Nebraska On-Farm Research Corn Seeding Rate Studies 2010-2014

Nebraska On-Farm Research Corn Seeding Rate Studies 2010-2014

April 3, 2015; updated with additional data and charts April 17, 2015

As you make your corn management plans this spring, don't overlook the importance of selecting the right planting rate. On-farm research is an excellent way to identify the correct population for your farming operation. In this article, results are presented for 40 on-farm trials. Net returns to planting rate were most commonly maximized at 34,000 and 28,000 seeds per acre for irrigated and rainfed corn, respectively, when corn was valued at $4 per bushel.

On-farm research is an excellent way to identify the correct population for your farming operation. From 2010 to 2014, growers involved in the Nebraska On-Farm Research Network conducted corn seeding rate studies in non-irrigated and irrigated fields, primarily in the eastern half of Nebraska. They mostly followed one of three planting rate protocols:

On-Farm Research Corn Population Sites
Figure 1. Sites where corn seeding rate studies were conducted as part of the Nebraska On-Farm Research Network.
For more information on corn seeding rates see:

 

For irrigated fields

  • 28K, 32K, 36K, 40K seeds/acre
  • 30K, 34K, 38K, 42K seeds/acre

For non-irrigated fields

  • 18K, 22K, 26K, and 30K seeds/acre

Corn Population Results and Recommendations

Nebraska On-Farm Research Network findings showed trial to trial variation in yield response to increasing populations.  This variation is likely due to a combination of factors, including soil, climate, management, and hybrids.

An interactive tool to view individual yield results by location or year was developed by Nebraska Extension Educator Laura Thompson. You can view the non-irrigated corn population results or the irrigated results. Simply use the buttons on the slide within the tool to navigate.

Irrigated Sites

The maximum economic return for the irrigated sites ranged from 28,000 to 40,000 seeds/acre.  With $4/bu corn prices, the 32,000 to 36,000 seeds/acre most frequently optimized economic return.

Table 1. Location and seeding rates tested for 16 irrigated sites (Figure 1).
Site Year County Seeding Rates
(in thousands seeds/acre)
Hybrid ‡ Most profitable
population
($7/bu corn)†
Yield (bu/ac)
at most profitable
population
($7/bu corn)
Most profitable
population
($4/bu corn)†
Yield (bu/ac)
at most profitable
population
($4/bu corn)
1 2010 Seward 28, 32,36,40 C211-835 36000 224 36,000 224
2 2010 Clay 28, 32,36,40 unknown 40,000 224 36,000 221
3 2011 Hamilton 28, 32,36,40 P 1625 28,000 206 28,000 206
4 2011 Seward 28, 32,36,40 C 209-77VT3 28,000 206 28,000 206
5 2012 Dodge 32, 36, 40 P 1625 40,000 243 40,000 243
6 2012 Dodge 32, 36, 40 P 1395AM 36,000 243 32,000 240
7* 2012 Seward 30, 34, 38, 42 BC 15-80 34,000 209 34,000 209
8 2012 Seward 28, 32,36,40 C 211-82R 36,000 234 36,000 234
9* 2012 Hamilton 30, 34, 38, 42 P 33D47 30,000 231 30,000 231
10 2012 Hamilton 30, 34, 38, 42 DKC 63-87 38,000 251 34,000 248
11 2013 Dodge 32, 36, 40 C 215-52 40,000 242 40,000 242
12 2013 Dodge 32, 37 H 8066 AMX 37,000 263 32,000 260
13 2013 Dodge 32, 37 H 8345 AM 32,000 234 32,000 234
14 1014 Jefferson 32, 36, 40, 44 C 215-52 40,000 243 40,000 243
15 2014 Dodge 32, 36 H 8389 32,000 283 32,000 283
16 2014 Dodge 32, 36 H 8331 36,000 284 36,000 284
Median         36,000   34,000  
* These sites had limited irrigation.
‡ Seed abbreviations = DKC = DEKALB®, C = Channel®, P = Pioneer®, H = Hoegemeyer™, GH = Golden Harvest®, BC = Big Cob Hybrids
† Profitability was calculated using seed corn costs of $250/unit (80,000 kernels/unit).
UNL on-farm research irrigated corn population studies (2010-2014)

When combined across all sites, for each additional 1,000 seeds, 0.7 bu/acre of yield is added (Figure 2).

Non-Irrigated Sites

From 2010 to 2014, 24 non-irrigated sites were studied for corn population (Figure 2). Of these, six sites saw significant yield increases for planting populations above 28,000 seeds/acre. Our non-irrigated studies in eastern Nebraska showed we could plant 24,000 to 30,000 seeds/acre.  However, yield response to seeding rate varied based on rainfall; in years with favorable growing conditions, some sites saw maximum economic returns as high as 40,000 seeds/acre.

