Organic Corn Variety Trial

Mideast Organic Corn Variety Trial, 2013

By Michael Bomford, Jake Schmitz, and Tony Silvernail

Organic Valley
logoThis material has been adapted from a talk presented at the March 2014 Organic Association of Kentucky (OAK) conference in Berea, KY, and posters presented at the January 2014 meeting of the Southern Sustainable Agriculture Working Group (SSAWG) in Little Rock, AR and the February 2014 meeting of the Midwest Organic and Sustainable Education Service (MOSES) in La Crosse, WI.

Introduction

Organic feed corn prices have fluctuated between $10 and $17 per bushel since 2012, reaching a record high in the fall of 2012 then falling to $11 per bushel in early 2014 (price report PDF). High feed prices represent a barrier to organic livestock production, but also represent an opportunity for organic farmers who are able to grow their own corn.

Organic farmers are required to plant certified organic seed if it is commercially available. Conclusions drawn from conventional variety trials are not necessarily applicable to organic operations. Organic corn variety trials are needed to identify the best varieties available to organic corn growers.


Objectives


Methods

In the summer of 2013, Organic Valley and Kentucky State University coordinated organic corn variety trials on 567 plots spread over 26 certified organic farms in six states (Fig. 1). Seven organic seed suppliers donated seed for the trial. This was the second year of the multi-state on-farm trial.

Growing conditions were good to above average at most locations, with ample rainfall. A cool wet spring delayed planting, and subsequent harvest, in many of the northern locations. Several northern farms that attempted to participate in the study had to be excluded due to late harvest, leading to inadequate grain drying.

Locations

Figure 1. Approximate locations of farms involved in organic corn variety trial. Each participating farm is shown by a red circle.

Thirty-four organic corn varieties (Table 1) were compared for yield and quality parameters (starch, protein, oil, and density). An open-pollinated variety was used as a check at each site. Each corn plot consisted of four rows of corn, running the entire field length. Between 9 and 44 (mean 22) corn plots were planted on each farm. Varieties were assigned to farms, then randomly distributed between available plots on each farm. Plots were managed using standard production practices employed by experienced farm managers. Farms served as replicates; varieties were not replicated on individual farms. Only varieties grown on at least four farms were considered in the analysis.

Most short season varieties were distributed to northern farms, where growing seasons are shorter. A wet spring and late harvest in the northern region of the study area made much of these data unusable, resulting in less replication of short season varieties (n = 4 - 6) than other varieties (n = 10 - 26). Poor drying and mold infestation precluded most quality analysis for these varieties.

Hand harvest was conducted from a 20-foot row section, beginning 20 feet from the end of the second  row for each variety. Yield is reported on a 15.5% moisture basis. Quality analysis was conducted at the Iowa Grain Quality Initiative Lab.

ANOVA was used to test for farm and variety effects on grain yield, density, and content of starch, protein and oil. Means were separated by Tukey's test. Correlations between yield and quality parameters were also examined.


Table 1. Organic corn varieties tested, by supplier and season length
Season Requirement Albert Lea
(AL)
American
Organic

(AO)
Blue River
(BR)
Doebler's
(DB)
Great Harvest (GH) Masterís Choice (MC) Merit Seed
(MS)
Short
(<96
days)


X3G03



OG-4590
OG-4430
O-346
Medium (96-105 days) 0.57-04N
0.6710
0.69-99N
0.79-96N
50-04N
60-01N
3G33
43L96
48B30
51B57


37N94

OG-5090

Full
(>105
days)

0.59-06N
40-07N
53-09N

57L96
67H19
70R50
76H50
N581
N630
N631
5475
56L3
6175
63T1
6543
OG-535
OG-6060
O-646


Results

The average yield for the trial was 159 bu/ac (Fig. 2), the same as the national average corn yield for 2013 (USDA-ERS, 2014). All study sites were organic farms, so no direct comparisons to conventional corn yields were conducted.

Yield varied significantly between farms, ranging from 90 bu/ac in northern Indiana to 231 bu/ac in central Ohio (Fig. 2). Differences between farms were more pronounced than differences between varieties. Ohio yields were higher than Indiana yields, on average, but no other significant differences were detected between states. Higher yielding farms were not clustered in any particular subregion.

Season length was positively correlated with yield (Fig. 3). Each additional day of season length gave an additional bushel of corn per acre, on average.

Top-yielding varieties were (Table 2):

Other top performers included (Table 2):

Grain yield was positively correlated with protein and density, but negatively correlated with starch content (Fig. 4). Starch content was negatively correlated with all other quality parameters. The negative correlation between starch and protein content was particularly pronounced.


Yield by Location

Figure 2. Average yield (bu/ac) of organic corn at each of the trial locations. Means labeled with the same letter do not differ significantly (Tukey's HSD test, a=0.05).


Table 2. Organic corn yield and quality parameters by variety, supplier, and season length.
Click column header to sort column. Click again to reverse order.

