Short Season Corn vs. Commonly Grown Corn Hybrid Maturities for Planting in Ohio 

ANR-94
Agriculture and Natural Resources
Date: 
02/05/2021
Alexander J. Lindsey, PhD, Assistant Professor, Department of Horticulture and Crop Science, The Ohio State University
Richard Minyo, Research Specialist, Department of Horticulture and Crop Science, The Ohio State University
Allen B. Geyer, Senior Research Associate, Department of Horticulture and Crop Science, The Ohio State University
Peter R. Thomison, PhD, Professor Emeritus, Department of Horticulture and Crop Science, The Ohio State University

Ultra-early Corn: Advantages and Disadvantages

A major challenge to successful cover crop establishment can be the relatively narrow window for planting cover crops after corn harvest in the fall. In Ohio, commonly grown maturities range from 104 to 114 days, which is approximately 2500 to 2800 growing degree days (GDDs). Short-season hybrids, or ultra-early hybrids, are more typically planted in northern U.S. areas (e.g., Michigan and Wisconsin) and are associated with relative maturity and heat unit ratings less than 100 days and 2500 GDDs, respectively. Planting ultra-early corn hybrids that are adapted to shorter growing seasons and earlier fall frost dates in Ohio could result in an earlier corn harvest, without increasing drying costs or affecting grain test weight. Earlier harvest could promote earlier cover crop seeding and establishment success prior to winter. 

In the U.S. Corn Belt, full-season corn hybrids generally produce higher grain yields than short-season hybrids when planted in early April and May (Hicks and Thomison, 2004). The yield advantage of full-season hybrids decreases with later planting dates and may be negligible by mid-June (Baum et al., 2019). Corn breeders improved the agronomic performance of short-season hybrids by making them more competitive with the commonly grown maturities within a zone of adaptation (Troyer, 2000). However, performance data for hybrids with relative maturity ratings less than 100 days is limited and these hybrids are not usually evaluated in the annual OSU Ohio Corn Performance Test (Minyo et al., 2018). The objectives of the test were to compare the agronomic performance and partial economic returns of ultra-early hybrids with commonly grown hybrid maturities. It also assessed how altering harvest date impacted the cover crop growing season and performance of full-season hybrids.

Experimental Locations and Procedures 

Field experiments were conducted on a farm near Bucyrus from 2016 to 2018 and at the Ohio Agricultural Research and Development Center (OARDC) near Wooster from 2017 to 2018. Each experiment was replicated four times with plots grouped by maturity or by maturity and harvest date. The harvest date factor allowed for the assessment of commonly grown maturity hybrids harvested when the ultra-early hybrids achieved harvest moisture, as well as when they achieved normal harvest moisture (approximately 2 to 3 weeks later). 

The ultra-early hybrids represented eight seed company brands: Beck’s, DeKalb, LG Seeds, Pioneer, Rupp, Seed Consultants, Steyer, and Syngenta. They were characterized by relative maturities ranging from 90 to 100 days, which corresponded to GDD ratings of 2056 to 2450. The ultra-early hybrids were the same across sites within each year (Table 1). A common set of five elite commonly grown maturity hybrids was included each year with maturity ratings ranging from 104 to 109 and GDDs of 2530 to 2600. Table 1. Range in relative maturity (days) and growing degree days (GDDs) of the ultra-early and commonly grown maturity hybrids evaluated at Wooster and Bucyrus, OH, 2016 to 2018

Table 1. Range in relative maturity (days) and growing degree days (GDDs) of the ultra-early and commonly grown maturity hybrids evaluated at Wooster and Bucyrus, OH, 2016 to 2018
Year No. of Entries Days GDDs
2016 12 90–95 2170–2430
  19 96–100 2056–2450
2017 14 90–95 2170–2430
  28 96–100 2056–2450
2018 16 90–95 2170–2430
  31 96–100 2056–2450
2016–2018 5 104–109 2530–2600

Commonly grown maturity hybrids planted each year.

Plots were planted at a seeding rate of approximately 34,000 seeds per acre (/A). Table 2 indicates the planting and harvest dates for each test location. Grain was assessed for moisture content and test weight, and all yields were adjusted to 15.5% grain moisture concentration for yield comparisons.

