300 Bushel Corn is Easy in No-Till Chad Lee, Ph.D. Extension Agronomist University of Kentucky...

300 Bushel Corn is Easy in No-TillChad Lee, Ph.D.Extension AgronomistUniversity of Kentuckyemail: [email protected] website: www.uky.edu/Ag/GrainCrops/

1Chad Lee, University of Kentucky ©, 2009-2011

Chad Lee, University of Kentucky ©, 2009-2011 2

Photo taken by Chris Breeze, downloaded from Flickr

300 bushels in no-tillage, Irrigated


Joel Armistead, Logan County, Kentucky, 2008: 305.91 bu/acre

Name Armistead Farms, 2008Yield, Bu/A 305.91Hybrid DeKalb DKC66-23County Logan CountyPlanting Date 4/17Row Width, inches 30Seeding Rate 36,000Final Stand 35,000Prev. Crop SoybeanP2O5 58K2O 52N 251Split N No, Pre OnlyOther Mg 7lbs, S 2.5 lbs, B 4 lbs, Zn 2.25 lbsSeed Treatment Poncho 250Herbicides Simazine, Phenoxy, Roundup, DegreeInsecticides HeroFungicides HeadlineTillage No-TillPlanter Kinze 2600Harvester CAT Lexion 570R


Name Armistead Farms, 2008Yield, Bu/A 305.91Hybrid DeKalb DKC66-23County Logan CountyPlanting Date 4/17Row Width, inches 30Seeding Rate 36,000Final Stand 35,000Prev. Crop SoybeanP2O5 58K2O 52N 251Split N No, Pre OnlyOther Mg 7lbs, S 2.5 lbs, B 4 lbs, Zn 2.25 lbsSeed Treatment Poncho 250Herbicides Simazine, Phenoxy, Roundup, DegreeInsecticides HeroFungicides HeadlineTillage No-TillPlanter Kinze 2600Harvester CAT Lexion 570R


251.00 lbs N/A

305.91 Bu/A

0.82 lbs fert. N/bu

N Uptake, grain

0.7 lbs/bu

215 lbs N/acre

300 bushels in no-till, rainfed


20 25 30 35 40 450

50100150200250300350 315

2009, Spindletop Farm, Lexington, KY

1,000 seeds/acre

Yield, bu/A

2009, Spindletop Farm4 hybrids: DKC63-42, DKC63-45, DKC64-44 & DKC65-47No-TillLoradale Silt Loam


Name Spindletop Farm, 2009Yield, Bu/A 315.00Hybrid DeKalb DKC63-24, DKC63-45, DKC65-44, DKC65-47County Fayette CountyPlanting Date 4/27Row Width, inches 30Seeding Rate 45,000Final Stand 47,000Prev. Crop SoybeanP2O5 0 (adequate soil test)K2O 0 (adequate soil test)N 160 lbs/ASplit N No, Sidedress Only (V5)Other noneSeed Treatment Poncho 250Herbicides Lexar + glyphosate fb glyphosateInsecticides NoneFungicides NoneTillage No-TillPlanter John Deere 7200Harvester Hege Wintersteiger


Name Spindletop Farm, 2009Yield, Bu/A 315.00Hybrid DeKalb DKC63-24, DKC63-45, DKC65-44, DKC65-47County Fayette CountyPlanting Date 4/27Row Width, inches 30Seeding Rate 45,000Final Stand 47,000Prev. Crop SoybeanP2O5 0 (adequate soil test)K2O 0 (adequate soil test)N 160 lbs/ASplit N No, Sidedress Only (V5)Other noneSeed Treatment Poncho 250Herbicides Lexar + glyphosate fb glyphosateInsecticides NoneFungicides NoneTillage No-TillPlanter John Deere 7200Harvester Hege Wintersteiger

160.00 lbs N/A

315.00 Bu/A

0.51 lbs fert. N/bu

N Uptake, grain

0.7 lbs/bu

221 lbs N/acre

2009, 0 N “check”

