Final Report for LNE11-312
Project Information
This project investigated no-till spring vegetable production after low-residue winterkilled cover crops, primarily forage radish (Raphanus sativus L.), throughout the northeast. Experiment station research at two contrasting sites in Maryland, Clarksville and Wye, during 2011-12 and 2012-13, one year of on-farm experiments in Maine, 12 small on-farm trials in Maryland, Pennsylvania, and New Jersey, and one experiment station trial in Massachusetts revealed that differences in fall cover crop performance and soil conditions lead to variable results from no-till seeding spring vegetables after forage radish. Successful no-till seeding in spring requires early fall cover crop seeding, rapid growth, and early canopy closure to ensure spring weed suppression. Additionally, soil conditions in spring must not hinder water movement, gas exchange, seed emergence, and root growth. Poorly aggregated and/or easily compacted soils appear not to support no-till seeded vegetable crop growth.
Results from Clarksville showed no-till spinach yields after forage radish as high as 17,000 lb/acre. No-till spinach yields were equal or greater than the yields in tilled seedbeds both years at Clarksville. In contrast, tilling in a radish cover crop increased spinach yield more than 60% compared to the no-till spinach at Wye, though the differences were significant only in 2013. Limited trials with lettuce and kohlrabi indicated that while emergence was equal or greater in no-till plots, maturity was delayed. In on-farm experiments in a sandy soil in Maine, no-till seeded carrots after forage radish matured at an equal rate to those in tilled seedbeds and were of higher marketability, but one farmer in Maryland with silt loam soils reported poor root development in no-till seeded carrots. Five of the collaborating farmers reported that they have incorporated the forage radish no-till system into their regular practices for spring crops including spinach, peas, beets, onions, and carrots, whereas five expressed concerns that dissuaded them from no-till seeding after forage radish, or using forage radish as a cover crop at all. These concerns include the possibility of disease or pest carry-over into other brassica cash crops, the early seeding date required for optimal forage radish performance, and the poor performance of no-till seeded crops in their soils.
During this project, we have given presentations to over 1500 individuals at over 20 meetings and field days throughout the northeast and at international meetings, had over 40,000 unique visitors to our website and blog devoted to cover crop-based reduced tillage vegetable production, had over 2700 YouTube video views, had bulletins and articles in outlets with circulation totaling over 40,000, and have had one peer-reviewed journal article published and another in review.
Introduction:
Cover crops and reduced tillage are two management techniques that can have great environmental and soil health benefits, but multiple strategies for integrating these practices into diverse farming systems are needed. This project addressed how to eliminate spring tillage and integrate cover crops in rotations that include early spring cash crops like spinach, peas, and carrots. Traditional, high-residue cover crops can be difficult to kill in spring, can keep the soil cool and wet if they are not incorporated (tilled) into the soil, and can tie up nutrients for early spring cash crops. However, most research to-date on no-till vegetable production without herbicides has relied on these high-residue cover crops, which are mechanically killed in late spring or early summer and then act as a weed-suppressing mulch. These high-residue system, while effective for later-season crops, are ill-suited to early spring vegetables, yet spring is a critical time to reduce tillage because of the high likelihood for soil compaction and erosion during this time.
This project built on previous research in agronomic systems that revealed unique characteristics of forage radish. These characteristics include: alleviation of soil compaction; near complete early spring weed suppression; and winterkill followed by rapid decomposition of surface residue in spring. This previous research has been extensively reported in the final report for SARE project LNE03-192. In contrast to high-residue no-till systems, low-residue, winterkilled, and weed-suppressing cover crops like forage radish provide the opportunity to eliminate tillage before early spring vegetables. By capturing and storing nutrients over the winter and then making them available to spring crops, this system increases nutrient cycling efficiency. It also saves time, fuel, and risk of soil degradation by eliminating spring tillage. Early fall seeding and adequate cover crop performance are essential to creating the conditions sufficient for no-till seeding vegetables in spring.
- 120 farmers growing 2,400 acres of spring-planted vegetables will use forage radish and/or other winterkilled cover crop no-till planting system for half their spring acreage. They will reduce fall/winter N leaching by 100lbs/acre (total reduction of 120,000 lbs of N) and will use 50 lbs/acre less N fertilizer (saving >$400/acre for organic growers) in spring (60,000 lbs less N fertilizer used per year). They will use no primary spring tillage and no burndown herbicide on these acres resulting in 3 tons less erosion per acre (36,000 tons less erosion) and 1,000 lbs less herbicide sprayed. On average, they will plant their crops 10 days earlier and harvest 7 days earlier than with their old system; they will save $100/acre seedbed preparation costs ($120,000 per year) and earn $500/acre ($600,000 total) more in crop sales per year.