Table 2. County location, planting date, harvesting date, and hybrid for 24 non-irrigated corn population research sites.
Site Year County Seeding Rates
(in thousands seeds/acre)
Planting Harvesting Hybrid ‡

Most profitable population
($7/bu corn) †
 

Yield (bu/ac)
at most profitable population
($7/bu corn)
Most profitable
population
($4/bu corn) †
Yield (bu/ac)
at most profitable
population
($4/bu corn)
1 2010 Seward 18, 22, 26 unknown unknown C 211-835 26,000 177 26,000 177
2 2010 Clay 18.8, 22.775, 26.4 unknown unknown P 35F40 22,775 136 22,775 136
3 2010 Cass* 24, 30 4/6/10 9/15/10 DKC 65-63 28,000 150 28,000 150
4 2011 Saunders 26, 28,30 5/5/11 10/22/11 C 210-57STX 30,000 153 28,000 152
5 2011 Saunders 26, 28,30 5/5/11 10/22/11 C212-455STX 30,000 149 30,000 149
6 2011 Cass† 24, 30 5/7/11 10/22/11 DKC 65-63 27,000 123 27,000 123
7 2011 Dodge 24.5, 27 4/28/11 10/14/11 GH 9416 28,000 103 28,000 103
8 2012 Saunders 26, 28, 30 5/11/12 10/8/12 C 212-45STX 28,000 111 28,000 111
9 2012 Saunders 26, 28, 30 5/11/12 10/8/12 C208-71VT2 36,000 182 28,000 176
10 2012 Saunders 24, 28, 32, 36 4/27/12 9/14/12 H 8691 24,500 109 24,500 109
11 2012 Cass† 24, 28, 32, 36 4/21/12 9/7/12 DKC 67-57 24,000 77 24,000 77
12 2012 Dodge 24.5, 27 4/22/12 9/4/12 DKC 63-83 28,000 91 28,000 91
13 2012 Washington 24, 28, 32, 36 4/25/12 9/11/12 DKC 59-88 24,000 90 24,000 90
14 2012 Platte 25, 29 5/5/12 9/18/12 H 7711 25,000 84 25,000 84
15 2012 Platte 25, 29 5/5/12 9/18/12 H 7876 29,000 84 29,000 84
16 2013 Saunders 26, 28, 30 5/15/13 11/2/13 C 212-86STX 30,000 208 30,000 208
17 2013 Saunders 26, 28, 30 11/2/13 11/2/13 C 213-40VT3 30,000 214 30,000 214
18 2013 Saunders 24, 28, 32 5/16/13 unknown H 8691 40,000 284 40,000 284
19 2013 Otoe 28, 32, 36, 40 4/6/13 9/23/13 DKC 64-69 28,000 134 24,000 132
20 2013 Dodge 24, 28, 32, 36 4/28/13 unknown P 1498 28,000 160 24,000 157
21 2014 Lancaster 28, 32, 36, 40 4/22/14 11/8/14 DKC 64-87
RIB
36,000 244 36,000 244
22 2014 Washington 26, 30, 34 5/5/14 11/3/14 DKC 62-98 34,000 208 34,000 208
23 2014 Cass 28, 32, 36, 40 4/1/14 10/27/14 DKC 67-57
RIB
32,000 322 32,000 322
24 2014 Saunders 26, 29, 32 5/4/14 11/8/14 C213-40
VT3PRIB
C 215-81
VT2PRIB
32,000 194 32,000 194
Median             28,000   28,000  
* While not technically irrigated, these sites are located in river-bottom ground with a high water table and may be considered to be naturally sub-irrigated.
‡ Seed abbreviations = DKC = DEKALB®, C = Channel®, P = Pioneer®, H = Hoegemeyer™, GH = Golden Harvest®
† Profitability was calculated using seed corn costs of $250/unit (80,000 kernels/unit).

UNL Dryland Corn Population Study

In limited irrigation situations, UNL research has shown yield losses by backing off populations too far in a dry year. (See CropWatch stories, Corn Populations and Deficit Irrigation and Is a Population Change Warranted in Irrigated Corn Due to Water Constraints?)

Hybrid genetics as well as soil, climate, and management can affect optimal seed rate for a particular situation. We recommend visiting with your dealer as seed companies have determined population calibration curves for each hybrid that may guide your decisions.  Additionally, since the economic optimum planting population may vary from year to year and spatially, we suggest you test recommendations in your own fields. (See Test It for Yourself.)

To see more research results from the Nebraska On-Farm Research Network, visit https://cropwatch.unl.eduresultshome.

Laura Thompson, Extension Educator
Jenny Rees, Extension Educator
Charles Wortmann, Extension Soils Specialist
Keith Glewen, Extension Educator
Gary Zoubek, Extension Educator
On behalf of the Nebraska On-Farm Research Team