The article presents the results of field experiments in the period from 2020 to 2022, studying the effect of mineral fertilizers on the biochemistry of oat grain in the Northern Trans-Urals. The research was carried out on leached chernozem in the forest-steppe zone of the Trans-Urals, Tyumen region, the village of Uteshevo. In the experiment, oat varieties were studied: Talisman, Otrada and Thomas, bred at the Tyumen Scientific Center of the SB RAS.By applying mineral fertilizers, the following agrophones were created in the experiment: natural agrophone - without fertilizers; low - N60P20; medium - N90P40; high - N150P60; very high - N200P80. Oat varieties have biological features for the assimilation of nutrients from soil and fertilizers. Biochemical analysis of grain showed that under the influence of fertilizers, the protein content increases from 6,1-7,0 to 8,4-11,8%. Minimal responsiveness to fertilizers was manifested in the Talisman cultivar, where the protein content reached 10,6% only in a dry year. The fat content in the grain directly depends only on the variety of oats, and the starch content in the grain of oats is determined by weather conditions.