- 12 vegetable farmers in Maryland, Pennsylvania and New Jersey will collaborate in this research by putting out replicated strips on their farms comparing forage radish no-till planting with their customary practice for early spring vegetable planting (August 2011-May 2012).
- 6 of these farmers will experiment with other winterkilled cover crops or mixtures of forage radish and other cover crops (August 2012-May 2013).
While it is impossible for us to assess the extent of adoption of this system and the savings it has incurred, we collaborated with 12 farmers in Maryland, Pennsylvania, New Jersey, and Maine who all tried no-till seeding their spring crops after forage radish. Our original targets did not include New England farmers, but because of personnel involved on this project, we were able to extend the region for research and outreach activities beyond the mid-Atlantic. The “success” rate of these trials was about 50%. Our research documented that radish increases spring soil inorganic N content, and translating this increased N into reduced fertilizer recommendations requires further documentation. Despite interest in mixtures, fewer farmers were interested in trying them and those who did had less success with weed suppression, making them unfavorable for no-till seeding without herbicides.
Cooperators
Research
Maryland Research Station Experiments
An experiment was conducted over four site years at Central Maryland Research and Education Center-Clarksville (CMREC) and WREC Research and Education Center (WREC) in 2011-12 (year 1) and 2012-13 (year 2). Both sites had been under organic management for over three years and were maintained according to organic regulations for the duration of the experiments.
Experimental Design and Treatment Structure
The treatment structure was a 2x2x2 factorial with factors of forage radish, oat, and spring seedbed preparation. The resulting cover crop treatments were: forage radish (FR), radish-oat mix (RO), oat (OAT), and no cover crop (NC), and the spring seedbed preparations, applied to all cover crop treatments, were no-till (NT) and rototilled (RT). The experimental design was a randomized complete block split-plot design with four blocks per site-year. Forage radish and oat were the main plot factors and spring seedbed preparation was the sub-plot factor.
To avoid residual effects, a new field was used at each of the two sites in the second site year, adjacent to the field used in the first site year. Baseline soil sample data for the four site years are presented Lounsbury and Weil, 2014. The WREC 1 field was in its second year of alfalfa prior to disking in July 2011. The WREC 2 field received 2.3 Mg ha-1 poultry litter (3-0.9-2.5 NPK) and 2.2 Mg ha-1 calcitic lime in July 2012. The CMREC 1 field had a sequence of winter rye and buckwheat (Fagopyrum esculentum L.) cover crops prior to tillage in July 2011 and had a history of high dairy manure compost applications. The CMREC 2 field, which did not have a history of high compost applications, received 12 Mg ha-1 (wet) finished dairy manure compost in July 2012 (1.2-0.42-1.9 NPK on a dry weight basis; C/N ratio 11.3).
Cover Crop Seeding
All fields were disked prior to initiating the experiment. Cover crops were seeded using no-till drills (John Deere, Moline, Illinois, USA at CMREC; Great Plains, Salina, Kansas, USA at WREC) with 19 cm row spacing at rates of 10 kg ha-1 (FR) and 72 kg ha-1 (OAT). The RO treatment had alternating rows of radish and oat and the seeding rate was half of the full rate for each. Main plots were 3 m wide by 23 m long. For spring tillage, a 1.5 m wide power take off rototiller was used for a single pass down the middle of the RT subplots, resulting in sub-plots in spring that were 1.5 m wide by 11 m long. Approximate depth of tillage was 10 cm. Field activity dates are presented in Table 3. At CMREC, cover crops winterkilled by February both years. At WREC 1, none of the cover crops completely winterkilled. They were mowed with single pass of a flail mower, which successfully killed the radish but resulted in approximately 10% regrowth of the oat. At WREC 2, approximately 15% of the radish in the FR and RO cover crops and approximately 5% of the oat in the RO and OAT at WREC did not winterkill; all plots were flail mowed and were completely dead by seeding time.