117 bu/acre

82 lbs N/acre


NameArmistead Farms, 2008Irrigated

Spindletop Farm, 2009Rainfed

Yield, Bu/A 305.91 315.00

Hybrid DeKalb DKC66-23DeKalb DKC63-24, DKC63-45, DKC65-44, DKC65-47

County Logan County Fayette CountyPlanting Date 4/17 4/27Row Width, inches 30 30

Seeding Rate 36,000 45,000Final Stand 35,000 47,000Prev. Crop Soybean SoybeanP2O5 58 0 (adequate soil test)K2O 52 0 (adequate soil test)N 251 160 lbs/ASplit N No, Pre Only No, Sidedress Only (V5)


NameArmistead Farms, 2008Irrigated

Spindletop Farm, 2009Rainfed

Yield, Bu/A 305.91 315.00

OtherMg 7lbs, S 2.5 lbs, B 4 lbs, Zn 2.25 lbs none

Seed Treatment Poncho 250 Poncho 250

HerbicidesSimazine, Phenoxy, Roundup, Degree

Lexar + glyphosate fb glyphosate

Insecticides Hero NoneFungicides Headline NoneTillage No-Till No-TillPlanter Kinze 2600 John Deere 7200Harvester CAT Lexion 570R Hege Wintersteiger

[(Kernels x Rows) x Ears]/Kernel Size = Bu/Acre

Kernels per Row Rows Kernels

per EarEars per

AcreKernels

per BushelBushels per Acre

33.5 18 603 47000 90000 31530.2 20 604 47000 90000 31537.7 16 603 47000 90000 315


[(Kernels x Rows) x Ears]/Kernel Size = Bu/Acre

Kernels per Row Rows Kernels

per EarEars per

AcreKernels

per BushelBushels per Acre

33.5 18 603 47000 90000 31530.2 20 604 47000 90000 31537.7 16 603 47000 90000 315

43.5 18 783 35000 90000 30539.2 20 784 35000 90000 30535.7 22 785 35000 90000 305


Critical Points in Ear and Kernel Development


Growth Stage What’s Happening

V6 to V8 Rows per ear and ear length start to be determined

V12 to V14 (1 week before R1)

Ovules per row (potential kernels) are determined

R1 to R6 (Silking to Blacklayer)

Actual kernel number and kernel size is determined

Higher Populations = Smaller Plants = More Yields?


15 20 25 30 35 40 45 500.0

5.0

10.0

15.0

20.0

25.0

R² = 0.855035434306336


4 HybridsPolynomial (4 Hybrids)

1,000 seeds/acre

Stalk Diam., mm

20 25 30 35 40 450

50100150200250300350 315


4 Hy-brids

1,000 seeds/acre

Yield, bu/A

If you are going to push populations, you better have good stalk strength.

Question

• Are you willing to spend $170/acre in seed for 45,000 seeds per acre with a chance of getting 300 bushels?


$/bag seeds/acre $/acre $300.00 35000 $131.25 $300.00 45000 $168.75

$ 37.50

Plant-to-Plant Spacing

Row Spacing

(in)Plants /

Acre Plants / Ft

Inches Between

Plants30 30,000 1.7 7.030 35,000 2.0 6.030 40,000 2.3 5.230 45,000 2.6 4.630 50,000 2.9 4.2


Question

• Are you willing to drive 5 mph during planting?


Corn and Temperature

• Optimum temperature– Near 90 F, if

moisture is abundant

– Below 80 F, if moisture is limited

• Stress Temperature– Above 90 F: roots

have difficulty taking up water fast enough


Source: Modern Corn and Soybean Production. 2000. Hoeft, Nafziger, Johnson and Aldrich

Question

• Can you control temperature?


Corn Water Use

• In the Midwest, corn will use about 20 to 24 inches of water per season


Grass-based soil

• In the Midwest, corn will use about 20 to 24 inches of water per season

• Many grass-based loams can hold 10 to 15 inches of water per season.

