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Fluid Journal : Spring 2015
14 The Fluid Journal Spring 2015 Nitrogen use efficiency (NUE) in high-yield irrigated corn production systems has many economic and environmental implications. In the sub-humid region of North Central and North East Kansas, risk of in-season N loss is higher than in drier irrigated corn production regions of the Central Plains. Many producers in the region rely on single pre-plant applications of granular urea or anhydrous ammonia fertilizer as the primary N source in irrigated corn production systems. These practices increase the likelihood of N loss, environmental impact, and reductions in profit per acre. The continued conversion of flood irrigated land in Kansas to center pivot irrigation systems presents the opportunity to develop automated systems for advanced N management use of multiple N applications through fertigation, which can potentially reduce environmental impact and increase profit per acre. The recent developments in remote sensing technology have made it possible to improve N recommendations using hand-held or machine-mounted active sensors. Sripada, et. al. (2005) demonstrated that remotely sensed NIR radiance could be used to estimate The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Spring 2015 • Vol. 23, No. 2, Issue #88 A.R. Asebedo, E.A . Adee, and D. B . Mengel Performance of remote sensors is essential in achieving high yields. Summary: Nitrogen use efficiency (NUE) in high-yield irrigated corn production systems has many economic and environmental implications. Many producers in the region rely on single pre-plant applications of granular urea or anhydrous ammonia as the primary N source in irrigated production systems. This practice increases the likelihood of N loss, environmental impact, and reductions in profit per acre. The increasing conversion of irrigated land in Kansas to center pivot irrigation systems presents the opportunity to develop automated systems for advanced N management through fertigation that can potentially increase NUE, reduce environmental impact and increase profit per acre. The purpose of this study was to measure the impact of the relationship between irrigation timing, N rate, and timing of N application on corn grain yield and determine the potential for developing algorithms for fertigation systems. Results indicate that overall performance of the sensors and algorithms used was effective at achieving high yields but has the tendency to overestimate N requirements. In order to optimize sensor based N recommendations for fertigation systems, algorithms must be specifically designed for these systems in order to take advantage of their full capabilities, thus allowing advanced N management systems to be implemented. economic optimum N rates through corn growth stage VT. Improvements in center pivot application technology raise the possibility of using pivot-mounted sensors to control site-specific variable rate N rates across a given field. Hence, it is necessary to understand how to best use this technology to optimize N application practices through fertigation in anticipation of widespread adoption of variable-rate center pivot equipment. Objective The objectives of this study were to: • Measure the impact of the relationship between irrigation timing, N rate, and timing of N application on corn grain yield • Evaluate the potential for developing algorithms designed for fertigation systems. Methodology The study was initiated in 2012 and conducted through the 2014 crop year in cooperation with Kansas producers and Kansas State University Agronomy Experiment Fields. The Scandia and Rossville Experiment Fields were irrigated with a lateral sprinkler irrigation system while the cooperative farmer’s field, located outside Scandia (Scandia Site 2), was flood irrigated. Crop rotations, tillage, cultural practices, and corn hybrids used were representative of each area. Plots. Each field study used small research plots, 10 feet in width by 40 feet in length. Irrigation events were scheduled using the KanSched2 evapotranspiration- based irrigation scheduling tool (http:// mobileirrigationlab.com/kansched2). Applications. Sidedress N applications were made prior to scheduled irrigation events to stimulate an N fertigation system. Application timing methods implemented at each site consisted of single pre-plant application, split application between pre-plant and corn growth stage V-4, and split application between pre-plant and variable treatments based on plant reflectance. Fertilizer needs other than N were applied near planting. Design. Treatments were placed in a randomized complete block design with four replications. Canopy reflectance of corn was measured prior to each irrigation event with focus being on V-10 and R-1 growth stages, respectively. Canopy Nitrogen, Irrigation Timing Key To Higher Corn Yields ▼ DOWNLOAD