Cover Crop Biomass Measurement
Cover crops were harvested from two ¼ m2 quadrats from each plot in late fall prior to expected winterkill, resulting in two subsamples per plot. Weed biomass from NC plots was harvested prior to fall tillage (for dates see Table 3); tillage was performed in late fall in the NC plots to reduce weeds in spring and to simulate the common farmer practice of “winter fallow.” Subsamples of cover crops and weeds were dried in a forced-draft oven at 50-60? C until mass was constant. Each subsample was weighed and ground to < 2 mm with a Wiley mill. Equal parts of the two subsamples from each plot were further ground to
Spinach Seeding
Spinach (Spinacia oleracea L.var. Tyee from Johnny’s Selected Seeds, Winslow, Maine, USA) was seeded in spring (for dates see Lounsbury and Weil, 2014, attached) using a three-row no-till seeder (Monosem Inc, Edwardsville, Kansas, USA) with 38 cm row spacing at WREC 1 and 2 and CMREC 2. For the OAT and RO NT plots, the seeder was equipped with row cleaners, but the coulter was able to cut through the minimal FR residue without row cleaners and row cleaners were not used for FR plots. CMREC 1 was seeded by hand with four rows and 30 cm row spacing. Depth of spinach seeding was approximately 1.5 cm for all treatments. At WREC 1, NC RT was a complete crop failure because of seed corn maggots; no spinach data were collected. The same year, NC NT, RO NT and OAT NT were deemed crop failures at WREC because weeds were present at seeding and limited labor made hand weeding not feasible two weeks after seeding. None of the NT treatments is a standard farmer practice; general protocol for weed management would have called for weed control prior to planting, but this was outside the treatment structure. At WREC 2, OAT RT was not seeded because the soil was too wet to till and therefore no data were collected from that treatment.
Spinach Emergence and Yield Measurement
Spinach emergence was measured by counting emerged plants in three separate 0.5 m sections of the middle rows. Spinach harvest at CMREC 1 and WREC 1 and 2 consisted of a single harvest of whole plants to measure yield. At CMREC 2, spinach yield was measured in two successive harvests of mature leaves for all blocks and a third harvest of mature leaves was performed for a single block (only one block was included in the third harvest due to weather). At CMREC 1 and 2, 4 m of the middle row(s) was harvested. At WREC 1 and 2, 6 m of the middle row was harvested because of lower stand densities.
Other vegetable crops
Lettuce, kohlrabi, and peas were seeded into a separate experiment with the following treatments: forage radish no-till, forage radish tilled, and no cover tilled. Emergence counts were obtained for these experiments, but only lettuce yield data were collected (see results).
Soil Sampling and Analysis
Soil samples consisted of five 0-20 cm cores from each plot that were taken using a 2 cm diameter soil probe. Cores were taken from random locations in the central 5 m of each plot, except that in plots with radish, visible radish holes that changed the level of the soil surface were avoided. Soil samples were kept cool for transportation to the lab and then dried for 1-2 weeks in a forced draft oven at 50-60? C. They were then sieved to < 2 mm and gravel weight was recorded. Bulk density was calculated using the dry mass of the soil and volume of the five soil cores; a gravel correction was made when gravel was present assuming a particle density of 2.65 g cm-3. Porosity was calculated using bulk density and assumed particle density. A single extraction was performed with 5.0 g soil and 25 mL 0.01 M CaCl2, shaken at 120 rpm on a rotary shaker for 30 minutes. Samples were centrifuged for 15 minutes at 27,000 g. Nitrate-N and sulfate-S content was determined by ion chromatography with a Metrohm 850 Professional ion chromatograph fitted with a model 858 autosampler and a 150 x 4.0 mm anion separator column (Metrohm, Riverview, Florida, USA) and ammonium-N was determined with a modified indophenol blue microplate technique.
Soil Moisture and Temperature Monitoring
Decagon 5TE and GS3 combined capacitance and thermistor sensors (Decagon Devices, Pullman, Washington, USA) were installed within the middle 5 m of the cover crop plots prior to cover crop winterkill to monitor volumetric water content and temperature at 5 cm below the soil surface. A shallow hole was dug at a location chosen randomly by tossing a trowel. If the hole clearly contained a solid radish root, the sensor was inserted so as to avoid the root itself. The sensors were inserted into undisturbed soil on the side of the dug hole.
