2010 Penn State Short-Season Organic Corn Variety Trial Report

Ear of corn from the short-season organic variety trial. Photo: Mary Barbercheck

By Mark Dempsey and Matt Ryan Department of Crop and Soil Science

The Pennsylvania State University

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Methods

We tested 10 short-season corn varieties for their performance in organic and conventional systems. All varieties were non-GMO and either organic or untreated. The organic test plot was managed by Dave Sandy, PSU Dept. of Crop and Soil Sciences, as part of a research program on reducing tillage in organic crop production systems (<http://agsci.psu.edu/organic/research-and-extension/organic-forage>). The conventional test plots were managed by Jim Breining and John Shaffer, as part of 2010 Pennsylvania Commercial Hybrid Corn Test (http://cornandsoybeans.psu.edu/hybrideval.cfm). See Appendix A for detailed information about each variety. Study sites Our short-season organic corn variety trial was conducted at two sites Penn State’s Russell E. Larson Research and Education Center in Rock Springs, Centre Co., and at the Southeast Ag Research and Extension Center in Landisville, Lancaster Co (Figure 1). One site at Rock Springs was on certified organic land, while the other site at Rock Springs and the site at Landisville were on no-till, conventionally managed land. See Appendix B for soil analysis results from the conventional Rock Springs and the Landisville sites.

• Rock Springs

•  Landisville

Figure 1. Map of Pennsylvania showing site locations, corn maturity zones and the approximate maximum relative maturity of adapted hybrids for full season grain production. Source: <http://agguide.agronomy.psu.edu/cm/sec4/sec43c.cfm>

The Pennsylvania corn maturity zones shown in Figure 1 are based on long-term weather

data, including frost-free growing days and growing degree days. See Table 1 for relative maturity and growing degree ratings for Pennsylvania corn maturity zones.

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Table 1. Approximate relative maturity rating and growing degree days available for Pennsylvania corn maturity zones.

Maturity zone

Approximate relative maturity rating Growing degree days Planting dates

90-95 1,600-1,824 1 96-100 1,825-2,024 May 15-25

101-105 2,025-2,349 2 106-110 2,350-2,499 May 1-15

111-115 2,500-2,724 3 >115 2,725-2,949 April 25-May 7

>115 2,950-3,174 4 >115 ≥3,175 April 15-May 1

Source: <http://agguide.agronomy.psu.edu/cm/sec4/sec43c.cfm> Seedbed preparation

The preceding crop was winter rye at the organic Rock Springs site, corn at the

conventional Rock Springs site, and soybean at the Landisville site. At the organic Rock Springs site, bedded beef cattle manure (22-24 ton/a; N = 24.2 lb/ton; P2O5 = 12.8; K2O = 19.8; see Appendix B) was applied on April 22 and the soil was moldboard plowed the same day, disked with a ‘McConnel’ disk on May 5, and harrowed with a ‘Perfecta II field cultivator’ on May 26 and June 2 (Appendix C). At the conventional Rock Springs site, corn residue was chopped on May 1, and fertilizer and insecticide were applied May 18 (Appendix C). At the Landisville site, fertilizer was applied immediately before planting (Appendix C). Planting

Corn was planted on June 2, 2010 at the organic Rock Springs site with a ‘Monosem’ 4-

row no-till planter, on May 21, 2010 at the conventional Rock Springs site and April 20, 2010 at the Landisville site with an ‘Almaco TP2’ 4-row planter. Corn was planted at 33,000 seeds/a at all sites. At each site, the trial was arranged in a randomized complete block design. Weed management

At the organic Rock Springs site, blind cultivation was done 6 and 13 days after planting (DAP) with a ‘Kovar’ tine weeder. On June 18, 25, and 29 it was cultivated with a ‘John Deere’ inter-row cultivator, and the site was hand-weeded over a 4 week period in July and August (July 8, 12, 13, and August 3; one quarter of the site per date). At the conventional Rock Springs site, herbicides were applied on May 26 (5 DAP; Appendix C). At the Landisville site, herbicides were applied on May 21 (31 DAP), and the crop was side-dressed with urea ammonium nitrate fertilizer on June 11 (52 DAP; Appendix C). Harvesting

Corn was harvested from the middle two rows of each 4-row plot with an ‘Almaco’ 2-row plot combine at all sites. Corn was harvested on November 12 at the organic Rock Springs site (163 DAP), October 22 at the conventional Rock Springs site (154 DAP), and October 6 at