• Soils with restriction layers may hold 5 inches or less.



Jan Feb Mar Apr May Jun Jul Aug Sep Oct01234567 2009 Rainfall, Spindletop Farm, KY

Precipitation30 yr normal

inches

Jan Feb Mar Apr May Jun Jul Aug Sep Oct0

20

40

60

80

1002009 Average Temperatures, Spindletop Farm, KY

AVG Temp30 Yr Temp

° F



101520253035

3 1

2009 Temperature, Spindletop Farm, KY

Days, 90+ Days, 32-

° F


102030405060

0.00.51.01.52.02.5

2009 Rainfall, Spindletop Farm, KY

% Rain Days Greatest 24 Hr Total

% days inches

Where do you focus, first?

• Seeding uniformity• Seeding rates• Row width• Hybrid selection• N management• Foliar Products


Corn Grain YieldsWoodford County, Kentucky 2007Dry Weather During Seed Fill


Year: 2007 Location: Woodford County FarmHybrid: SS777RR2YGPLPoncho 1250-treated seedPlanting: May 3, 2007

15 20 25 30 35 40 45120

140

160

180

200

220

240

R² = 0.916691118022844

R² = 0.977334215589995

2007, Kentucky, Woodford County

IrrigatedIrrigatedRainfedPolynomial (Rainfed)

Seeding Rate (1,000 seeds per acre)

Grai

n Yi

eld,

bu/

a at

13.

5% m

oist

ure

SS777 RR2YGPLSeeded: May 3No-TillMaury silt loam

Population Effect, CornLexington, 2008-2009, 4 Hybrids, VT3 Hybrids and RRCB Hybrids


15 20 25 30 35 40 45 500

50

100

150

200

250

300

350

Corn Seeding Rates, 2008-2009

2009 YieldsPolynomial (2009 Yields)

Seeding Rate

Yield, bu/acre

Population Effect, CornLexington, 2008-2009, 4 Hybrids, VT3 Hybrids and RRCB Hybrids


15 20 25 30 35 40 45 500

50

100

150

200

250

300

350

Corn Seeding Rates, 2008-2009

2008 YieldsLinear (2008 Yields)2009 YieldsPolynomial (2009 Yields)

Seeding Rate

Yield, bu/acre

Twin Row Planter


Twin Row Corn, Spindletop Farm, KY, 2009


• Three hybrids:– DeKalb, 1 hybrid

• Developed in 30-inch rows

– Nidera, 2 hybrids• Developed in 20-inch rows

Twin Rows, Narrow RowsLexington, KY, 2009


30 in 15 in twin0

50

100

150

200

250

234 208 218

Lexington, KY, 2009

Row Type

Grain Yield, Bu/A

***

30 in 15 in twin02468

101214

9.212.6 11.9

Lexington, KY, 2009

Row Type

Silage Yield, T DM/A

****

Spindletop Farm, Lexington, KYNo-Till Following SoybeanLoradale silt loamSeeded: 27 Apr 200935,000 seeds/ALexar+Glyphosate PRE, no POST

AX820CL and XA1143MG are from Nidera in Argentina (developed in 20-inch rows).DKC62-54 is from Monsanto DeKalb

*, **Significantly different from 30-inch rows at 0.10 and 0.05, respectively.

Twin RowsPalmer Amaranth


Fulton County, KY, 2009Note: Heavy population of Palmer amaranth competing with corn.


single 32 K twin 32 K twin 38 K0

20

40

60

80

100

120

140

160

180

144 141

167

116 117133

Fulton County, KY, 2009

A6522BtCLA6633BtCL

Yiel

d, b

u/A,

com

bine

har

vest

single 32 K twin 32 K twin 38 K0

50

100

150

200

250

187 180 186

155

181

215


A6522BtCLA6633BtCL

Yiel

d, B

u/A,

han

d ha

rves

tCombine Harvest Hand Harvest

A6633 A6522 A6633 A6522Estimates --------------------- p value -------------------single, 32K vs twin, 32K 0.7390 0.3691 0.8357 0.6220single, 32K vs twin, 38K 0.9420 0.0606 0.1442 0.1684twin, 32K vs twin, 38K 0.7490 0.2434 0.1041 0.3781

Twin Rows or Population?Fulton County, KY, 2009

• We cannot conclude if row width or population or both affected yield.

