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

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).

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.edu/resultshome.

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

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