Table 2. Planting and harvest dates for the ultra-early corn hybrid tests at Bucyrus and Wooster, OH, 2016 to 2018
Dates Bucyrus Wooster
Planting 5/24/16
  6/2/17 5/23/17
  5/11/18 5/12/18
Harvest 10/12/16
  10/18/17 & 11/9/17 10/14/17 &10/27/17
  9/29/18 & 10/24/18 9/30/18 & 10/18/18

A second set of common maturity hybrids was harvested on the later date indicated.

Analysis and Return per Acre Assessment

Comparisons between maturity groups for yield, harvest moisture, test weight, and partial return were conducted. Data were combined across sites representing different planting date periods in 2016 and 2017 (late May and early June) and in 2018 (early to mid-May). To calculate cover crop growing season changes associated with harvest date, growing degree day accumulation was calculated using average daily temperature and a base of 39 degrees F (Lawson et al., 2015). Partial return/A ($) was calculated using a corn price of $3.50 per bushel (/bu), a drying cost of $0.03 for each percentage point above 15.5% moisture, and an adjustment for test weight with a $0.02 premium for test weight ≥58 pounds/bu, and a $0.03 deduction per point below 53 pounds/bu (Source: Heritage Cooperative, 2018). 

Grain Yield Impacted by Relative Maturity and Planting Date

Increasing hybrid maturity was associated with greater yields across site years. In mid-May planting dates, the yield increase associated with relative maturity was slightly greater (approximately 2.2 bu/A per day, Figure 1). In late May/early June planting dates, grain yields increased approximately 2.0 bu/A per day of relative maturity (P<.001, Fig. 2). The strength of the relationships between hybrid relative maturity and yield was not strong with the r2 being 0.087 for mid-May planting and 0.226 for late-May/early June planting. This was due in part to the wide range in yields among the ultra-early hybrids with differences that spread from 47 bu/A at Bucyrus in 2016 to 71 bu/A at Wooster in 2018. 
Figure 1. Relationship of corn grain yield to hybrid relative maturity averaged 
across Bucyrus and Wooster test locations when planted in mid-May.

Scatter graph with Grain Yield on vertical axis and Relative Maturity on horizontal axis that illustrates an upward trend.

Figure 1. Relationship of corn grain yield to hybrid relative maturity averaged across Bucyrus and Wooster test locations when planted in mid-May.

Scatter graph with Grain Yield on the vertical axis and Relative Maturity on the lower axis showing an upward trend line.

Figure 2. Relationship of corn grain yield to hybrid relative maturity averaged across Bucyrus and Wooster test locations planted in late May/early June

In the mid-May planting, the ultra-early hybrids (90–100 day) yielded 9.7% less than the commonly grown maturity hybrids. The 90–95 day and 96-100 day hybrids yielded 11.7% and 8.7 % less, respectively, than the commonly grown maturity hybrids (Table 3). Grain moisture of the ultra-early hybrids averaged 18.4% compared to 21.2% for the commonly grown maturity hybrids. The test weight of the ultra-early hybrids was 4.6% greater than the commonly grown maturity hybrids. 

Table 3. Grain yield, moisture, test weight and return for the first harvest dates, mid-May planting dates
Corn Hybrid Maturity
days
Yield
bu/A
Grain Moisture
%
Test Weight
lb/bu
Return
$/A
90–95 224 18.0 56.7 765.97
96–100 231 18.7 56.5 786.95
104–109 253 21.2 54.1 843.30
90–100 229 18.4 56.6 779.81
Maturity Groups
90–95 vs. 96–100 -7.6* -0.7* 0.2 NS -20.98*
90–95 vs. 104–109 -29.7* -3.2* 2.6* -77.33*
96–100 vs. 104–109 -22.1* -2.5* 2.4* -56.35*
Ultra-Early vs. Common
90–100 vs. 104–109 -24.7* -2.7* 2.5* -63.49*

Note: Means and results of the single degree of contrasts are presented. Values for the comparisons denote the difference between tested variables (first named minus second named). An asterisk denotes significance at P < 0.05, and letters NS denote contrast was non-significant (P > 0.05).

In late May/early June plantings, the ultra-early hybrids (90–100 day) yielded 9.3% less than the commonly grown maturity hybrids (Table 4). The 90–95 day and 96–100 day hybrids yielded 13% and 8% less, respectively, than the commonly grown maturity hybrids. Grain moisture averaged 18.5% for the ultra-early hybrids compared to 24.2 % for the commonly grown maturity hybrids. The grain test weight of the ultra-early hybrids was 6.5% greater than the commonly grown maturity hybrids. 