• We can conclude that weeds cause real problems…


25,000 30,000 35,000 0

50

100

150

200

250

R² = 1

R² = 0.86141876352486


A6522BtCLLinear (A6522BtCL)A6632BtCLPolynomial (A6632BtCL)

Ears/Acre

Yiel

d, b

u/A

AgriGold Study, Madisonville, KY, 2009


34 34 38 38 44 44single twin single twin single twin

0

50

100

150

200

250

300

229 239 240 261 236284

ArigGold, Madisonville, KY, 2009

Row Configuration

Yiel

d, B

u/A

Madisonville, KY, 2009Herring FarmsAgriGold A6533Planted: 25-Apr-09Clay loam soilconventional tillage


Pioneer, 2010, Iowa, 2 Locations, 20 Hybrids, 30 vs. twin at 36 and 42K seeds/A.


Narrow Row Corn, KY, 2010

• Yields were 90 to 110 bu/acre

• No difference between row widths.

• Water was the limiting factor.

Corn Row Widths, United States


Corn, Narrow vs. Wide Row Widths

Location

1-TX 2-SC 3-KY 4-IL 5-MO 6-PA 7-IA 8-IA 9-MI 10-MI 11-MI 12-MI 13-WI 14-WI 15-MN 16-MN 17-MN 18-MN 19-MN 20-MN

Yie

ld D

iffe

ren

ce (

%)

-15

-10

-5

0

5

10

15

Down the Road

• Seeding rates (and final populations) will increase over time.

• At some point, narrow rows will make more sense.


Row Spacing (in) Plants / Acre

Inches Between Plants

30 50,000 4.220 50,000 6.315 50,000 8.4

What about Nitrogen?


160.00 lbs N/A

315.00 Bu/A

0.51 lbs fert. N/bu

251.00 lbs N/A

305.91 Bu/A

0.82 lbs fert. N/bu

0 50 100 150 200 250 3000

100

200

300

400

0.7 lbs N / bushel of corn

lbs N/Acre

Yield, bu/A

Nitrogen Use

Boundary Condition• All N applied is taken

up by the plant. No additional N from the soil, atmosphere, etc.

• N applied = N removed

• 0.7 lbs N / bushel of corn

Real World• Fertilizer N is applied. • Some N is lost. • Soil makes some N

available.


MRTN – Maximum Return to N

Corn Nitrogen Removal = 0.7 lb per bushel

181/0.7 = 259 bu/acre

Profitable range 171-190 lbs NSource: Greg Schwab

Iowa Corn following Corn: 89 sites, N at $0.50/lb; corn at $5.60/bu58Chad Lee, University of Kentucky ©, 2009-2011


Source: Greg Schwab



0 50 100 150 200 2500

50

100

150

200

250

300

Economic Optimum N Rate

Economic Optimum N Rate, lbs N/acre

Corn Yield, bu/A

0 50 100 150 200 2500

50

100

150

200

250

300

Economic Optimum N Rate

Economic Optimum N Rate, lbs N/acre

Corn Yield, bu/A


Source: Greg Schwab


89 sites total

MRTN – Maximum Return to NRecommended range 171-190 Using MRTN

89 sites total 21 Sites Within Range

What about The Others?Source: Greg Schwab


Recommended range using 1.2 x Yield (19 lb range)

89 Sites total: 28 Sites Within Range

(Old) Illinois Yield Goal Approach

Source: Greg Schwab


Lessons from the N Rate Calculator

The MRTN method MIGHT NOT improve efficiency

Improvements are possible if you understand the scatter

Environment Past N MgmtPrecipitationPlacement Drainage

LossesVolatilizationImmobilizationDenitrificationLeaching

Source: Greg Schwab


What affects N use/loss?

