Impact of Hybrid Selection, Planting Date, and Seeding Rates on Dryland Corn in Western Nebraska

Figure 1. Field of early-planted corn that burned up due to drought conditions during the early season in 2017. (Photo by Strahinja Stepanovic)
Figure 1. Field of early-planted corn that burned up due to drought conditions during the early season in 2017. (Photo by Strahinja Stepanovic)

Impact of Hybrid Selection, Planting Date, and Seeding Rates on Dryland Corn in Western Nebraska December 14, 2018

Corn is a critical part of dryland crop rotations in western Nebraska and is typically grown either as continuous corn or after wheat in a three-year wheat-corn-fallow rotation. Many farmers prioritize planting irrigated acres first, often delaying planting dryland corn until after the USDA Risk Management Agency’s final planting date (May 25) for full insurance coverage.

The May 25 planting cutoff is applied across Nebraska.  Many corn growers in western Nebraska perceive this policy as unfair due to the shorter growing season and often better grain yield observed in late-planted corn. During the 2017 early season drought, many farmers in Chase County lost their early-planted dryland corn (Figure 1). Others in the region reported better yield of late-planted dryland corn.

In response, this study was designed to re-evaluate the effects of planting date on dryland corn and examine whether hybrid selection and seeding rate recommendations should be reconsidered for late planting dates.

On-farm Strip Trial at Grant

Table 1. Relative maturity and seed price ($/bag) of four corn hybrids used in planting date and seeding rate study conducted near Grant during the 2018 growing season.
BrandHybrid*Relative
Maturity
Price per
bag ($)
DeKalb® DKC51-20RIB 101 263.61
Croplan® 4079SS 100 307.64
Golden Harvest® G03C84-5122-EZ1 103 200.00
Pioneer® P0589AMXT 105 314.16
* Each hybrid was planted at five planting dates (May 1-June 10) and five seeding rates (7,000-23,000 seeds/ac)

A strip trial was conducted at the Henry J. Stumpf International Wheat Center at Grant during the 2018 growing season on a 75-acre field. The predominant soil type at the site was Kuma silt loam, the previous crop was corn, and the trial was managed using UNL recommended no-till practices and fertility program based on 120 bu/ac yield goal.

Four seed corn companies were contacted to provide their best performing dryland corn hybrids (Table 1) for this study. Each hybrid was planted at five planting dates (May 1, May 10, May 20, May 30, June 10) and five seeding rates (7, 11, 15, 19, and 23 thousand seeds/ac). Each combination was replicated three times and planted into a 60 ft x 150 ft strip. The middle 30 ft of each strip was harvested for yield. Marginal net return (MNR; $/ac) was calculated:

MNR = yield (bu/ac) x seed price ($3.33/bu) – seeding rate ($/ac) x seed price ($/ac)

Main Findings

Graph of precipitation at Grant in 2018 and for the 30-year average
Figure 2. Comparison of precipitation and temperature data at Grant for May to October 2018 and the 30-year average.

FIgure 3
Figure 3. Yield (bu/ac) of four corn hybrids as affected by planting date and seeding rate.

Figure 4.
Figure 4. Marginal net return of four corn hybrids as affected by planting date and seeding rate.
  • The 2018 seasonal precipitation (May-October) was 6.5 inches higher than the 30-year average, especially early in the season, leading to very good yield from early-planted corn (Figure 2, Table 2). In contrast, late season precipitation in August and September was below average, causing yield reduction in late-planted corn (Figure 2, Table 2).
  • Yield penalty for planting dryland corn ranged from 0.5-1.0 bu/ac/day, depending on seeding rate (Figure 3, Table 2).
  • Corn responded very well to higher seeding rates (>19,000), especially at early planting dates (early-mid May) while increasing seeding rate beyond 15,000 seeds/ac was seldom economically justified at late planting dates (Table 3, Figures 3-4).
  • Corn hybrid performance varied by planting date and seeding rate (Tables 4-5). The Golden Harvest hybrid performed best (both for yield and profit) at early planting at high seeding rates. The Croplan hybrid performed well with a mid-May planting at seeding rates above 15,000 seeds/ac. The DeKalb hybrid was the most profitable at late planting dates. The Pioneer hybrid performed best with seeding rates of less than 15,000 seeds/ac, regardless of planting date.

Take-Home Messages

Based on our dryland corn data from the 2018 growing season, it is hard to argue against the current RMA statewide final planting date for full insurance coverage. However, 2018 weather patterns may have favored such results. Multi-year evaluation is needed to evaluate corn yield response to planting dates in semi-arid regions impacted by intermittent periods of drought, such as in western Nebraska.

Due to differences in seed price and responses to seeding practices, hybrid selection should be integral to plans for dryland corn production in 2019.

Previous modeling studies by Nebraska Extension Specialists Bob Klein and Drew Lyon showed that a harvest population of 12,500 plants per acre provided the best economic returns in dryland corn production in western Nebraska.

Acknowledgment

We would like to thank Justin Richardson, Nemanja Arsenijevic, and Zaim Ugljic for their efforts in conducting this field study.

