عنوان مقاله [English]
The new device made in this study could calculate the proper position of tillage tools relative to the land surface at each point, and hydraulic operator set its optimum position. The optimum position of tools is calculated by depth control software developed for this device, and its input data were depth for root development. The performance of device was tested on subsoiler for precision tillage operation. The accuracy of applying the desired depth was studied in laboratory and also agricultural land. Factors considered in the laboratory were type of depth changing (increasing or decreasing) and seven steps of depth changing in the range of 0 to 350 mm with 50 mm interval. In the field test, in addition to the above mentioned factors, gear changing was also considered (gear 1, 2, 3 of Massey Ferguson Tractor). Precision deficiency for laboratory test was 3.3 percent for increasing and 3.83 percent for decreasing of depth. The precision deficiency in agricultural land was 4.19 percent for gear one, 5.19 percent for gear two and 5.78 percent for gear three. Eventually, this amount for decreasing of depth was 6.84 percent for gear one, 4.67 percent for gear two and 6.14 percent for gear three.