Corn Nitrogen Rates What we are learning about Nitrogen

Paul Sullivan, CCA-ON

Bryan Cook, CCA-ON

Eastern Ontario Crop Conference February 18, 2016

Why is Nitrogen at risk in the environment?

Should I apply all my Nitrogen in the spring and be

done with it?

Corn Growth and Nitrogen Uptake Early

Growth Rapid

Growth Maturing Late Loss

100

75

50

25

0 May June July Aug Sept

Seas

onal

Nitr

ogen

Upt

ake,

%

80% of requirement after V8 - 10

Sidedress

Matching up N supply with N demand

N demand is low

N Demand high 10 lbs per acre/ day

Soil is short of oxygen, crop is not short of nitrogen

Do modern corn hybrids take up more nitrogen

later? Should this impact

nitrogen management?

Corn Hybrids Have Changed N Uptake

Timing Pre-Tassel (lb N/ac)

Post Tassel (lb N/ac)

OLD 101 46

NEW 110 64

• Applied 150 lb N/acre • 60 bu/ac higher yield with new hybrid

Source: Tony Vyn, Illinois

How much response do I get from the first 100 bu/ac of N applied?

What are the advantages and disadvantages of the PSNT ?

(Pre Side Dress Nitrogen Test)

Does the PSNT provide a yield index or a Nitrogen rate?

2015 Pre-Sidedress Nitrogen Soil Test (PSNT)

Expected Yield (Bu/acre) 143 167 191 215 240

Soil Nitrate (ppm) Sidedress Nitrogen N Recommendation (lb N/acre)

5 150 170 190 200 225 10 124 145 160 180 200 13 110 130 145 165 180 15 95 115 135 150 170 20 65 90 105 120 140 23 40 65 95 105 120 25 0 45 70 85 100 30 0 0 0 60 70 33 0 0 0 0 50 35 0 0 0 0 0

Adapted from the Ontario's new PSNT N Recommendations based on soil nitrate concentrations and expected yield

The Ontario Nitrogen Calculator is based on a yield goal prediction of

0.8 lbs/bushel of corn.

Is this a realistic benchmark?

Or, should that number be different in Eastern Ontario?

Can a low rate N strip tell me anything about Nitrogen

management?

234 bu/ac

146 bu/ac

146 bu/ac

241 bu/ac

Method of Determining Delta Yield: Low Rate N Strips

Delta Yield: 234 - 146 = 88 241 - 146 = 95

↑ Delta = larger N management impact

What is the average Delta Yield for response of Nitrogen on Corn in

Eastern Ontario?

Variety Response and Delta Yield with varying N Rates

Delta Yield: Determining N Rate Delta Yield (bu) N Side-Dress Rate (lb/A)

10 25 15 50 20 61 30 80 40 90 50 101 60 110 70 117 80 125 90 132

100 147 110 162

Source: Ontario Corn Nitrogen Estimator

How do you use the PSNT to complement other N recommendation systems?

In your experience, does side dress application of

nitrogen increase corn yields in Eastern Ontario?

Hickling data

High yield environment

Low yield environment

212 bu/ac

201 bu/ac

224 bu/ac

215 bu/ac

Nitrogen increases corn yield. So, with high corn

yields do we need to apply more N?

Corn yield response to soil N capacity -- zero fertilizer N –

Ridgetown 2010-2013

Hooker (UG)

Yield (bu/ac)

Tilled No-Till n=16 observations per mean (4 reps x 4 years) Mean separation within tillage Fisher’s Protected LSD (0.05)

C-C C-S C-S-W C-S-W

rc C-C C-S C-S-W C-S-W

rc

Do you think that splitting Nitrogen twice in the season

(V4 to V8 and V10 to V12) following an early season

application of starter N has a future in Eastern Ontario?

Yield Summary 2015 Y Drop Trials (9 sites)

N-Rate Lbs/ac

Low N Strip Yield

Yield Side Dress

Yield Y Drop

Yield Difference

Delta Yield

Grower Rate 150 163 201 200 -1 38

75% Grower Rate 117 163 196 201 5 38

125% Grower Rate 190 163 203 204 1 41

Low End Nitrogen Rate 44 Lbs/ac Max. Delta Yield 77 Bu/ac Min. Delta Yield 12 Bu/ac

I grow corn following soybeans. I apply about 160 lb. N/acre pre-

plant. If I side dress some of my N, would I be able to reduce my

Nitrogen rate?

I have liquid dairy manure on my farm applied in the fall. I

pre-plant most of my nitrogen now. Is this the best way to

apply N or should I side-dress?

I grow corn on corn on some limited acreage. Should I be applying all my nitrogen pre-plant to make sure the crop

doesn’t run short of Nitrogen if we receive a lot of rainfall in

June?

Headline on Corn, 2011

Fungicide Application