previous crop and cover crop effects on corn nitrogen...

Previous Crop and Cover Crop Effects on Corn

Nitrogen Response

1Department of Soil, Water, & Climate, 2Southern Research and Outreach Center

MVTL Agronomy Update Meeting

January 30, 2020

New Ulm, MN

Carl Rosen1

Vince Fritz2

Charlie Rohwer2

James Crants1

Matt McNearney1

Background and Topics Covered

• Benefits and risks of a rye cover crop

• Sweet corn N rate, timing, and source study

– motivation for previous crop study

• Previous crop establishment to determine N credits

• Field corn N response following various previous crops

Why Plant Cover Crops?• Provides soil cover for extended period in the fall and spring

• Reduces runoff and wind erosion

• Captures residual nutrients (esp. N) to prevent leaching

• Outcompetes/controls weeds

• Potentially suppresses some insects and diseases

• Adds biomass and carbon (& nitrogen if a legume)

• Stimulates soil microbial activity

• Over time can improve soil aggregation

• Of the non-legume cover crops available, cereal rye is the easiest to establish and grow under Minnesota conditions

https://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition/Text-Version/Nonlegume-Cover-Crops/Cereal-Rye

Cover Crop (Rye) Challenges for Corn

• Short time for seeding and stand establishment

– Seed into corn or soybeans before harvest (timely rain needed)

• Sometimes more diseases and pests

• Poor corn stand; Allelopathy? Lots of debate

– Chemical, physical or biological?

• Yield drag

– Termination date

– C/N ratio

– Environmental conditions

https://agfuse.com/article/how-to-protect-corn-yields-following-cereal-rye

Yield Advantage of Corn Following CC vs. No CC

https://www.iasoybeans.com/upl/downloads/publications/long-term-cover-crop-trials.pdf

15 Sites in Iowa in 2017 and 2018

Termination Date is Important – Illinois Study

https://www.dekalbasgrowdeltapine.com/en-us/agronomy/influence-of-the-timing-of-cereal-rye-cover-crop-termination-on-corn-yield.html

-26 -15 0 +7 Photos taken 6/11

Overall Assessment of a Rye CC for Corn

• Use of a winter rye CC can result in reduced or increased corn yields

• Management is important to maintain yields

• Late termination tends to result in lower yields

– Germination effects

– N effects

– Diseases

– Allelopathy


What About CCs Following Sweet Corn?

• About 120,000 acres grown in MN for processing

• In rotation with soybeans and field corn

• Harvest starts early August until mid-late September

• Time and opportunity to establish a cover crop


Previous N Rate Sweet Corn Study - SROC

• Three hybrids– GSS 1477

– DMC 21-84

– GM Code 646

• Two plant populations– 22,000 plants/A

– 28,000 plants/A

• Two planting dates– May

– June

• Six nitrogen treatments

1. 0 (no N applied),

2. 60 lb N/A applied preplant as urea,



5. 120 lb N/A applied preplant as ESN

(Environmentally Smart Nitrogen,

Agrium Inc.),

6. 120 lb N/A as urea with 60 lb N/A

applied preplant and 60 lb N/A applied

at V6-8.

Green Yield as Affected by N Treatment

and Plant Population Yield increased with

increasing N rate at both

populations;

An N rate between 120 and

180 lb N/A was required

Adequate N is necessary to

support yields at the higher

plant population

No difference in yield due to

N timing or N source

N Uptake as Affected by N Treatment and

Plant PopulationN uptake increased with

increasing N rate at both

populations;

N uptake was greater at the

higher plant population

No difference in N uptake

due to N timing or N source

50

55

60

65

0 50 100 150 200

Pe

rce

nt

of

N u

pta

ke in

sto

ver

N applied (lbs/ac)

Urea

ESN

Split

a

b bc bcd

cd d

Proportion of N in Stover as Affected

by N Treatment

At optimum N rates,

57% to 59% of the

N taken up remains

in the stover

C:N ratio of ~ 32

Overall Summary from Sweet Corn N Study

• Optimal N rate for sweet corn following soybeans in a dryland high OM

soil was between 120 -180 lbs N/A; this is higher than current N

recommendations of 110 lbs N/A

• Split N applications and use of coated urea resulted in similar yields

compared to preplant applied urea

• About 58% of the N taken up by sweet corn was still in the stover at

harvest = 60-70 lbs N/A; C:N ratio ~ 30-40

• Can N rates be lowered in a subsequent corn crop?

