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Advanced Cover Cropping Strategies for Organic Food Grain Crop Production Final Report to the New World Foundation’s Local Economies Project
Project Summary
Two cover crop management practices were tested at the Hudson Valley Farm Hub in 2014. In one experiment, soybeans were no-‐till planted into mulch from a winter cereal cover crop that was mechanically terminated with a roller-‐crimper. This cover crop-‐based no-‐till system is designed for organic production and has been shown to be a viable practice in New York State. Five soybean planting densities were compared and we measured crop population, weed suppression, and crop yield. An economic analysis of the data shows that profitability was maximized at 315,000 seeds/acre, which is more than double the recommended seeding rate in conventional soybean production. This information contributes to an on-‐going effort to define management recommendations for organic no-‐till soybean production. The second practice that we tested in a separate experiment involved interseeding cover crops into heritage corn cv. ‘Bloody Butcher’. Late cover crop establishment after grain harvest in the fall often leads to poor growth and few benefits. Here we interseeded the cover crop in mid-‐summer using a new machine that drills the seed between rows of corn. Although research on this practice in other areas has shown that it can be successful, the cover crops that were interseeded at the Farm Hub performed poorly. High soil moisture during cover crop establishment, competition from weeds, and herbivory from slugs and arthropods might have contributed to the poor cover crop performance at this site. More research is needed on cover crop interseeding to identify the factors that limit cover crop growth and to determine the effects on host corn crop performance. Information generated in this project was disseminated to farmers at two field days and through a factsheet distributed at the NOFA-‐NY winter conference. Background Information
Weed and soil fertility management are among the largest hurdles to organic grain crop production and are consistently ranked as top research priorities by organic farmers. Many organic farmers rely on tillage and cultivation to suppress weeds, but this can degrade soil health and leave soil susceptible to erosion. Integrating legume forage crops, such as alfalfa, into crop rotations has long been recognized for providing pest suppression and soil fertility benefits. However, some farmers transitioning to organic grain crop production cannot use forage crops because they lack equipment and markets for these crops. Cover crops are tools that can help farmers overcome challenges when transitioning to organic production. Cover crops can replace external inputs such as nitrogen fertilizer and herbicides and they can enhance agroecosystem performance and overall productivity by increasing supporting and regulating ecosystem services (i.e. benefits that humans obtain from ecosystems) such as pollination and biological pest control1. Not only can cover crops offset the negative impacts of tillage by increasing soil organic matter, they can also enable organic farmers to reduce tillage by providing weed suppressive mulches. However, more research is needed to develop new cover crop management recommendations for organic farmers.
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Cover crop-‐based, organic rotational no-‐till management relies on mulch from cover crops instead of cultivation to suppress weeds and is a promising approach to increasing ecosystem services in organic cropping systems. Unlike mechanical weed management, using cover crops as mulch moderates soil temperature, reduces erosion, conserves soil moisture, and creates a favorable environment for beneficial insects. Farmers are interested in cover crop-‐based, organic rotational no-‐till because it can save time and energy. For example, compared to traditional tillage-‐based production methods in an organic corn-‐soybean-‐wheat rotation, rotational no-‐till requires 27% less diesel fuel and 31% less labor2. Our previous research also shows that this method of reducing tillage can produce corn and soybean yields that are comparable to traditional tillage-‐based organic production. Despite the myriad of services that cover crops provide, the relatively small window of opportunity for cover crop seeding after corn and soybean harvest and the associated labor, fuel, and seed expenses can limit cover crop utilization. Whereas labor, fuel, and seed input costs could be justified if the benefits of cover crops outweigh them, the short window of opportunity for establishment after summer crops are harvested is a serious limitation to achieving cover crop benefits3. In a recent survey of over 1,200 corn and soybean farmers in Iowa, 61% agreed or strongly agreed with the statement "There is rarely enough time between harvest and winter to justify the use of cover crops"4. In a different survey, 64% of US farmers surveyed (n = 812) said they do not use cover crops because there is “not enough time to get a cover crop established with harvest challenges”5. Removing barriers to cover crop use and increasing cover crop performance will benefit organic growers and lead to greater adoption of organic agriculture. Results from an increasing body of literature show that early establishment of winter annual cover crops is critical for maximizing cover crop growth, nutrient scavenging, biological nitrogen fixation, weed suppression, and soil erosion control. Cover crop establishment timing is an important factor in nutrient management policy. For example, the Maryland Department of Agriculture provides a greater cost share to farmers who seed cover crops early in the fall and terminate them late in the spring6. Another downside to late seeding in the fall is that cover crop selection is limited to grasses because many legume cover crops will not survive winter or provide adequate benefits when seeded late. One potential solution to overcoming cover crop establishment timing problems is to establish winter cover crops prior to harvesting crops in the fall. Previous research in New York demonstrated that several cover crop species, including white clover, red clover, barrel medic, alfalfa, annual ryegrass, and creeping red fescue, could be successfully established in soybean prior to harvest without reducing yields or interfering with soybean combining7. More recently, researchers in Maryland compared winter cereal cover crops established with a grain drill to cover crops established by broadcast seeding using a spinner-‐type fertilizer spreader. They also included treatments with and without soil incorporation by disking. Cover crop establishment with broadcast seeding was highly dependent on soil moisture, and in all cases soil incorporation improved establishment of broadcasted cover crops. They concluded that broadcast seeding cover crops into soybean prior to leaf drop was effective and could improve soil and water conservation8.
