Effects of Foliar- And Soil-Applied Nitrogen and Soil Nitrate-Nitrogen Level on the Protein Content of Neepawa Wheat

Protein content and yield of wheat usually increased with increases in the amount of nitrate nitrogen present in the soil. Large yield increases were obtained when 34 or 67 kg N/ha was applied broadcast to nonfallow land at time of seeding, but protein content decreased or increased only slightly. Protein content increased substantially when 101–202 kg N/ha was applied to nonfallow land, whereas yields were not increased above that obtained with 67 kg N/ha. Protein content of wheat grown on fallow land increased with increasing amounts of added nitrogen up to about 134 kg N/ha; yields did not increase greatly with added nitrogen. Wheat protein content was found to be related to nitrogen supply. An R 2 value of 0.78 was obtained when wheat protein content was related to soil nitrate nitrogen measured to a depth of 61 cm and nitrogen applied broadcast at time of seeding. Soil- and foliar-applied postemergent nitrogen applications increased the protein content more than equivalent rates of nitrogen-applied broadcast at time of seeding in field studies conducted during 1971, but not in 1970. A greenhouse experiment showed that usually less than 1% of the nitrogen from ammonium nitrate, urea, or ammonium sulfate was absorbed into the grain when applied to the foliar surfaces of wheat; usually greater than 30% of the nitrogen from these fertilizers was absorbed when soil applied.