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United States Department of Agriculture

Agricultural Research Service

Title: Utilization of Existing Technology to Evaluate Spring Wheat Growth and Nitrogen Nutrition in South Dakota

Author
item Osborne, Shannon

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 2006
Publication Date: March 16, 2007
Citation: Osborne, S.L. 2007. Utilization of existing technology to evaluate spring wheat growth and nitrogen nutrition in South Dakota. Communications in Soil Science and Plant Analysis. 38:949-958.

Interpretive Summary: Variable-rate fertilizer technologies for in-season application of nitrogen to winter wheat have been developed, and are in use in the southern Great Plains. Questions arise about the suitability of this technology for spring wheat production in the northern Great Plains. A field experiment was established in Brookings, SD to evaluate the GreenSeeker Hand Held optical sensor (NTech Industries, Ukiah, CA) for predicting in-season nitrogen status on three spring wheat cultivars (‘Ingot’, ‘Oxen’, and ‘Walworth’) across five nitrogen treatments. Nitrogen rates were 0, 30, 60, 90, and 120 lb/ac applied at planting. Sensor readings and plant biomass samples were collected at Feekes 5 (leaf sheaths strongly erect) and Feekes 10 (boot) growth stages. The ability of the sensor readings to predict plant biomass, plant nitrogen nutrition for each sampling date was determined. In general, plant biomass, and plant nitrogen increased with increasing nitrogen rate for both sampling dates. Readings showed a significant relationship with plant biomass and nitrogen nutrition for all varieties. Results suggest that existing sensor-based variable nitrogen technology developed for winter wheat could be utilized in the northern Great Plains for estimating in-season nitrogen need for spring wheat.

Technical Abstract: Sensor-based technologies for in-season application of nitrogen (N) to winter wheat (Triticum aestivum L.) have been developed, and are in use in the southern Great Plains. Questions arise about the suitability of this technology for spring wheat production in the northern Great Plains. A field experiment was established in Brookings, SD to evaluate the GreenSeeker Hand Held optical sensor (NTech Industries, Ukiah, CA) for predicting in-season N status on three spring wheat cultivars (‘Ingot’, ‘Oxen’, and ‘Walworth’) across five N treatments. Nitrogen rates were 0, 34, 68, 102, and 136 kg N ha-1 applied pre-plant as ammonium nitrate. Sensor readings and plant biomass samples were collected at Feekes 6 and Feekes 10 growth stages. The sensor measures reflectance in the red and near infrared (NIR) regions of the electromagnetic spectrum. A normalized difference vegetation index (NDVI) was calculated. The ability of the sensor readings to predict biomass, plant N concentration, and plant N uptake for each sampling date was determined. In general, biomass, plant N concentration, and N uptake increased with increasing N rate for both sampling dates. Readings collected at Feekes 6 and Feekes 10 showed a significant relationship with plant biomass, N concentration and N uptake for all varieties. Plant N uptake and NDVI resulted in a higher regression coefficients compared to biomass and plant N concentration for all varieties. Results suggest that existing sensor-based variable nitrogen technology developed for winter wheat could be utilized in the northern Great Plains for estimating in-season N need for spring wheat.

Last Modified: 9/23/2014