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the Landisville site (169 DAP). Sample weight and moisture content were measured with on-board scale and moisture sensors. Reported yields were adjusted to 15.5% moisture. Dry-down rates At the organic Rock Springs site moisture content of corn was measured over a 51-day period to quantify dry-down rates for each variety. Measurements were made on September 22, 29, October 7, 14, 21, and November 12 (harvest). On all dates, except the harvest date, two ears of corn were collected randomly from border rows, hand-shucked and homogenized, and moisture was measured for each sample. Average moisture content at time of harvest was used for the final date. These measurements were not replicated at the organic Rock Springs site, and grain moisture was only measured at harvest at the other two locations. Statistical analyses Analysis of variance was used to test for differences in corn yield and grain moisture data among varieties. We used the Tukey method to test for differences among varieties averages with significance set a P = 0.05. Linear regression was used to test relationships between continuous variables (i.e. yield, moisture content, relative maturity rating, dry-down rate). All analyses were performed in SAS v9.2. Results and Discussion Yield comparisons among sites

Rainfall at both sites was below average for much of the growing season, and may have caused water stress during critical reproductive growth stages, especailly for corn planted in April and May (Figure 2). Across all varieties, corn yield was greatest at the organic Rock Springs site (average = 169 bu/a; standard error = 3 bu/a), intermediate at the conventional Rock Springs site (average = 143 bu/a; standard error = 4 bu/a), and lowest at the Landisville site (average = 124 bu/a; standard error = 7 bu/a). The difference in average yield at the two Rock Springs sites was likely due to planting date and soil fertility. Corn at the conventional Rock Springs site was planted earlier than corn at the organic site (Appendix A), and may have experienced more water stress. The manure application at the organic site may have also contributed to the relatively higher yields than at the conventional Rock Springs site. At the Landisville site, the relatively low yields are likely attributable to both weed competition and water stress, as weeds were abundant due to the relatively late herbicide application, and there was less than average rainfall during the time when April-planted corn would be in early reproductive growth stages (Figures 2 and 3).

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Figure 2. Total monthly rainfall (inches) from April – November 2010 (solid lines), and April – November historical averages (inches) at Rock Springs and Landisville (dotted lines). Historical averages from 2000-2010 at Rock Springs (source: Penn State Agronomy Farm), and from 1910-2010 at Landisville (source: NOAA, <http://www.ncdc.noaa.gov/oa/ncdc.html>). Yield comparisons among varieties At the organic Rock Springs site, three varieties ‘Blue River 25A16’, ‘Doebler’s UT333X’, and ‘Blue River 30A12’ yielded significantly greater than ‘Viking O89N-80N’, ‘American Organic B916’, and ‘Viking O7292’ (Figure 3, Panel A). However, these varieties did not perform as well at the conventional Rock Springs site. At this site, one of the earliest maturing varieties, ‘Blue River 19K19’ yielded significantly greater than three of the other varieties ‘American Organic B916’, ‘Blue River 25A16’, and ‘Viking O7292’ (Figure 3, Panel B). Surprisingly, the highest yielding variety at the Landisville site was ‘American Organic B916’, which was one of the lowest at the other sites (Figure 3, Panel C). Due to the high level of weeds and variability in variety performance at the Landisville site, we did not interpret data from this site any further.

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b ab ab b a a a ab ab b A

ab ab a bc bc ab ab ab ab c B

bc c ab a c bc bc bc b c C

80 83 84 86 87 89 90 94 95 95 Relative maturity rating Viking Masters

Choice Blue River

AmericanOrganic

Blue River

Doebler’s Blue River

Viking Blue River

Viking Site average

O89N-80N OG-463 19K19 B916 25A16 UT333X 30A12 O39-

94N 36K71 O7292

Figure 3. Average corn yield (bu/a) across varieties at the organic Rock Springs site (A), the conventional Rock Springs site (B) and the Landisville site (C). Relative maturity ratings (days to maturity) are listed above variety names. Within each site, similar lowercase letters above bars indicate no significant difference (P ≥ 0.05). Error bars are standard error of the average.

When both the organic and conventional Rock Springs sites were analyzed together,

‘Blue River 19K19’ had the greatest average yield. It was the only variety that was statistically different from the low-yielding varieties, which included ‘Viking O89N-80N’, ‘American Organic B916’, and ‘Viking O7292’ (Figure 4). Statistical significance is indicated with letters above each bar in Figure 4. Thus, we know the yield for ‘Blue River 19K19’ is statistically different than for those three varieties, because they do not have similar letters above their respective bars.