Environment/Management• Past N Management• Precipitation• N Placement• Soil drainage• Tillage System

Losses

• Volatilization• Immobilization• Denitrification• Leaching


Average Corn Grain Yield Response to Nitrogen and Tillage(1994 - 2008)

40

60

80

100

120

140

0 50 100 150 200 250 300 350

Fertilizer Nitrogen (lb N/acre/yr)

Gra

in Y

ield

(bu/

acre

/yr)

NT

MP

Long-Term No-Till vs Till Plots, Spindletop Farm, Lexington, KY, 1970-2008Data source: John Grove



Table 13. Recommended application of nitrogen (lb N/A), corn.

Previous Crop Tillage1

Soil Drainage Class2

Well-Drained

Moder-ately Well-

Drained Poorly

Drained

Corn, sorghum, soybean, small grain, fallow

Intensive 100-140 140-175 175-200

Conservation 125-165 165-200

1 Intensive tillage has less than 30% residue cover, and conservation tillage has more than 30% residue cover on the soil at planting.

2 Soil drainage class examples are given on page 3.

AGR-1: Lime and Fertilizer Recommendations

If 0.7 lbs N / bu, then max yield is 200 bu/A

If 0.8 lbs N / bu, then max yield is 175 bu/A

N Management

• N source• N timing• N placement• Soil Type• Soil Condition• Weather• Tillage History• Previous Crop(s)• Previous N Management• Realistic Yield Goal


In my Opinion…

Fertilizer N Rate

Question

• Are you willing to apply about 240 lbs N/acre in an attempt to reach 300 bu/acre?– Lack of water will reduce yields– High temperatures will reduce yields


Hybrids with greater NUE?

• Yields have gone up over time. Nitrogen rates have not.

• Either:– Hybrids are more efficient at using N, or– Hybrids do a better job of taking up N, or– Our application methods are losing less N, or– Some combination of the above


Each bushel of corn contains about 0.7 lbs of N. Do we want to change this number?

Define cheap…

• $5 per acre• $10 per acre• $15 per acre


Is this cheap?

Soil-Applied Fertilizers

• KCl about $0.80/lb K2O

• DAP about $0.60/lb P2O5

Foliar Fertilizer• 3-18-18, $9.50/gallon

– About $2.63 /lb K2O

– About $2.63/lb P2O5


Foliar-applied fertilizers are taken up more readily by the plant.

More to the Story…Leaves are not designed to take up large amounts…only a 1 to 2 lbs at a time.You would need multiple foliar applications to do what soil-applied fertilizers and the roots do.


Greg Schwab

Total uptake of selected nutrients


Crop Yield N P K Ca Mg S Cu Mn Zn

Corn 150 164 90 174 28 28 24 0.11 1.6 0.45

Corn 300 328 180 349 56 56 48 0.22 3.2 0.90

2 Qt/Acre = 5 lbs/AcreApplication Rate

Nutrient Analysis 2 qt/a 10 gal/acre% lbs/A lbs/A

N 11% 0.55 11P 8% 0.5 8K 5% 0.25 5B 0.2% 0.01 0.2Cu 0.05% 0.0025 0.05Fe 0.1% 0.005 0.1Mn 0.05% 0.0025 0.05Mo 0.005% 0.00025 0.005Zn 0.05% 0.0025 0.05

Greg Schwab


High yield system for Corn

1. Productive soils (deep, no compaction)2. Adequate, timely rainfall (or irrigation)3. Good genetics (not specific traits)4. Rotate crops5. Plant on time (not necessarily early)6. Adjust pH and fertilize to soil test; adequate N7. Capture nearly 100% sunlight by about R18. Excellent weed control (no trophy-hunting)9. Scout for diseases & insects10.Identify limitations and improve those

High Yield Corn?