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Project Objectives
Our goal was to test and demonstrate advanced cover cropping practices that improve soil health and weed suppression in organic grain crop production. Project objectives included: 1. Conduct a field experiment on cover crop-‐based, organic no-‐till tofu soybean
production and quantify the effects of soybean seeding rates on a series of performance indicators, including weed suppression and soybean yield.
2. Conduct a field experiment on cover crop interseeding into heritage corn and evaluate the effects of different cover crops and interseeding methods (broadcast vs. drill interseeding) on cover crop establishment, weed suppression, cover crop biomass production, and nitrogen availability in the following spring.
3. Disseminate new information from field experiments and empower farmers in the region with practical knowledge to assist them with producing organic food grain crops.
No-‐Till Tofu Soybean Seeding Rates (Objective 1)
Materials and Methods This experiment was focused on no-‐till planting organic tofu soybeans into rolled-‐crimped winter cereal cover crops. Our previous research has shown that seeding recommendations based on conventional soybean production are inappropriate for organic soybean production and that organic farmers can realize greater yields and profits with higher seeding rates. However, at extremely high rates, soybean plants can lodge (i.e. fall over) and make harvesting difficult, especially when no-‐till planted into rolled-‐crimped cover crops. To better understand these tradeoffs, we compared five different soybean seeding rates ranging from 80,000 to 370,000 seeds/a. We used an early maturing clear hilum tofu soybean variety (IA2053, group 2.1 relative maturity). Results and Discussion
A local commercial agribusiness established the cover crop in the fall of 2013 in field ‘Paul 9’ at the Farm Hub. Although the cover crop was supposed to be a pure stand of triticale, it was comprised of approximately 50% cereal rye (Photograph 1). Prior to no-‐till planting the soybean seed, we mechanically terminated the cover crop with a 10-‐ft wide roller-‐crimper (I & J Manufacturing) on June 10, 2014. This provided a uniform layer of mulch (Photograph 2). Cover crop termination was near complete, but a few plants rebounded and remained upright after rolling. This was likely due to uneven field micro-‐topography resulting from soil disking prior to seeding the cover crop the previous fall. We rolled the cover crop parallel to ridges in the soil, which allowed some of the cover crop to escape the full down-‐force pressure of the roller-‐crimper. Rolling perpendicular to the ridges would likely result in a more complete termination of the cover crop, but this might also make for an uncomfortable ride for the operator. We used an 8-‐row John Deere no-‐till planter to plant the soybeans in this experiment (Photograph 3). This planter was equipped with the capacity to adjust planting rates in the cab, which expedited the planting process.