Plastic Limit
The lower plastic limit of the soil was determined using four replicates of field moist soil that was wetted evenly and repeatedly rolled into a 3 mm threat until the soil no longer held together. The gravimetric water content was determined at this point.
Weed Cover and Management
Weed ground cover was estimated by making visual assessments of percent ground cover using comparison charts adopted for use in estimating foliage cover. Percent ground cover of the whole plot was estimated twice by standing directly at either end of the plot and the two values were averaged. Weeding was performed by hand using a hand hoe (Johnny’s Selected Seeds, Winslow, Maine, USA).
Statistical analysis
Data were analyzed using a mixed model in SAS 9.2 (SAS Institute, Cary, North Carolina, USA) with block as a random factor. Data collected after spring seedbed preparation and seeding, including emergence, yield, and soil data, were analyzed as a split plot with spring seedbed preparation as the subplot factor. If a multi-way factorial ANOVA showed significant interactions (F test=0.05 or less), only simple effects were compared. Treatment means were compared using an F-protected LSD (α=0.05). Repeated measures were used to compare harvest 1 vs. harvest 2 in the case of CMREC 2.
On-farm trials in the mid-Atlantic
On-farm trials were more qualitative than quantitative in nature. We asked farmers to include replicated strips/beds of the experimental treatment (no-till after forage radish) along with their “usual” treatment prior to early spring vegetables. This was done in some cases, and in others, the whole field was planted to forage radish. In spring, we asked for qualitative feedback about weed suppression, seeding equipment performance, and crop performance, along with feedback on whether they would try this system again and what changes they would make.
Experiments in Maine and Massachusetts
An on-farm experiment was planted in Turner, ME, in a well-drained fine sandy loam soil (map unit does not match actual field data; soil series unknown). Forage radish was seeded into rototilled soil using a Monosem precision seeder with rows 10” apart and seeds placed every 2.5” on August 4, August 15, and September 1, 2013. At seeding, 40 lb/acre N in the form of mustard seed and fish meal was applied to the cover crop plots, but not to the no cover crop control treatment, which received this fertilizer in spring. There were four blocks in a randomized complete block design. In spring, blocks were split into rototilled and untilled treatments and plots into with (50 lb N as fish meal) and without spring fertilizer treatments. For the no cover crop control, this fertilizer application was in addition to the 40 lb/acre N applied in spring. Spinach (var. Tyee) and carrots (unpelleted, var. Mokum) were seeded in rows 12” apart using a Monosem precision seeder with double disk openers on April 27, 2014. Observations were made of weed pressure in the different planting dates, but no quantitative analysis was performed. Two blocks of spinach and one block of carrots were destroyed by cutworm, and no data were collected in spring. All plots were maintained with hoeing and hand weeding in late May. Successive harvests of spinach leaves occurred from two blocks on June 15 and June 26. Carrots were harvested from three blocks on July 14. Yield data are presented in attached document. Because of the loss of blocks, only descriptive data are presented.
Researchers at the University of Massachusetts were interested in trying the forage radish no-till system for spinach at the research farm in South Deerfield, MA. They seeded forage radish on three planting dates in August into a moderately well drained Winooski silt loam soil. Qualitative observations are included in the discussion.
- 1,000 vegetable farmers managing 20,000 acres of land will learn about the concept of using low residue winterkilled cover crops to facilitate no-till spring planting through extension bulletins (May 2011 and 2012).
Extension bulletins and articles were published in print and online materials throughout the Northeast with combined circulation of over 40,000 (see publications). In addition to bulletins and articles authored by our team, the concept was picked up by popular agricultural press and featured in magazines like Country Folks Magazine. We do not feel we can accurately determine the actual readership and acres of land managed, but with such a wide distribution of information, we are optimistic that we have reached at least 1,000 farmers, a portion of whom will be interested in trying this system.
- 500 farmers will attend fall and spring field days and meetings where the new cover crop systems are featured (fall 2011 and 2012 and spring 2012 and 2013) and/or will visit our website and download information on equipment modifications, no-till planting and cover crops.
Over 1500 farmers attended winter meetings and/or field days where we presented on this research (see outreach). Additionally, the website we launched in December 2013 had received over 40,000 unique visitors with over 75,000 visits as of April 23, 2015.
- 300 farmers will request additional information and/or seeds though our free seed outreach and will consider trying some version of this basic system.
