Corn Fertility Peter Scharf University of Missouri 2018 Regional Corn Meeting Sikeston, December 12
What s the most important nutrient for corn? Nitrogen! Worldwide, half of crop yield from N fertilizer (except legumes like soybean, dry bean, alfalfa ) Half of the nitrogen in YOUR BODY came from fertilizer Where does fertilizer N come from? What if we didn t have N fertilizer? Does anyone here grow organic crops?
North Korea: an inadvertent experiment Figure 1. DPRK Fertilizer use and Grain Production Fert 1000 mt/grain 10000 mt 800 700 600 500 400 300 200 100 0 Soviet collapse begins Fertilizer use Grain need Grain production 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 year
North Korea: an inadvertent experiment Figure 1. DPRK Fertilizer use and Grain Production Fert 1000 mt/grain 10000 mt 800 700 600 500 400 300 200 100 0 Soviet collapse begins 10% died Grain need Grain production Fertilizer use 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 year
What happens to corn that doesn t have enough N? Leaves are light-colored (low chlorophyll) Bouncing light back to space instead of catching it and turning it into grain All other functions are scaled back
Why would corn not have enough N? Lots of rain Lost between application and when the crop needs it
Iowa July 2018 lots of rain = N deficiency
When does corn need nitrogen? All the way through Most crucial: Thigh high to blister
How necessary is preplant N? Ken Ferrie (Farm Journal): Never let corn have a bad day Ken Ferrie: N deficiency V5 to V8 might cut 18 rows to 14 or 16
Does N stress cut back on row number? 11 years continuous corn with zero N Zero N treatment in 2017 135 bushels behind best treatment 0.3 rows behind best treatment It takes massive N deficiency to reduce row number
Cumulative yield, bu/ac Sidedress beats preplant 1600 best preplant best sidedress 1400 1200 1000 800 600 400 200 0 2006 2008 2010 2012 2014 2016 2018
Cumulative yield, bu/ac Sidedress-only ties split 1600 1400 best preplant sidedress 0 pre best sidedress sidedress 50 pre 1200 1000 800 600 400 200 0 2006 2008 2010 2012 2014 2016 2018
corn yield (bu/ac) Corn N timing, Mississippi County 200 150 100 50 irr. '97 non-irr. '97 irr. '98 non-irr. '98 0 pre 0 Knee-high 6 Chest-high 12 time of single 200 lb N application
Don t worry about preplant N (or early deficiency)
Yield Injecting UAN paid off; June paid off UAN-dribbled UAN-injected 160 140 120 100 80 60 40 20 0 Feb Mar Apr June July 3-year average, 140 lb N/ac, single shot
Ammonium nitrate in June won (all 3 years) 3-year average, 140 lb N/ac, single shot
Yield 180 160 140 120 100 80 60 40 20 0 Urea as good as UAN, July as good as June UAN-injected urea urea + Agrotain Feb Mar Apr June July 3-year average, 140 lb N/ac, single shot
Spring N I like dry with a cart on corn that s 1-2 feet tall Fast Good yield Low risk of loss (NBPT on urea) Need high clearance or air backup
N catch 2016 production field
Yield was low where N catch was low
If you lose N, does it pay to replace it?