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Photograph 1. Winter cereal cover crop consisting of triticale (shorter) and cereal rye (taller) was terminated with a roller-‐crimper. Soybean establishment was fairly good, despite somewhat poor seed furrow closure (Photographs 4 and 5). However, soybean establishment decreased at the higher planting rates (Figure 1). Weed suppression increased with soybean planting density and plots planted at the highest rate were weed-‐free (Figure 2). This is congruent with our previous research and shows that increasing planting rates increases shading by the crop and is an effective cultural weed management practice. Weeds decreased soybean yield with the lowest yield observed in the plot with the greatest weed biomass (Figure 3). Interestingly, we did not observe soybean lodging in this experiment (Photograph 6). Previous research showed that soybean lodging could be exacerbated at the high planting rates. Even at the 370,000 seeds/acre rate, soybean plants did not lodge. Non-‐linear regression was used to model the effect of planting density on soybean yield (Figure 4). Soybean yields were maximized at the 315,000 seeds/acre planting rate and decreased slightly at the highest planting rate. We conducted a partial budget analysis to determine the economic optimum using the actual soybean seed cost from our supplier (Lakeview Organic Grains) and 2014 USDA AMS market value for food grade soybean (Table 1). Our results show that profitability was maximized at the 315,000 seeds/a planting rate, which is more than double the recommended planting rate for conventional soybean production. This is likely due to the enhanced weed suppression at higher soybean planting rates, which is typically not considered with conventional herbicide resistant soybean production. Collectively, the enhanced weed suppression, slight yield advantage, and high market value point to advantages with high soybean planting rates. Our results indicate that organic farmers using the rolled cover crop system should plant soybeans close to 300,000 seeds/acre to maximize weed suppression, soybean yield, and profitability.
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Photograph 2. Flattened cover crop after rolling just prior to no-‐till planting soybean.
Photograph 3. No-‐till planting soybean into the cover crop mulch.
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Photograph 4. The no-‐till planter was equipped with spike-‐tooth closing wheels and residue managers in front of the coulter. However, the field was planted with the residue managers in the raised position to maintain mulch around the seed furrow.
Photograph 5. Under the high soil moisture conditions, the spike-‐tooth closing wheels indented the soil, but did not facilitate seed furrow closure.
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Figure 1. Actual soybean population at harvest across target soybean planting rates. Complete (100%) emergence is shown as a reference with the dotted line.
Photograph 6. Soybean plants standing tall in field ‘Paul 9’ on August 29, 2014.
75,000
150,000
225,000
300,000
375,000
75,000 150,000 225,000 300,000 375,000Soybean planting rate (seed a−1)
Soyb
ean
popu
latio
n (p
lant
s a−
1 )
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Figure 2. Weed biomass across relativized soybean populations (0 = 80,000 seeds/acre).
Figure 3. Soybean yield loss as a function of weed biomass.
0
1,000
2,000
3,000
0 1 2 3 4Relativized soybean population
Wee
d bi
omas
s (lb
a−1
)
20
30
40
50
60
0 1,000 2,000 3,000Weed biomass (lb a−1)
Soyb
ean
yiel
d (b
u a−
1 )
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Figure 4. Soybean yield as a function of soybean planting rate.
Table 1. Partial budget analysis of the five different soybean planting rates using soybean yields, seed costs, and 2014 market value.
Soybean planting rate (seed a-‐1)
Soybean seed cost1 ($ a-‐1)
Average soybean yield
(bu a-‐1)
2014 soybean market value2
($ bu-‐1)
Partial profit ($ a-‐1)
80,000 $25 31.1 $29 $876
170,000 $53 40.9 $29 $1,132
250,000 $79 45.0 $29 $1,225
315,000 $99 50.4 $29 $1,364
370,000 $116 45.4 $29 $1,199
1Seed costs are from actual seed purchased from Lakeview Organic Grain. http://www.lakevieworganicgrain.com/info_docs/seed_spring_prices1.html 2Food grade soybean price from USDA. http://www.ams.usda.gov/mnreports/lsbnof.pdf
20
30
40
50
60
75,000 150,000 225,000 300,000 375,000Soybean planting rate (seed a−1)
Soyb
ean
yiel
d (b
u a−
1 )
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Cover Crop Interseeding into Heritage Corn (Objective 2)
Materials and Methods
We tested the effects of cover crop interseeding into heritage corn (cv. ‘Bloody Butcher’) using a split-‐plot randomized complete block design. The five main plot treatments were focused on cover crop species and included:
1. Untreated control – no cover crop 2. Annual Ryegrass (20 lb/a) 3. Annual Ryegrass (10 lb/a) and Forage Radish (5 lb/a) 4. Red Clover (10 lb/a), Crimson Clover (20 lb/a), and Hairy Vetch (15 lb/a) 5. Annual Ryegrass (10 lb/a), Red Clover (5 lb/a), Crimson Clover (10 lb/a), and Hairy
Vetch (7.5 lb/a) The split plot treatments compared drill interseeding with the InterSeeder to aerial broadcasting interseeding with an EarthWay spreader. Legume cover crop seed was inoculated with an appropriate inoculant prior to seeding. Corn cv. ‘Bloody Butcher’ was planted into tilled soil on May 12, 2014. We transported the InterSeeder from Cornell University to the Farm Hub on June 30, 2014. This was later than ideal as the corn was rather tall and had a completely closed canopy (Photographs 7 and 8). Rain and wet soil conditions prevented us from interseeding earlier.