At some presentations and field days, we provided seed packets for farmers. We gave out approximately 150 seed packets. We received very few requests for further information/seeds. When individual follow-up has been attempted with farmers who took seeds and shared their contact information, the response rate has been low. However, of the few responses we have received, feedback has been positive.
- 150 farmers will plant 500 acres of spring crops by the radish/winterkilled cover crop no-till method.
We are unsure of how many farmers have actually adopted these systems and of the total acreage. Measuring actual adoption is the most challenging aspect of assessing the impact of this work. We know at least five of our farmer collaborators have adopted this system and we sometimes hear of others, but it is uncommon for farmers to get in touch with us and tell us when something does (or doesn’t) work. It is especially hard to measure when farmer-to-farmer communication, the most effective form of communication, is at work and farmers learn of the practice through other farmers without any direct connection to us. We know of at least a few instances of this avenue to adoption, in particular when farms host formal or informal training programs.
- 120 of these farmers will experience significant time-saving, financial benefits and soil quality benefits from using the system.
As discussed, we are unable to assess adoption and savings accurately. Of the farmers with whom we worked closely, we have heard repeatedly that one of the biggest benefits for them is the time savings in spring. Not having to prepare the field before seeding allows them to take advantage of small weather windows to get seeds and plants in the ground. This number of farmers (120) was based on an 80% success/adoption rate of the 150 farmers whom we predicted would try this system. This success rate may be an overestimate. From our observations, not all soils are appropriate for no-till production, there are a number of ways this system can fail, and some farmers have concerns about integrating forage radish into their rotations.
Education
Presentations and webinars (reverse chronological order)
- upcoming: N. Lounsbury. Maine Organic Farmers and Gardeners Association Farmer to Farmer Conference. Northport, ME (November, 2015).
- N. Lounsbury. Winterkilled Cover Crops. University of Maryland Nutrient Management Program (webinar). 40+ nutrient management specialists. (February 12, 2015). available https://webmeeting.umd.edu/p1hiwibknyu/?launcher=false&fcsContent=true&pbMode=normal
- N. Lounsbury. No-till Spring Vegetables. Maine Agricultural Trade Show. Augusta, Maine. 100+ farmer attendees (January 13, 2015).
- N. Lounsbury. No-till vegetables: harnessing the power of cover crops. Ecological Farmers of Ontario Annual Conference. Orillia, Ontario. 60+ farmer attendees (December 6, 2014).
- N. Lounsbury. Cover crops in gardens. Montgomery County Master Gardeners 200+ gardener attendees (November 6, 2014).
- N. Lounsbury. Low-residue cover crops for organic no-till. Agronomy Society of America Annual Meeting. Long Beach, California. 60+ attendees (primarily researchers) (November 4, 2014) Available https://scisoc.confex.com/scisoc/2014am/videogateway.cgi/id/22549?recordingid=22549
- R. Weil. Cover Crops and Yield. Cover Crop Solutions Field Day. Holtwood, PA. 200+ attendees. (October 28, 2014).
- T. DuPont and D. Liker. Low-residue winterkilled cover crops for no-till spring vegetables. Northeast Organic Farmers Association (NY) Annual Meeting. Saratoga, New York (January 25, 2014).
- N. Lounsbury. Low-residue winterkilled cover crops for no-till spring vegetables. Northeast Organic Farmers Association (NJ) Winter Conference. 75+ attendees (January 25, 2014).
- N. Lounsbury Low-residue winterkilled cover crops for no-till spring vegetables and Managing nitrogen with cover crops. Long Island Ag Forum. Riverhead, NY. 75+ farmer attendees (January 16 & 17, 2014).
- R. Weil. Low-residue winterkilled cover crops for no-till spring vegetables. Future Harvest/ Chesapeake Alliance for Sustainable Agriculture Annual Meeting. College Park, Maryland. 30+ farmer attendees (January 16, 2014).
- N. Lounsbury and R. Weil. No-till spring vegetables. Maryland Organic Food and Farming Association Annual Meeting. Annapolis, Maryland. 15 farmer attendees (February 16, 2013).
- N. Lounsbury. Using forage radish as a cover crop. Harford Co., MD Mid-winter meeting. 75+ attendees (February 12, 2013).
