Feasibility of Sensor-Based Nitrogen Fertigation Management in Corn January 8, 2018
Averaged across two years, the sensor-based N fertigation treatment consistently resulted in higher profit and nitrogen use efficiency. The use of fertigation offers the unique capability to minimize N losses by reacting to slight N deficiencies in corn by applying N multiple times throughout the season with lower application rates.
- Check (5 lbs of N/acre as starter only)
- High N Reference (non-N limiting treatment)
- UNL algorithm (current N rate BMP, one time in-season sidedress informed by yield goal and N credits)
- Holland-Schepers (H-S) (sensor-BMP similar to Project SENSE, one time in-season sidedress directed by sensors) (Holland and Schepers, 2010)
- Reactive-fixed fertigation (fertigation directed by sensors: react to deficiency, N rate fertigated is fixed)
- Reactive-model fertigation (fertigation directed by sensors: react to deficiency, N rate fertigated is determined by crop computer model)
- Slow release reactive-model fertigation (initial N applied as polymer coated urea (slow release), fertigation directed by sensors: react to deficiency, N rate fertigated is determined by crop computer model)
- Model-fertigation (not sensor informed, proactive N management is informed by crop model)
- All but Check received an initial base rate of N to maintain N sufficiency until sensors become reliably effective at V8.
- N was applied as UAN with exception of the slow release treatment that received slow release nitrogen as the initial base rate.
- Sensor-based methods use sufficiency index (SI) to indicate level of N stress.
- Research was conducted in 2016 and 2017 at the South Central Ag Lab near Clay Center under sprinkler irrigation/fertigation
- Reactive-fixed fertigation treatment grain yield was not significantly different from that of the High N reference, but used considerably less nitrogen in both site years.
- The one time in-season sidedress application treatments (UNL, H-S) recommended more N compared to reactive-fixed fertigation treatment, but no accompanying gain in grain yield.
- Nitrogen use efficiency (NUE) reported as partial factor productivity (PFP) was highest for the reactive fixed fertigation treatment in both site years.
- Partial profit varied slightly by year. There was no significant difference between the treatment with highest partial profit and that of the reactive fixed fertigation treatment in both site years.
- Averaged across both years, the reactive-fixed fertigation treatment consistently resulted in higher profit and nitrogen use efficiency.
- There was no evidence to suggest use of 0.95 SI as the threshold for application was detrimental to yield.
- In 2016 and 2017 at location SCAL, the sensor-guided reactive-fixed fertigation treatment:
- Had the highest nitrogen use efficiency (partial factor productivity)
- Was among the highest yielding treatments (not significantly lower than any other)
- Had the highest partial profit
- Sensor-based fertigation shows potential to be a new BMP that increases nitrogen use efficiency while maintaining or increasing profit