Nitrogen Credit Study for Field Corn

• Objectives: – To assess the effect of sweet corn as a previous crop, relative to field

corn and soybean on field corn N response

– To determine the effect of a rye cover following sweet corn on field corn N response

• Can N rates be lowered for field corn if sweet corn is the previous crop? – Currently no N credit given for sweet corn

• First step was to establish the previous crops (and rye cover)

Methods

• Rotation crops established in 2017 & 2018

• Field corn N response was evaluated in 2018 & 2019

• Southern Research and Outreach Center (Waseca);

rainfed conditions

Previous Crops – 2017 and 2018

• Sweet Corn, Syngenta GSS1477– 140 lbs N/A

• Sweet Corn, Syngenta GSS1477 + rye cover crop– 140 lbs N/A

• Field corn, Nutech 5F-503AM (2017); 5F-196AM (2018)– 170 lbs N/A

• Soybean, Asgrow AG1733 (2017); Pioneer P15T46R2 (2018)– 0 lbs N/A

• 4 previous crops x 6 N treatments x 4 replications = 96 plots

101 201 301

0 #N 200 #N 100 #N

102 202 302

150 #N 250 #N 50 #N

103 203 303

100 #N 150 #N 200 #N

104 204 304

50 #N 0 #N 250 #N

105 205 305

100 #N 200 #N 0 #N

106 206 306

150 #N 50 #N 250 #N

107 207 307

150 #N 200 #N 0 #N

108 208 308

100 #N 250 #N 50 #N

109 209 309

0 #N 100 #N 150 #N

110 210 310

50 #N 250 #N 200 #N

111 211 311

150 #N 0 #N 200 #N

112 212 312

250 #N 100 #N 50 #N

113 213 313

150 #N 200 #N 100 #N

114 214 314

250 #N 50 #N 0 #N

115 215 315

100 #N 0 #N 150 #N

116 216 316

200 #N 250 #N 50 #N

117 217 317

250 #N 50 #N 0 #N

118 218 318

150 #N 200 #N 100 #N

119 219 319

50 #N 0 #N 250 #N

120 220 320

150 #N 100 #N 200 #N

121 221 321

150 #N 200 #N 100 #N

122 222 322

50 #N 250 #N 0 #N

123 223 323

0 #N 50 #N 150 #N

124 224 324

100 #N 250 #N 200 #N

125 225 325

0 #N 200 #N 250 #N

126 226 326

100 #N 50 #N 150 #N

127 227 327

250 #N 200 #N 100 #N

128 228 328

0 #N 150 #N 50 #N

129 229 329

200 #N 150 #N 50 #N

130 230 330

250 #N 0 #N 100 #N

131 231 331

200 #N 250 #N 50 #N

132 232 332

150 #N 0 #N 100 #N

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Precipitation and Temperature

Previous Crop Data Results - 2017

Crop Harvest yield Residue dry

yield (T/ac)

Residue N

uptake (lbs/ac;

left in field)

Residue C:N

Field corn 157 ± 16 bu/ac 5.1 ± 0.4 66.9 ±5.7 70.1 ± 4.2

Soybeans 48.2 ± 6.8 bu/ac 2.1 ± 0.1 50.0 ± 3.5 40.3 ± 2.1

Sweet corn 4.5 ± 1.2 T/ac 1.7 ± 0.1 59.7 ± 4.8 25.7 ± 2.5

Previous Crop Data Results - 2018

Crop Harvest yield Residue dry

yield (T/ac)

Residue N

uptake (lbs/ac;

left in field)

