The aim of the study is the assessment of the management effectiveness of production resources on farms of various sizes focused on cultivating cereal, oil and protein crops against a background of total field-crop farms and total farms. The assessment covered farms encompassed by the FADN system in 2017 in the scope of production organization and intensity, production and economic results as well as the effective management of resources. The productivity and profitability of resources on cereal farms was found to be on a far lower level, however, as farm size increased, the productivity of land resources generally rose, too. There is a reverse tendency when compared to the tendencies observed in the total number of farms, including horticulture farms. Together with an increase in farm size, differences in profitability declined. The greatest differences were observed when it came to land resource profitability, while the least in the scope of labour profitability. Therefore, it can be assumed that by increasing the size of cereal farms, the effectiveness of managing land resources on such agricultural holdings will clearly improve.