Table 4. Grain yield, moisture, test weight and return for the first harvest dates, late May/early June planting dates
Corn Hybrid Maturity
days
Yield
bu/A
Grain Moisture
%
Test Weight
lb/bu
Return
$/A
90–95 211 18.0 57.5 722.60
96–100 221 18.7 56.6 750.07
104–109 240 24.2 53.3 770.43
90–100 217 18.5 56.9 740.52
Maturity Groups
90–95 vs. 96–100 -9.5* -0.6* 0.9* -27.48*
90–95 vs. 104–109 -28.7* -6.1* 4.1* -47.83*
96–100 vs. 104–109 -19.2* -5.5* 3.2* -20.35 NS
Ultra-Early vs. Common
90–100 vs. 104–109 -22.5* -5.7* 3.5* -29.91*


Note: Means and results of the single degree of contrasts are presented. Values for the comparisons denote the difference between tested variables (first named minus second named). An asterisk denotes significance at P < 0.05, and letters NS denote contrast was non-significant (P > 0.05).

Grain Moisture Impacted by Relative Maturity and Planting Date

Although the grain moisture of the 96–100 day hybrids was greater than that of the 90–95 day hybrids, the difference was small (0.6 to 0.7% points) and the higher yield of 96– 100 day hybrids (8 to 9 bu/A) would likely compensate for the difference in grain moisture. Differences in harvest grain moisture levels among the ultra-early hybrids were not consistent with relative maturity ratings, although the trend indicated an increase in moisture by 0.20 to 0.45% per day of RM increase across all tested hybrids (Figures 3 and 4). Harvest grain moisture levels of several 96–100 hybrids were comparable to or lower than the 90–95 day hybrids; harvest moisture trends within the ultra-early hybrids were only 0.16% or 0.26% increase per day of RM increase in late plantings or mid-May planting, respectively (results not shown). 

Scatter graph showing Grain Moisture (%) on vertical axis and Relative Moisture (days) on the horizontal access with an upward trend line.

 Figure 3. Relationship of corn grain moisture to hybrid relative maturity averaged across Bucyrus and Wooster test locations when planted in mid-May

Scatter graph with Grain Moisture (%) on the vertical axis and Relative Maturity (days on the horizontal axis with an upward trend line

Figure 4. Relationship of corn grain moisture to hybrid relative maturity averaged across Bucyrus and Wooster test locations planted in late May/early June

Economic Return Impacted by Relative Maturity and Planting Date

At the two test sites planted in mid-May, yield and return were greater with 104–109 day hybrids. Harvests were earlier with smaller differences in grain moisture and test weight between ultra-early and commonly grown maturity hybrids contributing to greater returns for the 104–109 day hybrids (Table 3). While yield was greatest for the 104–109 day hybrids when planted in late May/early June, the return/A for the 96–100 day hybrids ($750/A) was not different from the 104–109 day hybrids ($770/A) due mainly to discounts from low test weights and high harvest moisture (Table 4). Performance of the 90–95 day hybrids was consistently below the other maturity groups tested, but their yields were still substantial (averaging 211 bu/A across test locations).

Harvest Date and Cover Crop Growing Season

A relatively small decrease in grain moisture and increase in test weight was observed with later harvesting in the commonly grown hybrid maturity hybrids planted mid-May, which resulted in no change in returns (Table 5). Although yields in did not differ between the early and normal harvest dates for the commonly grown hybrid maturity hybrids when planted in late May/early June (233 vs 236 bu/A), returns were reduced 11% on the earlier harvest date for the late May/early June planting dates, due to discounts from low test weights and high harvest moisture (Table 6).

Table 5. Grain yield, moisture, test weight and return for commonly grown corn maturities, harvest dates (HD) 1 and 2 for mid-May planting dates
Harvest Date Yield
bu/A
Grain Moisture
%
Test Weight
lb/bu
Return
$/A
Late Sept. (HD 1) 253 21.2 54.1 843.30
Late Oct. (HD 2) 255 16.7 57.7 883.98
Contrast
HD1 vs. HD 2 -1.8 NS 4.5* -3.6* -40.68 NS

Note: Means and results of the single degree of contrasts are presented. Values for the comparisons denote the difference between tested variables (first named minus second named). An asterisk denotes significance at P < 0.05, and letters NS denote contrast was non-significant (P > 0.05).       

