A field experiment with spring barley was conducted in 2007-2009 at the Experimental Farm Czesławice (central part of Lublin region) on lessive soil developed from loess (2nd bonitation class). The research included 3 doses of herbicides, fungicides and a retardant (100%, 75%, 50%) as well as the type of adjuvant applied (superficially active, oil, mineral). Control objects without adjuvant were also taken into consideration. The object of the experiment was the content of nutrient in the grain (protein, fat, fibre, ash extract, N-free extract), protein yield and correlation between chosen elements of the grain and the occurrence of agrophages. It was proved that the reduction of pesticide doses by 50% caused a considerable decrease of the protein, fat and fibre in spring barley grain as compared with the 75% dose and with the maximum dose. Thanks to the addition of adjuvants (especially oil adjuvant) to the spraying liquid the reduction of pesticides doses by 25% did not cause deterioration of grain quality. Further reduction (by 50%) of pesticide doses, in spite of interaction with adjuvants, had a negative effect on the content of the analysed nutrients in the grain. The above situation resulted from increased proportion of agrophages in barley canopy (especially air-dry weight of weeds and fungal diseases of culm base). Among the tested adjuvants, irrespective of the pesticide doses, the oil adjuvant Atpolan 80 EC had the greatest effect on the modification of beneficial nutrient composition of barley grain.