Rescue N 100 with, 100 without +30 bu 0 bu If you can see it, it s money
How can you see it? 88 of these babies went up in February 2017 6 images of this convention building Dec 1-10 Planet.com
Corn, rye, and nitrogen: early N stress often seen
60 40 20 0 effect of rye cover on corn yield Effect of rye cover on corn yield average 12 bushel yield penalty 45 Missouri experiments 99.97% probability that yield penalty is real Data acknowledgements: Peter Scharf (13) Kelly Nelson (13) John Lory (10) Tim Reinbott (3) Bruce Burdick (3) Bill Wiebold (3) Thanks for sharing! -20-40 -60 I could not overcome this yield penalty with: In-furrow N Extra sidedress Color-based N rate diagnosis -80
N, P, K: What are they like? Nitrogen Phosphorus, Potassium
You re not going to get in trouble quickly on P & K Most of my on-farm tests for P & K showed no yield boost Future of PK management: automated onfarm trials to put P & K where they re profitable
Questions? Comments? Photo courtesy of Fred Blackmer
Yield loss to N burn (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 But it can look bad enough to make a producer uncomfortable
Foliar N for N stress? Product Rate (lb N/ac) Yield response of N-stressed corn CoRoN 15* 31 CoRoN 50 47 Urea solution 50 61 Urea + Agrotain (dry) *2 applications of label rate (3 gal/ac) 50 64
Field maps of variability in N need optimal N rates, lb/acre 0 to 80 80 to EONR, 120 kg N/ha 0 to 80 120 to 160 80 to 120 160 to 200 120 to 160 160 to 200 200 to 280 200 to 280 A. claypan 2000 4339850 4339750 568650 568750 568850 568950 B. deep loess 2000 4323250 4323150 C. Mississippi delta 2000 4323050 4107720 4107680 256950 257050 257150 257250 257350 257450 257550 D. claypan 2001 4342900 4342840 574900 575000 575100 575200 575300 575400 575500 4322950 4322850 4322750 4322650 4322550 4322450 4322350 491750 491850
Field maps of variability in N need Deep Loess 2001 Mississippi Delta 2001 Deep Loess 2002 Mississippi Delta 2002 4323050 4104850 4322100 4104900 4322950 4104750 4322000 4104800 4322850 4104650 4321900 4104700 4322750 4104550 4321800 4104600 259475 259575 4322650 4322550 4322450 4322350 491960 4104450 4104350 4104250 259200 259300 4321700 4321600 492660 EONR, kg N/ha optimal N rates, lb/acre 0 to 80 0 to 80 80 to 120 80 to 120 120 to 160 120 to 160 160 to 200 160 to 200 200 to 280 200 to 280
How can you find the places that need more? And less? Crop color More accurate than: Yield Soil tests Soil conductivity Computer models? How? Aerial photos/satellite images Applicator-mounted sensors Hand-held meters
Overview N for corn When? What? Where? How much?
Optimal N Rate 250 200 150 100 50 0 y = 209.48x - 197.59 R 2 = 0.70 0.90 1.10 1.30 1.50 1.70 1.90 2.10 2.30 Crop Circle Yellow/Near-Infrared Relative to High N Plots
2008: Our first cotton demo 2006-07: Calibration research, looks great 2008 demo: Saved 45 lb N/acre, looks great!!
sensor Sensor-based strips defoliated better October 3 October 4 producer Sensor strip width
Cotton sensor demo outcomes 14 on-farm field-scale demonstrations On average: 19 lb/acre more lint 6 lb/acre less N
Wheat: topdress N timing 100 80 wheat yield 60 40 20 0 N timing Jan Feb March Columbia 2005
Wheat: topdress N timing 2006
When should I apply my spring N? Answer: March! 20 bushels more than January (2 tests) 5 bushels more than February (10 tests) 8 bushels more than February when yield is above 70 (4 tests) But I can t get it all done in March
Columbia 2005, 2006 If you must topdress early, use ESN! Anytime LSD (p=0.05) you topdress = urea, use Agrotain!
When should I apply my spring N? Answer: March! Exception: Thin stand in February When the stand is thin, tillering has probably been limited by N availability February N will stimulate new tillers
February N will stimulate new tillers
Should I split my spring N? 1 bushel advantage Average of 7 Missouri experiments
Take-home Pre-plant N for corn: Fails if it rains a lot Isn t needed for full yield Late N applications are effective if the corn needs it Injecting UAN pays off (compared to dribbling) Ammonium nitrate is a great N source N over the top is fast (but bad patterns cost yield) The most profitable N rate varies widely in fields Crop color is the best diagnostic (aerial, sensor)
Take-home Leaf color works to diagnose N rate for cotton too Profitable in on-farm tests (both corn and cotton) Just before jointing is the best time for N on wheat But if thinly tillered, greenup N is needed Coated urea (ESN) good if topdressing early NBPT/Agrotain needed on urea at any temperature I have not seen benefits to splitting spring N