Table 6. Grain yield, moisture, test weight and return for commonly grown corn maturities, harvest dates (HD) 1 and 2, late May/Early June planting dates
Harvest Date Yield
bu/A
Grain Moisture
%
Test Weight
lb/bu
Return
$/A
Mid-Oct. (HD1) 233 28.8 50.9 709.55
Late Oct./Early Nov. (HD2) 236 20.4 55.5 789.09
Contrast
HD1 vs. HD2 -2.8 NS 8.4* -4.7* -79.55*

Note: Means and results of the single degree of contrasts are presented. Values for the comparisons denote the difference between tested variables (first named minus second named). An asterisk denotes significance at P < 0.05, and letters NS denote contrast was non-significant (P > 0.05).

Growers seeking to ensure successful cover crop establishment may be willing to harvest ultra-early corn at moisture levels higher than those used in this study, especially those in the 2018 field experiments with mid-May planting dates. At higher harvest moisture levels, returns/A for ultra-early hybrids relative to commonly grown maturities would increase. The results suggest that growers would gain days for potential cover crop establishment and growth by planting ultra-early hybrids (Table 7). The earlier harvests afforded by planting ultra-early hybrids provided 210 to 447 more GDDs and 0.68 to 4.36 more inches of precipitation than would have been available following harvest of commonly grown maturities at typical harvest moisture levels.

Table 7. Environmental conditions between harvest dates for the commonly grown maturity hybrids at Bucyrus and Wooster, OH 2017-2018
Year 2017 2018
Location Bucyrus Wooster Bucyrus Wooster
Harvest Date Range 10/18–11/9 10/14–10/27 9/29–10/24 9/30–10/18
Accumulated GDDs 232 210 447 379
Precipitation (in.) 4.36 0.68 2.32 1.63
Days with rainfall in excess of 0.25 in. 5 1 3 1

GDDs calculated using base 39 degrees F (Lawson et al., 2015).

Conclusions

Hybrid evaluations play a key role in selecting high yielding ultra-early hybrids, given the variability in yields evident in these tests. Several ultra-early hybrids produced yields comparable to those of commonly grown hybrid maturity hybrids. Earlier maturity hybrids may incur less drying cost and have higher test weights but may have yield disadvantages compared to the 104–109 day hybrids. After factoring in drying costs, the economic return of the 96–100 day ultra-early hybrids was comparable to the commonly grown maturity hybrids when planted in late May/early June and harvested on the earlier harvest date. The greater economic return of the commonly grown maturity hybrids was reduced when harvested early at grain moisture levels exceeding 24%. This may help in the decision making process when considering changes to relative maturity for late planting. Earlier harvest in this study resulted in substantial gains in GDD and precipitation, which would likely improve cover crop establishment efforts and the benefits gained from this practice. 

Acknowledgments

This project was funded in part through the Ohio Conservation Tillage and Technology Conference Research Mini-Grant Program. The full publication in Crop Forage & Turfgrass Management can be found at acsess.onlinelibrary.wiley.com/doi/10.1002/cft2.20019.

References

Baum, M.E., S.V. Archontoulis, and M.A. Licht. (2019). Planting date, hybrid maturity, and weather effects on maize yield and crop stage. Agronomy Journal, 111, 303–313. doi:10.2134/agronj2018.04.0297 

Heritage Cooperative. (2018). Discount schedule. Retrieved February 19, 2020 from aghost.net/images/E0056502/CORN2018A.pdf

Hicks, D.L. and P.R. Thomison. (2004). Corn management. In Corn: origin, history, technology, and production (C.W. Smith, J. Betran, and E. Runge, Eds.), pp. 481-522. John Wiley & Sons, Inc.

Lawson, A., C. Cogger, A. Barry, and A.M. Fortuna. (2015). Influence of seeding ratio, planting date, and termination date on rye-hairy vetch cover crop mixture performance under organic management. Plos One 10(6): e0129597. doi.org/10.1371/journal.pone.0129597

Minyo, R., A. Geyer, P. Thomison, and D.G. Lohnes. (2018). 2018 Ohio corn performance trials. Department of Horticulture and Crop Science Series 212, The Ohio State University. Retrieved August 19, 2019 from oardc.ohio-state.edu/corntrials/

Troyer, F. (2000). Temperate corn – Background, behavior, and breeding. In Specialty Corns (A.R. Hallauer, Ed.), pp. 393-465. CRC Press.