Implementing In-season N Application Systems on Corn: Sensors, Spreaders and Logistics Peter Scharf University of Missouri
In-season nitrogen: the best opportunity to diagnose optimal rate
Optimal N rate varies widely Field to field Place to place within a field Color measurements are more accurate than Soil tests Yield Can only be used with in-season N
Optimal fertilizer N rate varies widely among fields 20 on-farm experiments in Missouri with corn after soybean, no manure Optimal N rates were 109, 114, 175, 0, 90, 190, 244, 63, 119, 300, 0, 146, 146, 180, 52, 175, 112, 149, 136, 114 lb N/acre Points out the need to diagnose N rate needed for each field
Optimal N rate varies widely within fields What happens when you apply 150 lb N/acre to the whole field? We studied eight fields this way seven were as variable as this one In one field, average best rate was 65; In another field it was 200 Yes: Minnesota, Kansas, Missouri, Pennsylvania No: Wisconsin
A uniform N rate is usually BOTH under- and over-application
Soil N supply varies widely across fields Yield with no N: Wide yield 0-50 13 to 145 bu/acre 50-100 variability 100-160 160-220
Why do I attribute this yield variability to variable soil N supply? Yield with no N: Wide yield 0-50 13 to 145 bu/acre 50-100 variability 100-160 160-220 Yield with unlimited N: Because adding N 160 to 220 bu/acre reduces variability!
Color measurements are more accurate than soil tests or yield data from 64 fields, 7 states Optimal N Rate 300 250 200 150 100 50 0-50 300 9% predictive ability 250 0 200 5 10 15 Optimal N rate pre-plant soil nitrate to 2', ppm 150 100 16% predictive ability 50 0-50 0 5 10 15 20 25 30 Pre-sidedress soil nitrate to 1, ppm Optimal N rate 250 200 150 100 50 0 4% predictive ability 0 50 100 150 200 250 Yield at optimal N rate
There aren t any decent preplant tests to tell you how much N to apply
Color measurements are more accurate than soil tests or yield Optimal N Rate data from 64 fields, 7 states V5 to V9 (9 to hip high) 54% predictive ability 300 250 200 150 100 50 0-50 0.70 0.80 0.90 1.00 1.10 Relative Chlorophyll Meter Reading
Color sensors: the most accurate & convenient diagnostic tool Controller runs ball valve to change fertilizer rate Computer in cab reads sensors, calculates N rate, directs controller New N rate diagnosis every second New N rate every second sensors
Demonstration program: started in 2004 to help farmers try this technology 137 fields, 2004-2009
We used sensors with anhydrous ammonia sensors
Injecting solution (tractor)
Injecting solution (high-clearance)
Dry N with a cart
Dribbling solution
Dry N with high clearance
Dry N with higher clearance
& Dry N with a boom spreader
Sensor demo outcomes 55 replicated on-farm trials Increased corn yield by 2 bushels/acre Reduced N use by 14 pounds/acre Increased partial profit by $17/acre Reduced surplus N by 27% Based on Missouri interpretations for sensors Works with all N forms, placements
My opinion: sensors a great way to determine additional N inputs with P-based manure rates (so is remote sensing)
Are we risking yield loss with early-season N stress? NO
N timing: no net yield impact from planting until 4 feet tall yield relative to preplant N 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 1 2 4 7 0 4 8 12 16 tassel 20 missouri nebraska oklahoma minnesota iowa growth stage of single or main N applic.
Are we risking yield loss by throwing N over the top and burning leaves? Not with urea
Yield loss to N burn: is it a problem? (average of 7 locations in Missouri, 2003-04) Treatment 1 foot 2 feet 3 feet 4 feet Ammonium nitrate 150 lb N applied broadcast at corn height: 1 8 20 18 28% N solution 9 14 33 61 Urea 0 0 4
Sensor-based N management can be used with: Any N source Any type of applicator Corn 1 foot to 7 feet tall Wheat (just before jointing) Cotton (mid-square stage)
Making money with sensors We re making money in corn: At any growth stage from 1 foot to 7 feet tall Whether we lower or raise N rate relative to the producer s rate At any yield level At any preplant N rate We re losing money when the reference area is bad
Making money with sensors Even easier with program support Natural Resources Conservation Service (USDA) in Missouri: approved for incentive payment since 2006 2006: $60/acre ($20/acre x 3 years) 2007: $38/acre ($19/acre x 2 years) 2008: $73/acre ($36.50/acre x 2 years) Not easy for grain-only farmers to get contracts, weighted toward those who have livestock
Is sensor-based N management Almost ready for prime time? I can make it work when I control everything But I have reservations about what s available commercially Greenseeker: drift problems documented, they claim they re fixed but won t reveal how OptRx: new interpretation system in 2012, very high N rates going out in my observation
This manual is available on my web page
How do I get in-season N applied? Any way is a good way But a fast way is probably better 140 acres/day 600 acres/day 300 acres/day 1200 acres/day
Dry N is the fastest 60 new machines like this in MO/IL/IA in past 6 years = $20 million 600 acres/day Cheap! 300 acres/day Southern pilots want to apply N to your corn 1200 acres/day
but beware of dusty urea Fortunately more domestic production of urea is under construction, should increase availability of intact product Super U spreads beautifully
2013: Far more in-season N than ever before Pioneer agronomist webinar June (mainly IA/MO) On average expected 50% of acres to get in-season N Phone calls July: a dozen consultants, extension agronomists, and retailers in MO/IA/IL On average thought 45% of acres had received inseason N Field day wagons northwest MO in August 22/63 = 35% of corn producers had applied in-season N I don t think it had ever been above 5% before
Comments? Questions?