• Identify the limitations – In your fields– In your equipment– In your personnel– In your operation


What is your goal?

• Try to find the next 15 to 20 bushels.

• Keep targeting that and you may get to 300.



High yield system for Corn

1. Productive soils (deep, no compaction)2. Adequate, timely rainfall (or irrigation)3. Good genetics (not specific traits)4. Rotate crops5. Plant on time (not necessarily early)6. Adjust pH and fertilize to soil test; adequate N7. Capture nearly 100% sunlight by about R18. Excellent weed control (no trophy-hunting)9. Scout for diseases & insects10.Identify limitations and improve those

Still not happy with your yields?


High Input Protocol for Irrigated Corn• Select a good hybrid (work with your seed rep)• 45,000 seeds/acre (you choose row spacing)• pH, adjusted to soil test• P: 120 lbs P2O5/A above soil test

• K: 120 lbs K2O/A above soil test

• Zn: 10 lbs/A (about 4 lbs/A if applied with starter)• Sulfur: 20 lbs S/A• Boron: 1 lb B/A• Nitrogen: 240 lbs N/A, or more (can be applied in

split applications)• Weed control: 6-inch limit on weeds• Fungicide at V5 + VT/R1 (tassel/silking)• Insecticide: optional



High Input Protocol $/acre45,000 seeds/A $ 37.50 pH, adjusted to soil testP: 120 lbs P2O5/A above soil test $ 113.00 K: 120 lbs K2O/A above soil test $ 54.50 Zn: 10 lbs Zn/A (4lbs/A if applied with starter) $ 34.00 Sulfur: 20 lbs S/A $ 15.00 Boron: 1 lb B/A $ 3.64 N: 240 lbs N/A, or more (can be split applications) $ 24.00 Weed control: prevent summer annuals from getting above 6 inches $ 15.00 Fungicide at V5 and again at VT/R1 (tassel/silking) $ 30.00

Total $ 326.64

Needs replication across fields or farms.

$ 326.64 extra per acre

If $326.64 / acre is too much…

• … and you are comfortable spending $5 / acre


• Then donate that $5/acre to the university research fund and let us help figure out yield limitations.


Dr. Peter ThomisonThe Ohio State University 228 Kottman Hall2021 Coffey RdColumbus, OH 43210

Thank you for your attention!



TOTAL YIELD

Yield Limitations

TOTAL YIELD

Gen

etic

sS

oils

Nu

trie

nts

Wee

ds

Gen

etic

sS

oils

Nu

trie

nts

Wee

ds

TOP TEN:

1. Plant early, use seed treatments, hope no late freeze occurs

2. Pick a hybrid/variety with good yield potential…forget about defensive traits.

3. 20-inch rows, high populations4. Correct pH, add more fertilizer &

manure (don’t worry about regulations on P)

5. Irrigate at night, absolutely no moisture stress; keep plants cool during day


Money is NOT an issue

TOP TENMoney is NOT an issue…page 2

6. Keep temps below 70° F at night during flowering, pollination and seed fill

7. Have at least 120 days for growth & development

8. “Spoon feed” N through the irrigation


TOP TENMoney is NOT an issue…page 3

9. Have very few cloudy days…10.Keep weeds, diseases and insects

out of field…take no prisoners– Weeds: do not let them get above 2

inches– Diseases & Insects: spray every 7 to 10

days from just prior to reproductive development through seed fill

11.Harvest early…about 30% grain moisture


Argentine corn hybrids have more red in the kernels than North American hybrids. Cattle producers prefer to red tint.


How can you separate the noise?

• Look for studies with stats reported. No stats, no predictability.

• If you do a study… replicate the treatments.

• Replicates can be:– In the same field– In separate fields– On separate farms

• We’ll help with the analysis.


