No abstract

The mechanization technologies of soil works have a major impact on physical state of soil. This situation is generated by the mechanical action of working parts which are involved in soil works and by the traffic of running systems of tractors and agricultural machines. These mechanization technologies have been tested to determine which of them correspond to the highest degree of sustainable agriculture concept and ensure protection, preservation and improvement of agricultural lands. The testing results of mechanization technologies for soil works variants which include a wide spectrum of conservative and unconventional works, performed with appropriate equipment, were compared both between them and also with witness variant which involved the classical and conventional technologies for soil processing. In the variants of selected mechanization technologies, the soil works are reduced even up to their total disappearance. This is the situation of directly sowing into the stubble, in unploughed or untillage soil.

The paper establishes the value of the average pressure at the contact surface level between the soil and the tires of the following vehicles and trailers: the U-650 and Valtra T-190 tractors, the 2RB5AT and 7RBAT trailers and the large dump capability Iveco Trakker 8x4. The wheelground pressure is determined as the report between wheel corresponding weight and the contact surface area with soil. This area was obtained by calculation, using 12 types of equations established by different authors. In this paper, we used the average of the 12 versions, both for the wheel-soil surface and for the wheel-ground pressure. It was found that the lowest wheel-ground pressures are recorded for the Valtra U-650 and T-190 tractors (63,535 ... 142,821 kPa) and the highest in the case of the 7RBAT and 2RB5AT trailers and the Iveco Trakker 8x4 dump (432,692. .. 623,414 kPa), the maximum imposed limit by agricultural requirements being 100 kPa. Regarding the tractors, the exceeding of the imposed limit (100 kPa) is recorded for all the wheels of the Valtra T-190 tractor and only for the front wheels of the U-650 tractor. These excesses are quite small (10 ... 42 kPa), so practically will not affect soil properties. For the trailers and dump, the wheel-ground pressure is 4,3 ... 6,2 times higher the upper limit imposed for agricultural soil, 100 kPa. These high pressures don't affect the asphalt or concrete roads, but will adversely alter the physical properties of agricultural soils.