupling sod-podzolic soils was obtained and its tests were performed, which showed a decrease of the erosion-dangerous particles of the soil by (<0,25 mm)  24%.

Relevant resources for renewable biomass fuel production are wood, cereal straw residues, and emergent vegetation from wetlands. Peat is an important slowly renewable biomass fuel too. Using blended peat and woody or herbaceous biomass, sulphur content of the fuels is increased and, if the mixture is burned, sulphates are formed instead of chlorides, and the risk of high temperature corrosion is avoided. The loading, storage container discharging, mixing and automatic feeding process depends on internal stresses acting in the biomass volume. To estimate vertical stress in silos, a mathematical model was built. Vertical stress in the opening of the silo hopper reaches 1.4 kPa if the diameter of a silo is 0.4 m, but for the diameter of 2 m it is possible to obtain even 7.2 kPa. Increase of the coefficients lambda and mu to the maximal values (lambda = 0.6; mu = 0.5) decreases vertical stress for more than 70%.