Cover crop establishment was assessed on July 29, 2014 using a visual rating of 0 to 10 where 0 = no cover crop and 10 = excellent stand (complete ground cover). Corn was harvested on November 19, 2014 and yield was quantified with a Brent weigh wagon that was transported from Cornell University. This was done to evaluate whether or not the host corn crop was affected by the cover crop interseeding either through physical damage or through competition from the cover crop for limited resources (e.g. nutrients or water).
Results and Discussion
Average corn population ranged from 19,000 plants/acre in the control treatment to 21,500 plants/acre in the annual ryegrass treatment. The lack of variability in corn population and the fact that the lowest population was observed in the control treatment where the drill interseeder was not used indicates that drill interseeding did not reduce corn populations.
A visual assessment of cover crop establishment and performance indicated that all cover crops successfully emerged (Photograph 9). However, by this time very little light was penetrating the canopy and the cover crops were somewhat spindly. Visual ratings were used to compare aerial broadcast interseeding to drill interseeding. Average cover crop stands ranged from 2.5 in the Annual Ryegrass and Forage Radish mixture to 5.75 in the Annual Ryegrass and Legume mixture. Surprisingly, no difference between aerial broadcast interseeding and drill interseeding was observed (Table 2). This is an interesting finding when the cost of the different approaches is considered. However, it is important to note that broadcast interseeding might have performed better than usual because of the wet conditions after seeding. More research is needed across a larger range of environmental conditions to better understand the effect of soil moisture on cover crop establishment.
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Photograph 7. Cover crops were interseeded on June 30, 2014. Chris Pelzer is shown above operating the cover crop InterSeeder.
Photograph 8. We compared drill interseeding to broadcast interseeding, which was simulated by hand spreading. Brian Caldwell is shown above spreading seed with a hand-‐held EarthWay spinner spreader.
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Photograph 9. Drill interseeded cover crops across treatments on July 29, 2014.
Table 2. Results from analysis of variance of visual rating data showing no effect of cover crop treatment or interseeding method.
Effect Num DF Den DF F value P value Cover Crop Treatment 3 9 1.17 0.3753 Interseeding Method 1 12 0.04 0.8483 Cover Crop x Method 3 12 0.57 0.6434
Average corn yield ranged from 82-‐92 bu/a at 15.5% moisture across treatments. Analysis of variance showed significant treatment effects on corn yield (P = 0.04). Corn yield in the Control and Legume treatments was significantly greater than in the Annual Ryegrass and Annual Ryegrass and Forage Radish treatments. The Annual Ryegrass and Legume treatment was not significantly different than any of the other treatments. It is interesting that the two treatments that were not significantly different from the control contained legumes. Although this could indicate that the corn was nitrogen limited and that the cover crop competed with the corn for nitrogen, the fact that the cover crops were interseeded rather late after the critical weed-‐free period in corn suggests that other factors are responsible for the difference. More research is needed to further explore competition between interseeded cover crops and host cash crops.
Annual&Ryegrass&(10&lb/a)&and&Forage&Radish&(5&lb/a)&
Red&Clover&(10&lb/a),&Crimson&Clover&(20&lb/a),&and&Hairy&Vetch&(15&lb/a)&
Annual&Ryegrass&(20&lb/a)&
Annual&Ryegrass&(10&lb/a),&Red&Clover&(5&lb/a),&&&Crimson&Clover&(10&lb/a),&and&Hairy&Vetch&(7.5&lb/a)&
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Figure 5. Visual rating of cover crop performance ranging from 0 to 10, where 0 represents no cover crop present and 10 represents complete ground cover.
