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Background and objectives Health benefits of whole wheat are partially attributed to phenolic compounds. This study reports the effects of harvest year (Y), nitrogen (N) and sulfur (S) fertilization, and wheat variety (V) on total phenolic content (TPC) and phenolic acid composition of wheat grains. Findings The year effect was significant for TPC and all phenolic acids except for syringic acid. The TPC and phenolic acid composition significantly differed among the varieties, except for vanillic acid concentration. Increased nitrogen fertilizer led to increased production of trans‐ferulic acid, and sulfur application affected the response to nitrogen fertilizer application. Varieties also differed in the response of phenolic acid concentration and composition to sulfur application. Conclusions Year, sulfur fertilization, and wheat variety significantly influenced the total phenolic content and phenolic acid composition of wheat grains. Though nitrogen and sulfur applications had significant effect on wheat phytochemicals, environment (e.g., year), and variety, differences dominated the analysis of variance. Significance and novelty To our knowledge, this is the first study that reports the effects of nitrogen, sulfur, variety, harvest year, and their interactions on phenolic profiles of hard red winter wheat grains. These results will benefit future wheat production practices that aim to produce wheat grains enriched with natural antioxidants.

Winter wheat is often double-cropped after soybeans in no-tillage systems. The soybean crop removes large quantities of sulfur (S), which might cause S deficiency for the following wheat crop. Our objective was to evaluate the responses of three wheat varieties to three nitrogen (N) and four S fertilizer rates representing a range of N:S ratios. The experiment was conducted near Ashland Bottoms and Hutchinson, KS. Treatments were arranged as a complete factorial structure with a split-split-plot design. Variety was the whole-plot, N was the sub-plot, and S was the sub-sub plot. Nitrogen rates were 50, 100, and 150% of the university recommendations for a 60 bushel per acre yield, and S rates were 0, 10, 20, and 40 pounds of S per acre. Wheat varieties evaluated were Zenda, SY Monument, and LCS Mint. Increasing the N rate increased grain yield at both locations. Sulfur increased grain yield at Ashland Bottoms but not at Hutchinson. Nitrogen by S interaction occurred for protein concentration at both locations. At Hutchinson, N rates of 50, 100, and 150% N resulted in grain yield of 62, 73, and 78 bu/a. For the 50% and 100% N rate, protein concentration was 10.8% and 11.3%; however, the 150% N rate with 20 or 40 lb S/a increased protein concentration to 11.8% as compared to 11.5% observed in the 0 or 10 lb S/ a treatments. At Ashland Bottoms, N rates of 50, 100, and 150% resulted in grain yield of 56, 69, and 74 bu/a across S treatments. For the 0 pounds of S per acre treatment, though, these N rates resulted in grain yields of 36, 42, and 40 bu/a. The 150% N rate with 20 and 40 lb S/a increased grain yield by 5 bu/a as compared to the 10 lb S/a treatment. At the 50% N rate, protein concentration was 9.7% with an application of S as compared to 10.3% for the 0 lb S/a, which is due to a dilution effect from the increased grain yield. As S application increased, protein concentration decreased at the 100% N rate. However, at the 150% N rate, protein concentrations were 12.2, 11.5, 11.8, and 11.9% for the 0, 10, 20, and 40 lb S/a, respectively. Our results suggest that a balanced fertilization of N and S are essential for improving yield and protein concentration in no-till systems following soybeans, and that initial S in the profile and soil organic matter (OM) play a crucial role in determining the crop's response to the added fertilizers.