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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #219243
Title: Development of a Critical Value for Late-Season Nitrogen to Increase Spring Wheat Protein

Author
item Qualm, Ann
item Osborne, Shannon
item GELDERMAN, RON - SOUTH DAKOTA STATE UNIV

Submitted to: Soil/Water Research, Progress Report
Publication Type: Experiment Station
Publication Acceptance Date: 5/2/2007
Publication Date: 5/7/2007
Citation: Weinkauf, A.M., Osborne, S.L., Gelderman, R. 2007. Development of a Critical Value for Late-Season Nitrogen to Increase Spring Wheat Protein. South Dakota State University Soil/Water Research, Progress Report. Available http://plantsci.sdstate.edu/soiltest/datafiles/PR%2006-30.pdf, SOIL PR 06-30.

Interpretive Summary: Producers receiving a premium for spring wheat with a protein content greater than or equal to 14%. Obtaining that protein content can be problematic without proper nitrogen fertilizer management. Sensor-based technologies have been used for predicting yield. The question is whether this technology can be used to determine the protein content in-season for spring wheat. Field studies were conducted in South Dakota in 2003 and 2005. Five N treatments (0, 30, 60, 90, 120 lb N ac-1) were applied pre-plant. In 2003, three varieties (Ingot, Oxen, and Walworth) were tested in Brookings, South Dakota. In 2005, one variety (Briggs) was tested at two sites near Gettysburg, South Dakota. Sensor readings were taken at two separate growth stages using the GreenSeeker Hand Held optical sensor. The sensor measures the reflectance in the red and near infrared (NIR) region of the electromagnetic spectrum. Grain samples were collected at maturity and analyzed for protein content. The readings collected at both growth stages in 2003 and 2005 showed a significant relationship between grain yield, grain protein and N uptake. Using this information a critical normalized difference vegetation index (NDVI) value was determined using the Cate-Nelson procedure. If the NDVI value is below the critical value, N fertilizer could be applied foliar to obtain the protein content necessary to ensure the protein premium.

Technical Abstract: Producers receiving a premium for spring wheat with a protein content greater than or equal to 14%. Obtaining that protein content can be problematic without proper nitrogen (N) fertilizer management. Sensor-based technologies have been used for predicting yield. The question is whether this technology can be used to determine the protein content in-season for spring wheat. Field studies were conducted in South Dakota in 2003 and 2005. Five N treatments (0, 34, 68, 102, 136 kg N ha-1) were applied pre-plant. In 2003, three varieties (Ingot, Oxen, and Walworth) were tested in Brookings, South Dakota. In 2005, one variety (Briggs) was tested at two sites near Gettysburg, South Dakota. Sensor readings were taken at two separate growth stages (Feekes 6 and Feekes 10) using the GreenSeeker Hand Held optical sensor. The sensor measures the reflectance in the red and near infrared (NIR) region of the electromagnetic spectrum. Grain samples were collected at maturity and analyzed for protein content. The readings collected at both growth stages in 2003 and 2005 showed a significant relationship between grain yield, grain protein and N uptake. Using this information a critical normalized difference vegetation index (NDVI) value was determined using the Cate-Nelson procedure. The critical NDVI value needed to ensure optimum protein is 0.80586. If the NDVI value is below the critical value, N fertilizer could be applied foliar to obtain the protein content necessary to ensure the protein premium.