Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/18/2008
Publication Date: 6/1/2008
Citation: Scharf, P., Oliveira, L., Vories, E.D., Stevens, G., Dunn, D., Sudduth, K.A. 2008. Managing N with Sensors: Some Practical Issues. Proceedings of the National Beltwide Cotton Conference, January 8-11, 2008, Nashville, Tennessee. 1585-1588. Interpretive Summary: The adoption of precision agriculture technologies for nitrogen (N) management in cotton is lagging behind others, which is unfortunate considering the hikes in N fertilizer costs and the environmental concerns associated with over-fertilization. “On-the-go” equipment-mounted sensors can operate with no time delay between detecting N deficiency and applying fertilizer to correct the problem; however, field calibration research is needed to ensure the cotton reaches its maximum economical yield potential. Field experiments were conducted that showed good potential for accurate on-the-go prediction of N status in cotton at later growth stages. This research will benefit farmers by ensuring that they apply only the N fertilizer that the plant needs, but the general public will also benefit from fewer instances of excess fertilizer application resulting in cases of eutrophication and hypoxia in streams, lakes, and the Gulf of Mexico.
Technical Abstract: Adoption of precision agriculture practices in cotton has been fast for some technologies and slow for others. Nitrogen management is one of the technologies lagging behind, which is unfortunate considering the hikes in N fertilizer costs. “On-the-go” equipment-mounted sensors are one precision technology for determining nitrogen needs in cotton. The beauty of mounting sensors on application equipment is that there is no time delay between detecting N deficiency and applying fertilizer to correct the problem. However, field calibration research is needed to find nitrogen fertilizer response algorithms to allow cotton to reach its maximum economical yield potential. The objective this experiment is to provide cotton growers with information on using equipment-mounted sensors for applying nitrogen in cotton on silt loam, sandy loam, and clay soils. Field experiments were conducted with sensor measurements collected in 10-day intervals from mid-June to late-August. Nitrogen treatments included twelve nitrogen rates/timings. A high-clearance tractor with three multi-spectral sensors mounted on a boom was driven through the plots and data loggers recorded cotton leaf reflectance data. Leaf chlorophyll meter readings and petiole nitrate concentration were collected from the fourth node from the apex. A good potential for accurate on-the-go prediction on N status in cotton was observed with all three sensor types at mid square and early flower growth stages; however, readings at first square were too early to measure N stress in cotton.