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bcd abc a cd abc ab ab abc ab d

80 83 84 86 87 89 90 94 95 95 Relative maturity rating Viking Masters

Choice Blue River

AmericanOrganic

Blue River

Doebler’s Blue River

Viking Blue River

Viking Site average

O89N-80N OG-463 19K19 B916 25A16 UT333X 30A12 O39-

94N 36K71 O7292

Figure 4. Average corn yield (bu/a) across varieties for the organic and conventional Rock Springs sites combined. Landisville data were not included. Relative maturity ratings (days to maturity) are listed above variety names. Similar lowercase letters above bars indicate no significant difference (P ≥ 0.05). Error bars are standard error of the average.

Relative maturity rating and yield

We hypothesized that average corn yield would increase with relative maturity rating, however there was no relationship between yield and relative maturity rating at any of the three sites. In addition, we tested for this effect by splitting the 10 varieties into 3 groups (early, mid, and late maturing varieties), and there were no differences in yield among these groups (data not shown).

This result was unexpected and challenges the notion that varieties with longer relative maturity ratings out-yield shorter season varieties. Corn farmers and researchers in other parts of the country have reported similar results with short-season corn. Farmers and researchers have reported that yields of short-season varieties have been equal to or better than those of full-season varieties, and that short-season varieties may require less water over the course of the growing season than full-season varieties (Stalcup 2005, Bruns et al. 2007). In addition, because they are in the field for a shorter period, short-season varieties may fit better into double-cropping rotations (Stalcup 2005).

Moisture content at time of harvest Corn was harvested November 12 at the organic Rock Springs site (163 DAP), October 22 at the conventional Rock Springs site (154 DAP), and October 6 at the Landisville site (169 DAP). Average corn grain moisture at harvest ranged from 16.1-22.1% across varieties and sites (Figure 5). Average grain moisture was highest at the organic Rock Springs site (18.7%), intermediate at the conventional Rock Springs site (17.5%) and lowest at the Landisville site (17.0%). At the organic Rock Springs site, moisture content was lowest for ‘Blue River 19K19’ (16.1%), and highest for ‘American Organic B916’ (21.4%) and ‘Viking O39-94N’ (22.1%). At the conventional Rock Springs site grain moisture was highest for ‘Doebler’s UT 333X’, while grain moisture for most other varieties was similar. At the Landisville site average grain moisture

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was similar for most varieties (16.7-16.9%), except ‘American Organic B916’, which had an average of 17.9% moisture (Figure 5).

bcd bcd d a bc b bc a b cd A

c c bc b c a c ab c c B

C b b b a b b b ab b ab

80 83 84 86 87 89 90 94 95 95 Relative maturity rating Viking Masters

Choice Blue River

AmericanOrganic

Blue River

Doebler’s Blue River

Viking Blue River

Viking Site average

O89N-80N OG-463 19K19 B916 25A16 UT333X 30A12 O39-

94N 36K71 O7292

Figure 5. Average corn grain moisture (percent) across variety at the organic Rock Springs site (A), the conventional Rock Springs site (B) and the Landisville site (C). Relative maturity ratings (days to maturity) are listed above variety names. Within each site, similar lowercase letters above bars indicate no significant difference (P ≥ 0.05). Error bars are standard error of the average.

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When both the organic and conventional Rock Springs sites were analyzed together the

grain moisture was highest for ‘American Organic B916’, ‘Viking O39-94N’ and ‘Doebler’s UT 333X’, while grain moisture for most other varieties lower (Figure 6).

c c c a c ab c a bc c

80 83 84 86 87 89 90 94 95 95 Relative maturity rating Viking Masters

Choice Blue River

AmericanOrganic

Blue River

Doebler’s Blue River

Viking Blue River

Viking Site average

O89N-80N OG-463 19K19 B916 25A16 UT333X 30A12 O39-

94N 36K71 O7292

Figure 6. Average corn grain moisture at harvest across varieties for the organic and conventional Rock Springs sites combined. Landisville data were not included. Relative maturity ratings (days to maturity) are listed above variety names. Similar lowercase letters above bars indicate no significant difference (P ≥ 0.05). Error bars are standard error of the average.