Table 2. Yield (bu/ac) of dryland corn averaged over four hybrids as affected by planting date and seeding rate.
Seeding rate
(seeds/ac)
Planting date
1-May6-May11-May16-May21-May26-May31-May5-Jun10-Jun
23,000 114 113 110 109 106 104 99 88 75
21,000 111 110 109 107 105 104 99 87 73
19,000 107 108 107 106 105 103 98 86 71
17,000 103 104 105 103 103 101 97 84 68
15,000 98 99 100 98 99 97 93 80 64
13,000 92 92 93 91 90 90 87 75 60
11,000 84 84 84 81 79 81 79 69 55
9,000 74 74 73 71 69 71 71 62 49
7,000 63 63 62 60 59 62 62 54 43

 

Table 3. Yield (bu/ac) of four corn hybrids [Dekalb DKC51-20RIB (D), Croplan 4079SS (C), Golden Harvest G03C84-4122-EZ1 (GH) and Pioneer P05889AMXT (P)] as affected by planting date and seeding rate.
HybridPlanting date
1-May 6-May 11-May 16-May 21-May 26-May 31-May 5-Jun 10-Jun
23,000 seeds/ac
Dekalb 114 113 110 109 106 104 99 88 75
Croplan 110 111 113 119 123 120 111 99 85
Golden Harvest 116 112 105 98 91 89 85 73 59
Pioneer 114 112 111 112 111 107 99 86 70
21,000 seeds/ac
Dekalb 111 110 109 107 105 104 99 87 73
Croplan 108 109 111 116 120 117 108 94 80
Golden Harvest 112 109 104 97 91 89 85 72 56
Pioneer 109 109 109 110 110 106 99 86 71
19,000 seeds/ac
Dekalb 107 108 107 106 105 103 98 86 71
Croplan 105 106 109 112 116 112 104 89 74
Golden Harvest 107 105 102 96 91 89 84 70 54
Pioneer 105 106 107 108 108 105 98 85 72
17,000 seeds/ac
Dekalb 103 104 105 103 103 101 97 84 68
Croplan 101 102 104 107 110 106 98 84 68
Golden Harvest 102 101 98 94 91 88 82 68 52
Pioneer 102 103 105 106 106 102 96 84 71
15,000 seeds/ac
Dekalb 98 99 100 98 99 97 93 80 64
Croplan 95 96 98 99 101 98 92 78 62
Golden Harvest 95 95 94 90 89 86 80 66 49
Pioneer 100 101 102 102 102 99 92 81 69
13,000 seeds/ac
Dekalb 92 93 93 91 90 90 87 75 60
Croplan 87 88 89 89 89 88 84 71 57
Golden Harvest 87 87 86 85 84 82 76 62 46
Pioneer 97 97 98 97 96 93 88 78 65
11,000 seeds/ac
Decalb 84 84 84 81 79 81 79 69 55
Croplan 78 80 80 78 76 77 75 65 51
Golden Harvest 78 77 77 77 78 76 71 58 42
Pioneer 92 92 93 91 89 87 82 73 60
9,000 seeds/ac
Dekalb 74 74 73 71 69 71 71 62 49
Croplan 69 70 70 67 64 66 65 57 46
Golden Harvest 68 67 68 69 70 70 65 53 39
Pioneer 86 86 86 85 82 81 76 67 56
7,000 seeds/ac
Dekalb 63 63 62 60 59 62 62 54 43
Croplan 60 60 60 56 53 55 56 50 40
Golden Harvest 57 57 58 60 62 62 58 48 35
Pioneer 79 79 80 78 76 74 70 62 51

 

Table 4. The highest yielding corn hybrid for a given planting date and seeding rate during field study at Grant in 2018 [Dekalb DKC51-20RIB (D), Croplan 4079SS (C), Golden Harvest G03C84-4122-EZ1 (GH) and Pioneer P05889AMXT (P)].
Seeding rate
(seeds/ac)
Planting date
1-May 6-May 11-May 16-May 21-May 26-May 31-May 5-Jun 10-Jun
23,000 GH* D C C C C C C C
21,000 GH D C C C C C C C
19,000 GH D C C C C C C C
17,000 D D P C C C C C C
15,000 P P P P P P D P P
13,000 P P P P P P P P P
11,000 P P P P P P P P P
9,000 P P P P P P P P P
7,000 P P P P P P P P P

 

Table 5. The most profitable corn hybrids for a given planting date and seeding rate during a field study at Grant in 2018 [Dekalb DKC51-20RIB (D), Croplan 4079SS (C), Golden Harvest G03C84-4122-EZ1 (GH) and Pioneer P05889AMXT (P)].

Seeding rate
(seeds/ac)
Planting date
1-May 6-May 11-May 16-May 21-May 26-May 31-May 5-Jun 10-Jun
23,000 GH D D C C C C D D
21,000 GH D D C C C C D D
19,000 GH D D C C C C D D
17,000 GH D D C C C D D D
15,000 GH D D P P D D D D
13,000 P P P P P P D D D
11,000 P P P P P P D D D
9,000 P P P P P P P D D
7,000 P P P P P P P P P