FIELD TESTS OF THE UNIT FOR ANHYDROUS AMMONIA APPLICATION INTO THE SOIL
The studies were carried out to determine the compliance of traction and speed indicators of the tractor as part of the machine-tractor unit to the requirements of aggregation, taking into account the random nature of changes in external operational factors. The unit Fendt 936 Vario + AVA-12.6 “Agropitatel” was used; the tests were run in the Leninsk-Kuznetsk District of the Kemerovo Region in 2017. The probabilistic characteristics of the traction resistance of the agricultural machine, its dependence on the speed of movement on the operations of the main tillage and intra-soil application of liquid fertilizers were determined by the method of control dynamometry. The studies were carried out on medium humus podzolized chernozems on stubble at a depth of 16 and 21 cm and an average run length of 1030 m. The given (to 5 km h) values of the specific traction resistance of the unit in the operations of tillage and fertilization were 2.99 and 5.04 kN m, respectively, the proportionality coefficient - 0.057 s<sup>2</sup> m<sup>2</sup> and 0.034 s<sup>2</sup> m<sup>2</sup>, variations - 10.5 and 2.1% (p < 0.05). With increased depth of the working bodies of agricultural machinery by 5 cm, there is an increase of the specific traction resistance of the unit by 68.6% while reducing the variation of the indicator - by 5 times. Also the difference between the indices traction-speed significantly reduced - 1.7 times. The tractor Fendt 936 Vario does not meet the requirements for the working speed and slipping of the drive wheels when working within the range of average specific traction resistance obtained under test conditions; that requires the development of guidelines for rational aggregation of agricultural machines.