Interestingly, grain moisture was not related to the relative maturity rating at any site (data not shown). We hypothesized that varieties with lower relative maturity ratings would have lower grain moisture at harvest. Despite the lack of correlation between grain moisture and relative maturity rating, we did observe that the three varieties with the earliest relative maturity ratings (‘Viking O89N-80N’; Masters Choice OG-463’; and ‘Blue River 19K19’) consistently had the lowest grain moistures at harvest. This result was statistically significant at the organic Rock Springs site and when all sites were combined. From a management perspective, this suggests that earlier-maturing varieties may be advantageous when growers are trying to minimize expenses associated with corn grain drying. Corn grain moisture was monitored for seven weeks before harvest at the organic Rock Springs site to test for differences among varieties in how fast corn grain dried to a harvestable moisture level. Dry-down rates were determined from the slope of the regression equations for each variety (Figure 7). Because grain moisture decreases over time during drying, the slopes are negative. However, we expressed the dry-down rate as positive number. Thus, lower (more negative) slopes or higher dry-down rates indicate faster grain drying. Dry-down rate was highest for ‘Masters Choice OG-463’ and ‘Blue River 25A16’ (slope: -0.53, -0.50, respectively), and lowest for ‘Viking O7292’ and ‘Viking O89-80N’ (slope: -0.33, -0.23, respectively; Figure 7). This indicates, for example, that ‘Blue River 25A16’ corn grain dried on average 0.5% moisture per day, whereas ‘Viking O89N-80N’ dried on average only 0.23% moisture per day from late September to mid November.

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Figure 7. Change in grain moisture (%) over time at the organic Rock Springs site (September 22 – November 12). The slope (% moisture/day) and y-intercept (estimated % moisture on September 22) of the relationship between grain moisture and sample date are given in parentheses next to variety names. Slopes that are more negative represent faster drying, whereas slopes that are closer to zero represent slower drying.

We also evaluated the relationship between yield and dry-down rate. We found a positive correlation between yield and dry-down rate. In other words, varieties with the highest dry-down rates were associated with highest yields, and varieties with lower dry-down rates were associated with lower yields (Figure 8). However, because grain moisture measurements were not replicated, these results should be interpreted with caution. Figure 8. Corn yield (bu/a) plotted against grain dry-down rate (-% moisture/day) at the organic Rock Springs site (P = 0.07; R2 = 0.35).

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Acknowledgements We thank Dr. Mary Barbercheck, Jim Breining, Dr. Alyssa Collins, Dr. Bill Curran, Error! Reference source not found., and John Shaffer for their assistance with trial implementation and data collection. We also thank Brian White at Albert Lea, Art Scheele at American Organic, Luke Howard at Blue River, Doug Messersmith at Doebler’s, and Ryan Carter at Masters Choice for donating material and assisting with variety selection. Disclaimer Where names of seed companies, varieties, or trade names appear, no discrimination is intended, and no endorsement by Penn State is implied. References Stalcup, L. 2005. Short-Season Corn Works. Online. Corn and Soybean Digest

<http://cornandsoybeandigest.com/short-season-corn-works> Bruns, H. A., Abbas, H. K., Mascagni, H. J., Jr., Cartwright, R. D., and Allen, F. 2007.

Evaluations of short-season corn hybrids in the Mid-South USA. Online. Crop Management <http://ddr.nal.usda.gov/bitstream/10113/12086/1/IND44030788.pdf>

Appendices Appendix A. Variety descriptions from online seed catalogs. American Organic B916

85-87 day relative maturity rating. No seed treatment indicated. “Excellent grain quality, excellent yield for maturity, very good late season plant health, wide range of adaptability. Replaces B38, starts and finishes strong, excellent agronomics, good ear picking.” <http://www.american-organic.com/index.php?page=products&prod=40> Contact information: American Organic, PO Box 385, Warren IL 61087; Ph: 866-471-9465; Fax: 815-788-4000; email: art@american-organic.com.

Blue River 19K19

84 day relative maturity rating. Seed treated with ‘Guardian 3’. “Very good early season vigor, widely adapted, strong late-season plant integrity, potential for dual-purpose use.” Online information no longer available for this variety. Contact information: Blue River Hybrids Organic Seed, 27087 Timber Rd, Kelley IA 50134; Ph: 800-370-7979; Fax:515-233-3069; email: info@blueriverorgseed.com.

Blue River 25A16

87 day relative maturity rating. Seed treated with ‘Guardian 3’. “Well suited to northern environments, strong yield potential, strong stalks, good performance under heat stress.” <http://www.blueriverorgseed.com/products-seed-coating/organic-seed-corn-80-88-day.aspx> See above for contact information.

Blue River 30A12

90 day relative maturity rating. Seed treated with ‘Guardian 3’.

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Appendix A, continued. “Best performance in central and eastern regions, healthy plants with big ears, girthy, semi-flex ears, fast fall dry-down.” <http://www.blueriverorgseed.com/products-seed-coating/organic-seed-corn-90-99-day.aspx>. See above for contact information.