Residue C:N

Field corn 183 ± 19 bu/ac 3.7 ± 0.1 44.9 ± 1.6 76.8 ± 4.9

Soybeans 62.7 ± 2.7 bu/ac 2.0 ± 0.1 34.4 ± 4.2 58.8 ± 6.2

Sweet corn 6.2 ± 0.4 T/ac 2.4 ± 0.3 56.1 ± 18.4 40.4 ± 7.7

Rye Cover Crop Establishment & Management

• Sweet corn harvested August 15, 2017 & August 15, 2018

• Rye planted August 30, 2017 & September 11, 2018

• Sprayed with Roundup on May 10, 2018 & May 7, 2019

• Disked in 3 days later

Aug. 15, 2017

No-till grain drill

Sept. 7, 2017

Oct. 10, 2017

April 10, 2018

April 25, 2018

May 10, 2018

May 18, 2018

May 7, 2019

Results: Soil Nitrate-N (0-2 ft)

Fall 2017 & Spring 2018

CropFall 2017 nitrate-N

(ppm)

Spring 2018 nitrate-N

(ppm)

Field corn 2.8 ± 1.1 3.9 ± 0.6

Soybeans 3.8 ± 0.3 6.5 ± 2.8

Sweet corn 7.5 ± 0.9 6.4 ± 2.0

Sweet corn + rye 2.2 ± 0.4 3.1 ± 0.9

Soil Nitrate-N (0-2 ft)

Fall 2018 & Spring 2019

CropFall 2018 nitrate-N

(ppm)

Spring 2019 nitrate-N

(ppm)

Field corn 7.1 ± 1.0 8.7 ± 1.5

Soybeans 6.9 ± 1.2 8.1 ± 1.1

Sweet corn 5.8 ± 1.4 7.9 ± 1.9

Sweet corn + rye 6.9 ± 1.1 6.2 ± 1.2

Rye Dry Biomass and N Uptake (May 8, 2018)

1618+372 lbs/A

51+7 lbs N/A

C/N = 14

Rye Dry Biomass and N Uptake (May 7, 2019)

1887+779 lbs/A

56+21 lbs N/A

C/N = 14

N Treatments in 2018 & 20191. 0 lb N/A

2. 50 lb N/A

3. 100 lb N/A

4. 150 lb N/A

5. 200 lb N/A

6. 250 lb N/A• P, K, S all applied preplant and

incorporated with the N

Field corn planted:May 18, 2018 and May 15, 2019

101 201 301

0 #N 200 #N 100 #N

102 202 302

150 #N 250 #N 50 #N

103 203 303

100 #N 150 #N 200 #N

104 204 304

50 #N 0 #N 250 #N

105 205 305

100 #N 200 #N 0 #N

106 206 306

150 #N 50 #N 250 #N

107 207 307

150 #N 200 #N 0 #N

108 208 308

100 #N 250 #N 50 #N

fiel

d c

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10 ft

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June 28, 2019

Previous crop - Field Corn Previous crop Sweet Corn

Field Corn N Response 2018 –

Previous Crop Effects on EONR

Rotation cropYield peak

(bu/ac)

EONR

(lbs/ac)

Field corn 185 252

Soybean 202 160

Sweet corn 207 180

Sweet corn + rye 205 161

N application rate (lbs/ac)

250



Rotation cropYield peak

(bu/ac)

EONR

(lbs/ac)

Field corn 191 256

Soybean 215 170

Sweet corn 219 166


250 188

Conclusions

• An N credit can be given when sweet corn is the previous

crop; possibly similar to or slightly less than soybean

• Adding a rye cover crop after sweet corn results in similar

or slightly less N credit than sweet corn or soybean

• N required for field corn following field corn was much

higher than expected

Next Steps• Data on field corn N uptake

from 2019 still to be analyzed

• Rotation crops & rye were grown for a study in 2020

• Plan is to repeat this study if funding is available

October 2019

Thank You & Questions?

Research Funding AcknowledgmentsMidwest Food Products Association

MN Agricultural Fertilizer Research and Education Council



Rotation cropYield plateau

(bu/ac)

EONR

(lbs/ac N)

Field corn 183 249

Soybean 198 144

Sweet corn 205 149




Rotation cropYield plateau

(bu/ac)

EONR

(lbs/ac)

Field corn 192 257

Soybean 211 126

Sweet corn 211 146


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