Corn Fertility. Peter Scharf University of Missouri 2018 Regional Corn Meeting Sikeston, December 12

Transcription

1 Corn Fertility Peter Scharf University of Missouri 2018 Regional Corn Meeting Sikeston, December 12

2 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?

3 North Korea: an inadvertent experiment Figure 1. DPRK Fertilizer use and Grain Production Fert 1000 mt/grain mt Soviet collapse begins Fertilizer use Grain need Grain production year

4 North Korea: an inadvertent experiment Figure 1. DPRK Fertilizer use and Grain Production Fert 1000 mt/grain mt Soviet collapse begins 10% died Grain need Grain production Fertilizer use year

5 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

6 Why would corn not have enough N? Lots of rain Lost between application and when the crop needs it

7 Iowa July 2018 lots of rain = N deficiency

8 When does corn need nitrogen? All the way through Most crucial: Thigh high to blister

9 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

10 Does N stress cut back on row number? 11 years continuous corn with zero N Zero N treatment in bushels behind best treatment 0.3 rows behind best treatment It takes massive N deficiency to reduce row number

11 Cumulative yield, bu/ac Sidedress beats preplant 1600 best preplant best sidedress

12 Cumulative yield, bu/ac Sidedress-only ties split best preplant sidedress 0 pre best sidedress sidedress 50 pre

13 corn yield (bu/ac) Corn N timing, Mississippi County 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

14 Don t worry about preplant N (or early deficiency)

15 Yield Injecting UAN paid off; June paid off UAN-dribbled UAN-injected Feb Mar Apr June July 3-year average, 140 lb N/ac, single shot

16 Ammonium nitrate in June won (all 3 years) 3-year average, 140 lb N/ac, single shot

17 Yield 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

18 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

19 N catch 2016 production field

20 Yield was low where N catch was low

21 If you lose N, does it pay to replace it?

22 Rescue N 100 with, 100 without +30 bu 0 bu If you can see it, it s money

23 How can you see it? 88 of these babies went up in February images of this convention building Dec 1-10 Planet.com

24 Corn, rye, and nitrogen: early N stress often seen

25 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! I could not overcome this yield penalty with: In-furrow N Extra sidedress Color-based N rate diagnosis -80

26 N, P, K: What are they like? Nitrogen Phosphorus, Potassium

27 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

28 Questions? Comments? Photo courtesy of Fred Blackmer

29 Yield loss to N burn (average of 7 locations in Missouri, ) Treatment 1 foot 2 feet 3 feet 4 feet Ammonium nitrate 150 lb N applied broadcast at corn height: % N solution Urea But it can look bad enough to make a producer uncomfortable

30 Foliar N for N stress? Product Rate (lb N/ac) Yield response of N-stressed corn CoRoN 15* 31 CoRoN Urea solution Urea + Agrotain (dry) *2 applications of label rate (3 gal/ac) 50 64

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32 Field maps of variability in N need optimal N rates, lb/acre 0 to to EONR, 120 kg N/ha 0 to to to to to to to to 280 A. claypan B. deep loess C. Mississippi delta D. claypan

33 Field maps of variability in N need Deep Loess 2001 Mississippi Delta 2001 Deep Loess 2002 Mississippi Delta EONR, kg N/ha optimal N rates, lb/acre 0 to 80 0 to to to to to to to to to 280

34 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

35 Overview N for corn When? What? Where? How much?

36 Optimal N Rate y = x R 2 = Crop Circle Yellow/Near-Infrared Relative to High N Plots

37 2008: Our first cotton demo : Calibration research, looks great 2008 demo: Saved 45 lb N/acre, looks great!!

38 sensor Sensor-based strips defoliated better October 3 October 4 producer Sensor strip width

39 Cotton sensor demo outcomes 14 on-farm field-scale demonstrations On average: 19 lb/acre more lint 6 lb/acre less N

40 Wheat: topdress N timing wheat yield N timing Jan Feb March Columbia 2005

41 Wheat: topdress N timing 2006

42 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

43 Columbia 2005, 2006 If you must topdress early, use ESN! Anytime LSD (p=0.05) you topdress = urea, use Agrotain!

44 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

45 February N will stimulate new tillers

46 Should I split my spring N? 1 bushel advantage Average of 7 Missouri experiments

47 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)

48 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