Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/2/2006
Publication Date: 11/7/2006
Citation: Weinkauf, A.M., Osborne, S.L., Gelderman, R. 2006. Utilizing Existing Sensor Technology to Develop a Late-Season Critical Value for Spring Wheat Protein. 2006 North Central Extension-Industry Soil Fertility Conference, Des Moines, Iowa, November 7-8, 2006. Interpretive Summary: A premium is paid to producers for spring wheat with a protein content greater than or equal to 14%. 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 of spring wheat. Field experiments were established in 2003 in Brookings, SD and in 2005 near Gettysburg, SD. Three varieties (Ingot, Oxen, and Walworth) were tested in 2003 and one variety (Briggs) was tested in 2005 across five nitrogen treatments. Nitrogen was applied at planting at rates of 0, 30, 60, 90 and 120 lb/ac. Sensor readings were taken using the GreenSeeker Hand Held Optical Sensor at Feekes 6 and Feekes 10 growth stages. Grain samples were taken at the end of the growing season. The Cate-Nelson procedure was used to determine the critical sensor reading that ensures optimum protein content. The critical sensor reading is 0.80586. If the sensor reading is below 0.80586, nitrogen fertilizer can be applied foliar to ensure the protein premium.
Technical Abstract: A premium is paid to producers 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.