Figure 6. Corn yield across cover crop treatments. Similar letters above bars indicate no significant difference (P > 0.05).
0 1 2 3 4 5 6 7 8
Annual ryegrass
Annual ryegrass and
radish
Legumes Annual ryegrass and legumes
Visual rating (0-‐10)
Drill interseeded Broadcast
0 10 20 30 40 50 60 70 80 90 100
Control Annual ryegrass
Annual ryegrass and radish
Legumes Annual ryegrass and
legumes
Corn Yield (bu/a) at 15.5%
moisture A A
B B AB
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The cornfield was disked and the experiment was terminated on December 4, 2014, and thus no spring cover crop biomass was collected. On December 5, 2014, John Gill reported the following: “We took a look and could not find hardly any thing but dead weeds and stalks. If there was a 10% stand of cover crop, that was the most. The only place we found any was along the outside southern most rows.” Despite the strong start with these cover crops, potential benefits were limited with poor fall growth.
Outreach Activities
Information from this project was disseminated to farmers and other stakeholders through a variety of outlets. A mid-‐project report titled ‘Organic No-‐till Tofu Soybean Production at the Hudson Valley Farm Hub’ was created and distributed at the 2015 Northeast Organic Farming Association of New York (NOFA-‐NY) Winter Meeting in Saratoga Springs, NY. On July 18, 2015 we hosted a twilight tour of our research plots at the Musgrave Research Farm in Aurora, NY. This event was titled ‘Ready To Roll? New Field Research On Organic No-‐Till Soybean With Rolled-‐Crimped Cover Crops’ and was co-‐sponsored by NOFA-‐NY. Approximately 30 people attended, including several local conventional farmers who were considering the transition to organic production. Jeff Liebert presented on his research on the cover crop-‐based, organic rotational no-‐till system, including his soybean planting rate experiment at the Farm Hub. He reported on his economic analysis of different soybean planting rates and emphasized that profitability was optimized at approximately double the recommended planting rate for conventional soybeans. A summary of the twilight tour, the handout that was distributed, and photographs from the tour are posted on-‐line at: https://scslabcu.wordpress.com/2015/07/08/twilight-‐tour-‐at-‐musgrave-‐research-‐farm/. On July 2, 2015, Brian Caldwell presented at the ‘3rd Annual Small Grains Field Day’ at the Farm Hub. Given the focus on small grains at this event, Brian Caldwell focused his presentation on organic cropping systems, crop rotation, and the use of cover crops. Information from this project will also be presented at several upcoming farmer-‐focused field days and workshops.
References: 1. Bommarco, R., Kleijn, D. & Potts, S. G. Ecological intensification: harnessing ecosystem services for food security.
Trends Ecol. Evol. 28, 230–238 (2013). 2. Mirsky, S. B. et al. Conservation tillage issues: Cover crop-‐based organic rotational no-‐till grain production in the mid-‐
Atlantic region, USA. Renew. Agric. Food Syst. 27, 31–40 (2012). 3. Baker, J. M. & Griffis, T. J. Evaluating the potential use of winter cover crops in corn–soybean systems for sustainable
co-‐production of food and fuel. Agric. For. Meteorol. 149, 2120–2132 (2009). 4. PMR 2012. http://www.mccc.msu.edu/states/Iowa/2011_IA_Attitudes_toward_CC.pdf 5. CTIC 2010.
http://www.ctic.org/media/pdf/Cover%20Crops/CTIC_HGBF_CroppingDecisionsSurvey_CoverCropSummary.pdf 6. MDA 2012. http://mda.maryland.gov/resource_conservation/Pages/cover_crop.aspx 7. Hively, W. D. & Cox, W. J. Interseeding Cover Crops into Soybean and Subsequent Corn Yields. Agron. J. 93, 308 (2001). 8. Fisher, K. A., Momen, B. & Kratochvil, R. J. Is Broadcasting Seed an Effective Winter Cover Crop Planting Method? Agron.
J. 103, 472 (2011).
For more information about this project contact Matthew Ryan at [email protected] (Lead Investigator), Jeff Liebert [email protected] (Soybean Experiment Coordinator), or Chris Pelzer [email protected] (Cover Crop Interseeding Experiment Coordinator) or visit our website at https://scslabcu.wordpress.com/.
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