Results of static field experiment with oats Dragon cv. provided source material for the present paper. Oats were cultivated in 1995-1997 at experimental farm in Mydlniki near Cracow in crop rotation link including fodder maize, spring barley and oats. In statistical calculations the years were considered a first examined factor, while a differentiated soil tillage, i.e. traditional tillage and modified cultivation using deep soil loosening to loosen the under topsoil layer to a depth of 45 cm were considered the second factor. Weather conditions over the experimental period were highly diversified and affected in oats yields. Excessive precipitation, in comparison to oats optimal demand, caused a considerable decrease in grain yield. A beneficial effect of deep loosening did not manifest itself with excessive precipitation.