Supplier Variety n Season
(days)
Yield*
(bu/ac)
Protein*
(%)
Oil*
(%)
Starch*
(%)
Density*
(g/mL)
Albert Lea 0.6710 13 98 150 abcd 8.0 abcd 4.3 abcd 72.5 abcde 1.28 bcdefg
Great Harvest 5475 25 108 164 abcd 8.8 abc 3.8 defgh 72.1 bcde 1.28 bcd
Great Harvest 6175 10 112 197 a 8.6 abcd 3.8 cdefghi 72.4 abcd 1.28 bcdef
Great Harvest 6543 13 113 170 abcd 8.4 abcd 3.8 defghi 72.5 abcd 1.28 bcdef
Albert Lea 0.57-04N 12 104 150 abcd 8.6 abcd 4.1 abcdef 71.8 bcde 1.26 fghi
Albert Lea 0.59-06N 23 106 162 abcd 8.2 bcd 4.2 abc 72.1 bcde 1.26 fgh
Albert Lea 0.69-99N 15 99 153 abcd 8.3 abcd 3.9 abcdefghi 72.1 abcde 1.25 efghi
Albert Lea 0.79-96N 5 96 131 abcde - - - -
Great Harvest 37N4 13 97 157 abcd 9.0 abcd 3.8 abcdefghi 71.9 abcde 1.30 abc
American Organic 3G33 16 97 133 de 8.4 abcd 4.0 abcdefgh 72.0 abcde 1.25 ghi
Albert Lea 40-07N 22 107 168 abcd 8.5 abcd 4.0 abcde 72.3 abcd 1.28 bcdef
Blue River 43L96 21 98 142 bcde 8.9 abcd 3.8 bcdefghi 71.6 bcde 1.26 cdefghi
Blue River 48B30 17 102 155 abcd 8.4 bcd 4.0 bcdefg 72.3 abcd 1.28 bcdef
Albert Lea 50-04N 21 104 157 abcd 8.0 cd 3.7 fghi 72.9 ab 1.26 defgh
Blue River 51B57 22 103 175 ab 8.0 cd 3.7 fghi 72.5 abcd 1.24 i
Albert Lea 53-09N 19 109 149 bcd 8.3 bcd 3.9 bcdefg 72.3 abcd 1.27 cdefgh
Great Harvest 56L3 17 106 162 abcd 9.1 ab 3.7 efghi 72.4 abcd 1.32 a
Blue River 57L96 13 107 137 cde 8.7 abcd 3.8 defghi 71.7 cde 1.25 hi
Albert Lea 60-01N 23 101 162 abcd 8.2 bcd 3.9 cdefg 72.5 abcd 1.28 bcdef
Great Harvest 63T1 13 112 181 ab 8.1 bcd 3.5 i 73.2 a 1.29 bcd
Blue River 67H19 14 113 150 abcd 9.1 ab 4.2 ab 71.1 e 1.27 bcdef
Blue River 70R50 12 114 155 abcd 8.5 abcd 4.1 abcd 71.9 bcde 1.28 bcdef
Blue River 76H50 12 117 158 abcd 8.6 abcd 4.2 abc 71.4 de 1.27 cdefgh
Doebler's N581 21 107 163 abcd 8.8 abc 3.8 defghi 72.3 abcd 1.29 bc
Doebler's N630 26
110 171 abc 8.3 bcd 3.9 cdefg 72.3 abcd 1.26 efgh
Doebler's N631 15 110 175 abcd 8.5 abcd 3.5 hi 72.8 abc 1.28 bcde
Merit Seeds O-346 4 90 150 abcde - - - -
Merit Seeds O-646 23 109 166 abcd 8.6 abcd 4.2 abc 71.8 cde 1.28 bcde
Master's Choice OG-4430 5 94 142 abcde - - - -
Master's Choice OG-4590 6 95 127 bcde 7.4 abcd 3.9 abcdefghi 72.7 abcde 1.23 efghi
Master's Choice OG-5090 21 100 159 abcd 8.3 bcd 4.3 a 71.9 bcde 1.27 bcdef
Master's Choice OG-535 22 107 164 abcd 7.9 d 3.9 cdefgh 72.7 abc 1.25 ghi
Master's Choice OG-6060 23 110 155 abcd 8.3 bcd 3.8 defghi 72.6 abc 1.27 cdefg
Open Pollinated OP 22 110 102 e 9.4 a 3.7 ghi 71.8 cde 1.29 b
American Organic X3G03 4 92 145 abcde - - - -

*Means followed by the same letter within a column do not differ significantly (Tukey's HSD test, a=0.05).

Yield and Season Length
Correlation

Figure 3. Relationship between season length and corn yield.

Quality Parameter
Correlations

Figure 4. Relationships between yield and quality parameters. Density expressed in g/mL; other quality parameters are % of grain weight.

Conclusion

The on-farm studies demonstrate successful organic corn production, with excellent yields from a wide range of organic corn varieties. Most commercially available organic hybrids had higher yields than the open-pollinated variety tested. Full season varieties tended to out-yield short season varieties.

Differences between farms were more pronounced than differences between varieties, suggesting that variety selection is less important than farm management and other farm-specific characteristics.

Farmers must consider both yield and quality parameters when deciding which organic corn varieties to plant. Yields were positively correlated with protein content and grain density, suggesting that high yield does not preclude high quality. Curiously, the open pollinated variety had both the lowest yield and the highest protein content among the varieties tested. Starch content was negatively correlated with yield and all other quality parameters, yet the variety with the highest starch content, Great Harvest 63T1, was also among the top yielders. Careful variety selection, coupled with good farm management, can result in high yields of high quality organic corn.

Further study is needed to identify farm and soil characteristics that contribute to optimal performance of available organic corn varieties.

Follow-up

A similar trial was conducted in 2012. The trial will be repeated in 2014.

Acknowledgments

Thanks to:


Updated 03/27/14


College of Agriculture, Food Science and Sustainable Systems