- N. Lounsbury and R. Weil. Spring seedbed characteristics after winterkilled cover crops. Penn State Cover Crop Innovations Webinar Series. (February 4, 2013) 600+ views Available: http://extension.psu.edu/plants/sustainable/courses/cover-crop-innovations-webinar-series/webinars/spring-seedbed-characteristics-after-winter-killed-cover-crops
- N. Lounsbury. Cover crops. Better Yields through Better Soils Workshop. Baltimore, MD. 150+ attendees (February 2, 2013).
- N. Lounsbury NRCS Coastal Plain Cover Crop Field Day. Cape May, New Jersey 20 attendees (October 18, 2012).
- N. Lounsbury. Making winter cover crops work for early spring vegetable production. Mid-Atlantic Fruit and Vegetable Convention. Hershey, PA. 75+ attendees (February 2, 2012).
- R. Weil. Forage Radishes, Biodrilling, and Vegetable Crop Systems. Delaware Fruit and Vegetable Growers Association Winter Meeting. Dover, DE. 150+ farmer attendees (January 18, 2012).
- N. Lounsbury. Making winter cover crops pay for early spring vegetable production. Atlantic Coast Agricultural Trade Show. Atlantic City, NJ. 40+ attendees
(January 16, 2012).
Quotes from presentation feedback:
“It was my first time seeing the research / scientific side of farming and really appreciated the data along with practices I can easily follow on my farm.”
”But I must admit I had sort of dismissed no-till out of hand until I happened to attend Natalie's presentation... Two things really got me thinking: one was utilizing low residue cover crops like forage radish for early seeded vegetables and the other was the graphic from Weil and White of the P distribution around the radish root.”
Field Days
April 25, 2012. Cover Crops for Early Spring Vegetables and Measuring Nutrients in the Field. University of Maryland Central Maryland Research and Education Center, Clarksville, MD. Two hour twilight meeting and tour of research plots. 50 farmer and nutrient management specialist attendees.
November 14, 2013. Winterkilled Cover Crops. University of Maryland Central Maryland Research and Education Center, Clarksville, MD. Three hour workshop with presentation of research results, tour of cover crop plots, and hands-on activity to measure deep soil nitrate. 70+ farmer and nutrient management specialist attendees.
May 23, 2014 Cover crop field day and wrap up. Meeting of farmers and agricultural professionals who participated or expressed interest in this project at Gorman Produce Farm, Laurel, MD. 25 attendees.
Publications (reverse chronological order):
Lounsbury, N. and R. Weil. 2014. No-till seeded spinach after winterkilled cover crops in an organic production system. Renewable Agriculture and Food Systems. First View. (see attachment)
Lounsbury, N., R. Weil, T. DuPont, C. White, N. Shelly Gotschell, E. and A. Nordell, D. Liker. No-till, no-herbicide planting of spring vegetables using low-residue winterkilled cover crops. Small Farmers Journal Summer edition 2014 (circulation 18,000)—featured next to a photo essay by farmer Joel Miller about their experiments in New Hampshire transplanting onions into the holes created by forage radish.
DuPont, T. No-till Opportunity for Organic Growers Organic Matters- (the newsletter of Pennsylvania Certified Organic). Summer edition 2014, http://np.netpublicator.com/netpublication/n01585907 (p. 11) (800 subscribers)
Smith, L. No-till Vegetable Production by Leah Smith Passages (the newsletter of the Pennsylvania Association for Sustainable Agriculture) https://www.pasafarming.org/files/newsletter-archives/July%20August%202014.pdf/at_download/file (circulation 2500)
Lounsbury, N. NOFA-NH newsletter. http://nofanh.org/till-vegetables-start-planning-now-great-spring-crop/ (circulation 1900)
Lounsbury, N. No-till spring vegetables: let cover crops do the work for you. University of Maryland Fruit and Vegetable News https://extension.umd.edu/sites/default/files/_docs/VegetableFruitHeadlines5-3.pdf (starts p. 4) (circulation 200) (see attachment)
DuPont, Tianna. Penn State Research report http://extension.psu.edu/plants/vegetable-fruit/research-reports/no-till-no-herbicide-planting-of-spring-vegetables-using-low-residue-winter-killed-cover-crops
DuPont, Tianna. No-till no herbicide planting of spring vegetables using low-residue winterkilled cover crops. Vegetable Gazette Newsletter. June 2014, (3,000 subscribers) http://extension.psu.edu/plants/vegetable-fruit/news/2014/no-till-no-herbicide-planting-of-spring-vegetables-using-low-residue-winter-killed-cover-crops
Lounsbury, N. You can leave the rototiller in the barn next spring if you start planning now. On Pasture. http://onpasture.com/2014/06/23/you-can-leave-the-rototiller-in-the-barn-next-spring-if-you-start-planning-now/ (17,000 subscribers).