A simple “Strip Plot”…

• Tells how you two treatments did. • Without replicates, you have no way to

separate performance from the noise.



Duvick and Cassman, 1999. Crop Sci 39:1622-1630.

Excellent Weed Control

• Weeds about 6” tall will reduce yields.• Allowing weeds to go to seed creates

problems for the next year. • A soil-applied program following by

postemergence applications are usually very good options.


Adequate Fertility

• Soil test! Every 2 years.• 20 acre-increments.• University of Kentucky

follows economic yield response curve. Other labs use a replacement value.

• AGR-1 Lime and Fertilizer Recommendations for Kentucky


University of Kentucky Thresholds (AGR-1)

Crop Nutrient Soil Test (lbs/acre)

Amount to Apply

Corn For Grain P2O5 >60 0

K2O >300 0

Soybean P2O5 >60 0

K2O >300 0

Corn Silage P2O5 >60 0

K2O >420 0


Corn Growth Stages

V33 Collars

Nodal roots active.Growing point below ground

V66 collars

Growing point above ground.Tassel and ear development starting.

V1212 collars

Ear size, kernel size and kernel number being determined.Limits on water and/or nutrients will reduce yields.


Corn Growth Stages

V1515 collars

Rapid growth, about 10 to 12 days before silking.Most sensitive to stress.

VTtassel

Last tassel branch is visible but prior to silking. Complete leaf loss will cause nearly 100% yield loss.


Corn Growth Stages

• Comparing visible collars to actual nodes.• Tassel and ear development start early.


Corn Growth Stages

R1Silking

N and P uptake are rapid.About 50% of total N is taken up after R1.K uptake is nearly complete.Water needed for pollination. Pollination occurs.

R2Blister

Ear size nearly complete.Silks begin to dry out.A miniature corn plant is being formed in each fertilized kernel.


Corn Growth Stages

R4Dough

Kernels have accumulated ½ of total dry weight. Five leaves have formed in the kernel.

R5Dent

Most kernels have dented and are near 55% moisture at start.Starch layer has formed and progresses down the kernel.


Corn Growth Stages

R6Physiological Maturity

Blacklayer has formed at bottom of kernel. Kernel is about 30 to 35% moisture.


Corn Growing Degree Days

• Corn Growing Degree Day• Base 50° F• Max 86° F• Min 50° F

• Calculate average daily temperature (but not going below 50 for the low or 86 for the high)

• Example: Daily low of 66 and high of 90• ((66 + 86)/2) – 50 = 26 GDDs

No higher than 86


• Corn Growing Degree Day• Base 50° F• Max 86° F• Min 50° F

• Calculate average daily temperature (but not going below 50 for the low or 86 for the high)

• Example: – Daily low of 40 and high of 60– ((50 + 60)/2) – 50 = 5 GDDs

No lower than 50


• About 100 to 125 GDDs are required for crop emergence. • About 82 GDDs are required for each collar developed after

emergence. • Example:

– 700 GDDs have accumulated since planting. – 700 – 125 = 575 GDDs since emergence– 575/82 = 7 so, the corn should be close to V7

Corn and Soybean Field Guide, 2010 Edition


Table 1. Normal Range of CEC Values for Common Color/Texture Soil Groups.CEC in Soil Groups Examples meg/100g

Light colored sands Plainfield 3 to 5Bloomfield

Dark colored sands Maumee 10 to 20Gilford

Light colored loams and silt loams Clermont-Miami 10 to 20Miami

Dark Colored loams and silt loams Sidell 15 to 25Gennessee

Dark Colored silty clay loams and silty clays Pewamo 30 to 40

Hoytville

Organic soils Carlisle muck 50 to 100

Source: David Mengel. 1993. AY-238: Fundamentals of Soil Cation Exchange Capacity (CEC). Purdue Univ.


300 Bushel Corn is Easy in No-Till Chad Lee, Ph.D. Extension Agronomist University of Kentucky...

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