Blue River 36K71 95 day relative maturity rating. Seed treated with ‘Guardian 3’. “Wide leaves result in good canopy cover, very good ear flex for yield stability, heat and drought tolerant, fall dry down above average.” <http://www.blueriverorgseed.com/products-seed-coating/organic-seed-corn-90-99-day.aspx>. See above for contact information.

Doebler’s UT333X 89 day relative maturity rating. Untreated conventional seed. “With exceptional emergence and seedling vigor, it produces tall, high yielding product for grain or quality silage. A flex ear hybrid that flowers early with fast dry-down and very good test weight… ” <http://www.doeblers.com/08/08%20UT%20&%20ORGANIC%20brochure.pdf> Contact information: Doebler’s Pennsylvania Hybrids Inc, 202 Tiadaghton Ave, Jersey Shore PA; Ph: 800-853-2676 or 570-753-3210; Fax: 570-753-5302; email: dmesser@doeblers.com.

Masters Choice OG-463

83 day relative maturity rating. No seed treatment indicated. “Excellent emergence and seedling vigor, quick canopy closure, good stress tolerance. Very adaptable east-west and north-south…” <http://www.bestforage.com/corn-hybrids/organic.html> or <http://seedcorn.com/SeedDetails.aspx?SeedID=94> Contact information: Dealers vary by location. See <http://seedcorn.com/FindAStore.aspx> to locate a dealer.

Viking O89-80N

80 day relative maturity rating. Seed treated with ‘Guardian’. “High yield potential on productive soil types, good early season vigor, tall for an early hybrid with very good stalk strength, some flint corn in background; flowers and black-layers early, excellent test weight and grain quality, slower dry-down, best performance on medium to heavy soils in its zone of adaptation.” <http://www.alseed.com/organic_seed/corn/details.php?category=organic_hybrid> Contact information: Albert Lea Seed, 1414 W Main St, PO Box 127, Albert Lea MN 56007; Ph: 800-352-5247;

Viking O39-94N

94 day relative maturity rating. Seed treated with ‘Guardian’. “High yield potential, good stalk strength, average root strength, medium-tall plant with good ear flex, good plant health and grain quality, best performance on productive soils.” <http://www.alseed.com/organic_seed/corn/details.php?category=organic_hybrid> See above for contact information.

Viking O7292

95 day relative maturity rating. Seed treated with ‘Guardian’. “The most widely-planted and successful 95-day genetics in MN and SD over the last 8 years, exceptional root strength and drought tolerance, very good flex ear, good performance at moderate to high populations…not a good choice for late-harvested fields.” <http://www.alseed.com/organic_seed/corn/details.php?category=organic_hybrid> See above for contact information.

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Appendix B. Results from analyses of soil collected from the conventional Rock Springs site (2006), and of soil collected from the Landisville site (2010), followed by results from analysis of manure applied at the organic Rock Springs site (2010).

D-2

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Appendix B, continued.

Lancaster

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Appendix B, continued

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Appendix C. Management timeline for all sites.

Date Organic Rock Springs Conventional Rock Springs Landisville 20-Apr 10-30-10 fertilizer (100 lb/a) Planting (‘Almaco TP2’ 4-row) 22-Apr Manure application (22-24 ton/a) Moldboard plow 1-May Chop residue 5-May Disk 18-May Insecticide (‘Force 3G’, 6 lb/a) 10-30-10 fertilizer (100 lb/a) 45-0-0 urea (400 lb/a + ‘Agrotain’) 21-May Planting (‘Almaco TP2’ 4-row) ‘Aatrex 4L’ (1 qt/a) ‘Steadfast’ (1.5 oz/a) ‘Prowl H2O’ (3 pt/a) Nonionic surfactant (1 qt/100gal) Ammonium sulfate (2 lb/a) 26-May Harrow ‘Aatrex 4L’ (1.3 qt/a) ‘Dual II Magnum’ (1.3 pt/a) ‘Callisto’ (3 oz/a) ‘Roundup WeatherMax’ (1.5 pt/a) 2-Jun Harrow Planting (‘Monosem’ 4-row) 8-Jun Tine weed 11-Jun 32-0-0 UAN side-dressed (170 lb/a)15-Jun Tine weed 18-Jun Inter-row cultivation 25-Jun Inter-row cultivation 29-Jun Inter-row cultivation 8-Jul Hand weed one quarter of site 12-Jul Hand weed one quarter of site 13-Jul Hand weed one quarter of site 3-Aug Hand weed one quarter of site 6-Oct Harvest (‘Almaco’ 2-row combine) 22-Oct Harvest (‘Almaco’ 2-row combine) 12-Nov Harvest (‘Almaco’ 2-row combine)