Website
In January of 2014, we launched the website and blog www.notillveggies.org. The tagline of the website is “harnessing the power of cover crops.” Recognizing that our project is only one small part in the broader picture of an increasing awareness of and focus on soil health and reduced tillage, we included detailed information about our project as well as content related to other reduced tillage projects. As of April 23, 2015, the website had received over 40,000 unique visitors. Average view time is nearly five minutes. The primary page dedicated to this project, http://notillveggies.org/cover-crops-for-no-till/low-residue-winterkilled-for-early-planting/, has been viewed over 6,000 times. A recent blog post sharing the related photos from Joel Miller in New Hampshire, who transplanted onions into the holes created by forage radish, has been viewed over 2,500 times. Some of the most popular pages and posts have been related to the broader world of cover crops and reduced tillage, but not specifically related to this project. For example, a recent blog post about reduced tillage systems in Germany has been viewed over 1,000 times. A few videos featuring seeders have been viewed over 2,700 times.
Additional Project Outcomes
Impacts of Results/Outcomes
Original performance target:
- 120 farmers growing 2,400 acres of spring-planted vegetables will use forage radish and/or other winterkilled cover crop no-till planting system for half their spring acreage. They will reduce fall/winter N leaching by 100lbs/acre (total reduction of 120,000 lbs of N) and will use 50 lbs/acre less N fertilizer (saving >$400/acre for organic growers) in spring (60,000 lbs less N fertilizer used per year). They will use no primary spring tillage and no burndown herbicide on these acres resulting in 3 tons less erosion per acre (36,000 tons less erosion) and 1,000 lbs less herbicide sprayed. On average, they will plant their crops 10 days earlier and harvest 7 days earlier than with their old system; they will save $100/acre seedbed preparation costs ($120,000 per year) and earn $500/acre ($600,000 total) more in crop sales per year.
- 12 vegetable farmers in Maryland, Pennsylvania and New Jersey will collaborate in this research by putting out replicated strips on their farms comparing forage radish no-till planting with their customary practice for early spring vegetable planting (August 2011-May 2012).
- 6 of these farmers will experiment with other winterkilled cover crops or mixtures of forage radish and other cover crops (August 2012-May 2013).
It is difficult to assess the adoption of this system on a regional scale. From the data we collected at presentations where we gave out seed packets, it seems unlikely that the average acreage of spring vegetables managed by those farmers we reached directly was 20, which was the number used to estimate this performance target. Many of the farmers at our workshops and field days manage less than 10 acres total. However, our efforts are ongoing to reach the growers who manage larger amounts of land, in particular the non-organic growers.
With respect to preventing nutrient loss, our experiment station research showed that a forage radish cover crop can capture close to 300 lb N/acre, but is more typically in the range of 150 lb/acre, though it should be noted that under some conditions there is not enough residual N to support forage radish growth and this is generally apparent in chlorotic radishes in fall. Under these conditions, N capture of less than 50 lb/acre is possible. At our field days and presentations, we were able to emphasize and even measure the depth from which N capture occurs in a forage radish cover crop. This information was of interest to farmers and nutrient management specialists in thinking about rooting depth as an important consideration in crop rotation and in thinking about the total reserves of soil nutrients instead of just the top 6-8 inches.
The fate of this N in spring is still not well understood, but our research also showed that N mineralization after a forage radish cover crop can increase surface soil (0-8”) nitrate-N in April (in MD) by more than 30 lb/acre. Further efforts are needed to determine cover crop nutrient credits in fertilizer recommendations. While the pre-sidedress nitrate test has been an effective tool to estimate N requirements in some later season vegetable crops, there is no comparable test for estimating N availability to spring vegetables based on soil N status. The role of cover crops in nutrient cycling continues to be important, especially in the Chesapeake Bay watershed, for policy makers, farmers, and environmental organizations. Although this research was conducted with vegetable production systems, we hope the insights gained with respect to N cycling will be valuable to a broader audience. In addition to N cycling, we investigated S cycling from winterkilled cover crops and found that forage radish increases surface soil (0-8”) sulfate-S concentrations by 8 lb/acre. This information has broad implications as S deficiencies become more common. Deep soil N and S may take several years to accumulate on farms, depending on soil type and management. Further research is needed to address how often a deep-rooted non-legume cover crop should be included in a rotation to optimize nutrient capture and cycling without risking inadequate nutrient availability for the cover crops themselves.
