Optimizing Nitrogen and Irrigation Timing for Corn Fertigation Applications Using Remote Sensing Ray Asebedo, David Mengel, and Randall Nelson Kansas State University Manhattan, KS

Objectives  Measure the impact of the relationship between irrigation timing, N rate, and timing of N application with corn grain yield  Evaluate the potential for developing algorithms designed for fertigation systems

Experimental Design  Research plots 10’x40’  Randomized complete block design  Four replications  Two irrigated sites at KSU experiment fields  One flood irrigation site with farmer cooperation in 2012 only

Treatment Protocol, 2012 TreatmentN SourceStarter NPre-Plant NIn-Season N RateTotal N Rate 1Urea Urea Urea UAN V4100 5UAN V4180 6UAN V4270 7UAN2040Sensor60+Sensor 8UAN2080Sensor100+Sensor 9UAN20125Sensor145+Sensor 10Check20N/A

Treatment Protocol, Total N Rate Reduced TreatmentN SourceStarter NPre-Plant NIn-Season N RateTotal N Rate 1Urea Urea Urea UAN V480 5UAN V4140 6UAN V4200 7UAN2040Sensor60+Sensor 8UAN2080Sensor100+Sensor 9UAN20120Sensor140+Sensor 10Check20N/A

Sampling Methods  0-6” and 0-24” soil samples prior to planting  Irrigation scheduling made with KanSched2  Canopy reflectance measured at multiple growth stages  Optical Sensor utilized, Trimble Greenseeker  V-10 and R-1  Tucker and Mengel(2010) algorithm utilized for sensor based N recommendations  Harvested with plot combine at KSU Experiment fields. Hand harvested at farmer fields  Combine harvest area, 5’x40’  Hand harvest area, 5’x17.5’

Site Information, Scandia Station Year Soil TypeCrete silt loam Previous CropSoybeans Tillage PracticeRidge Till Corn HybridNA Pioneer P1602 Plant Population (plants/ac) Irrigation TypeLateral Planting Date4/27/20125/16/20135/5/2014 Second Treatment V-46/4/20126/19/20136/19/2014 Third Treatment V-8 through V-106/14/20127/3/2013NA Last Treatment V-16 through R-16/28/2012NA8/4/2014 Harvest Date10/24/201211/1/201311/11/2014

Site Information, Scandia Site 2 Year2012 Soil TypeCarr Fine Sandy loam Previous CropSoybeans Tillage PracticeRidge Till Corn HybridNA Plant Population (plants/ac)32000 Irrigation TypeFlood Planting Date4/27/2012 Second Treatment V-46/4/2012 Third Treatment V-86/14/2012 Last Treatment V-166/26/2012 Harvest Date9/25/2012

Site Information, Rossville Station Year Soil TypeEudora sandy loam Previous CropSoybeans Tillage PracticeConventional Corn HybridPioneer 0876Producers Hybrid 7224 VT3 Plant Population (plants/ac)32000 IrrigationLateral Planting Date4/29/20134/23/2014 Second Treatment V-46/3/20136/6/2014 Third Treatment V-106/25/2013NA Last Treatment V-16 through R-1NA7/8/2014 Harvest Date9/23/20139/17/2014

Results: By Site and By Year

2012, Scandia Site 2 Farmer Cooperative Field TreatmentTiming Method Starter N (lb/a) Preplant N (lb/a) In-Season N (lb/a)Total N Applied (lb/a) Yield (bu/a) LSD Grouping 4Pre-plant/V A 9Pre-plant/Sensor ABC 1Pre-plant ABC 2Pre-plant ABC 3Pre-plant ABC 7Pre-plant/Sensor ABC 8Pre-plant/Sensor ABC 5Pre-plant/V BC 6Pre-plant/V C 10Check C Treatments with same letter are not statistically different at an 0.05 alpha

2012, Scandia Site 2 Farmer Cooperative Field

 Approximately 60 pounds of N per acre was applied through the irrigation water  Low response to applied N  Site not utilized after 2012 due to high NO3-N in irrigation water  Sensor treatments over applied N

2012, Scandia Station TreatmentTiming Method Starter N (lb/a) Preplant N (lb/a) In-Season N (lb/a) Total N Applied (lb/a) Yield (bu/a) LSD Grouping 6Preplant/V A 5Preplant/V A 3Preplant A 9Preplant/Sensor A 8Preplant/Sensor B 2Preplant BC 7Preplant/Sensor BC 1Preplant C 4Preplant/V D 10Check E Treatments with same letter are not statistically different at an 0.05 alpha

