The article deals with the economic evaluation of technical support for the technologies of growing agricultural crops characterised by the indicators of efficiency and cost of technical means. Impact of the amount of work is shown upon the level of technical support using the technological operations of pre-sowing soil preparation and sowing by means of a combined aggregate for cereal cultivation as an example. Estimation is shown for the application of a high level of technical support at the expense of increasing the yields. Economic-mathematical models were applied for the solution of this task which took into account the impact upon saving labour resources (employment of machine operators), environment protection (consumption of fuel), and the economic aspects (lowering the reduced costs). The results obtained during the process of optimisation indicate that each level of technical support for the technologies of growing agricultural crops has an economically expedient limit of its application. It is a corresponding amount of the performed work, the time of its execution connected with the costs, and the degree of the necessary capital investments. Estimation of the enumerated factors presents a possibility to determine the forms of application of the machinery - its acquisition as individual property, for collective use, or its leasing. The presented approach to the evaluation of the level of technical support of technologies allows also obtaining information in order to make a motivated decision when purchasing machine and tractor aggregates, selecting technologies, and shaping the structure of tractor aggregates on the farm.