2012, Scandia Station

 Split N applications Preplant/V-4 achieved highest yield 187 bu/ac at 180 lbs N/ac  Preplant treatment required 230 lb N/ac to be statistically equal to highest yielding Split treatments  Sensor treatment with 125 lb N/ac at Preplant was able achieve high yield but overestimated N need to attain it

2013, Scandia Station TreatmentTiming Method Starter N (lb/a) Preplant N (lb/a) In-Season N (lb/a) Total N Applied (lb/a) Yield (bu/a) LSD Grouping 5Preplant/V A 8Pre-plant/Sensor AB 4Preplant/V AB 3Pre-plant AB 6Preplant/V AB 7Pre-plant/Sensor AB 2Pre-plant AB 9Pre-plant/Sensor AB 1Pre-plant B 10Check C Treatments with same letter are not statistically different at an 0.05 alpha

2013, Scandia Station

 Overall yields were lower than expected at 179 bu/ac. Expected yields were 250 bu/ac. Likely due to late planting  Low response to applied N  Primary response was to total N rate  Conditions were conducive for mineralization of N  Sensor treatments achieved highest yield group but overestimated the N requirements

2013, Rossville Station TreatmentTiming Method Starter N (lb/a) Preplant N (lb/a) In-Season N (lb/a) Total N Applied (lb/a) Yield (bu/a) LSD Grouping 8Pre-plant/Sensor A 7Pre-plant/Sensor A 9Pre-plant/Sensor AB 6Preplant/V AB 5Preplant/V ABC 2Pre-plant ABC 3Pre-plant BC 4Preplant/V CD 1Pre-plant D 10Check000070E Treatments with same letter are not statistically different at an 0.05 alpha

2013, Rossville Station

 Significant response to applied N  Soil is a deep sandy loam and incurred frequent leaching events, lowering overall yield ranging from bu/ac  Sensor treatments generated the highest yields but only statistically different from lower rate preplant treatments  Results indicate fertigation systems may need to make frequent low rate N applications to satisfy N demand despite water requirements being met or exceeded

2014, Rossville Station TreatmentTiming Method Starter N (lb/a) Preplant N (lb/a) In-Season N (lb/a) Total N Applied (lb/a) Yield (bu/a) LSD Grouping 2Pre-plant A 6Preplant/V AB 5Preplant/V ABC 3Pre-plant ABC 1Pre-plant ABC 7Pre-plant/Sensor ABC 9Pre-plant/Sensor BC 4Preplant/V C 8Pre-plant/Sensor C 10Check D Treatments with same letter are not statistically different at an 0.05 alpha

2014, Rossville Station

 Excellent yields and significant response to N  Clay lense at 24” to 36” depths held up water in the rooting zone, preventing leaching losses. As a result much higher yields were obtained compared to the 2013 Rossville site bu/ac  Sensor treatments were effective at finding 90% economic optimum, achieving 237 bu/ac from 55 lb of applied N/ac

2014, Scandia Station TreatmentTiming Method Starter N (lb/a) Preplant N (lb/a) In-Season N (lb/a) Total N Applied (lb/a) Yield (bu/a) LSD Grouping 6Preplant/V A 3Pre-plant AB 9Pre-plant/Sensor AB 7Pre-plant/Sensor AB 2Pre-plant B 8Pre-plant/Sensor B 5Preplant/V BC 1Pre-plant C 4Preplant/V D 10Check E Treatments with same letter are not statistically different at an 0.05 alpha

2014, Scandia Station

 Excellent yields bu/ac and significant response to applied N  Low N loss  Conducive conditions for mineralized N, resulting in high productivity, 163 bu/ac check  Sensor treatments were effective at determining the optimum N rate (150 lb N/ac) and achieve high yield 231 bu/ac

Potential for Fertigation and Remote Sensing  Would be able to conduct crop monitoring throughout the growing season, thus presenting the possibility to determine the optimize N rate and timing for any given soil and year (weather)  Sensor algorithms must be specifically designed for fertigation systems  Fertigation systems may need to apply N when water requirements have been met or exceeded

2015 So Far

But… Heavy rain created anaerobic conditions Most fields did not need additional N

Questions