With respect to the projected earlier seeding date, our experiment station research showed that forage radish creates a dryer seedbed in spring than a high-residue cover crop like oats. This allows for earlier field work and reduces the risk of soil compaction when field work is performed while the soil is too wet. This is especially important in only moderately well-drained soils like those at the Wye research station in Maryland and the University of Massachusetts research station. At both sites, forage radish created a dryer seedbed in early spring, but neither site supported no-till spring planting because, at least in part, of poor soil aggregation and structure in these very silty, heavily tilled soils. In soils like these, a forage radish cover crop may not facilitate no-till, but the more rapid drying time may lead to earlier field work and less structural damage from tillage and traffic. In sandy soils where rapid drying in spring is not necessary, no-till seeding after a forage radish cover crop may provide the benefit of allowing soil warming while reducing soil moisture losses, as tillage can increase moisture losses from surface soil and disrupt the capillary movement of water from lower in the soil profile.
In soils where no-till seeding in spring is feasible, not having to till the soil prior to spring seeding eliminates a time-consuming step that multiple farmers expressed was critical in spring. Despite the ability in some instances to seed earlier, an earlier harvest is not always guaranteed with no-till seeding, however. For some crops, no-till seeding may delay maturity, negating an effect of earlier seeding. Results and observations were inconsistent to this effect, and further documentation is needed to determine the extent to which no-till seeding does, or does not, delay maturity of various spring crops under different soil conditions. For tilled and no-tilled lettuce and kohlrabi seeded on the same date in Maryland, no-till lettuce and kohlrabi were approximately two weeks delayed compared to their tilled counterparts; no-till spinach in Maryland showed no difference in maturity when seeded on the same date as the tilled spinach. In Maine, neither no-till spinach nor carrots showed a delay in maturity, but both had lower emergence than the tilled counterparts, resulting in lower yield.
Of the twelve farmers who had on-farm trials, half reported success with no-till planting spring vegetables after forage radish and we know at least five have turned it into a regular practice. These farmers have found that there are numerous crops harvested before optimal forage radish seeding time, which is the last two weeks of August in the mid-Atlantic, and the first week of August in New England. These include beans, garlic, onions, summer squash, and cucumbers, among others. Seeding methods used by farmers to establish forage radish include an Earthway seeder, a Planet Junior seeder, a drill, and broadcasting. Spring no-till seeding methods used with success by farmers include an Earthway, a Jang, a MaterMacc, and a Monosem seeder, although the smaller push seeders were also reported as unsuccessful by other farmers. No-till crops adopted by participating farmers include spinach, peas, beets, carrots, and (transplanted) onions. Among the farmers who did not report success on par with or exceeding their “regular” practice for early spring vegetables, the problems and concerns reported included: geese ate the foliage; concern over pest problems with another brassica in rotation (though none were actually reported); weed suppression was inadequate for no-till seeding in spring; the radish made the soil crusty; and the available equipment (an Earthway seeder) was not sufficient for no-till seeding. Among those who had success, many indicated that the biggest advantages were the time-savings in spring from not having to till the soil and the weed suppression provided by radish.
There was some interest in phacelia, but we received very little feedback on its performance. Establishment (seeding and germination) are much more difficult for phacelia. There are very few other low-residue winterkilled cover crops. Mixtures of radish and oat generally did not provide adequate weed suppression for no-till seeding in spring. Because of the need for complete weed suppression, developing cover crop mixtures to fill this cover cropping niche may be difficult. Other brassica cover crops may have some of the same advantages as forage radish, but they also raise the same concerns with pests and diseases, so further research should investigate non-brassicas to fill this niche.
- No-till lettuce and kohlrabi
- Some soils do not have good enough structure to support no-till production. These soils generally have low organic matter and low aggregate stability, and are prone to compaction.
- No-till spinach in Maryland
- Carrot and spinach yields from Maine and lettuce yields from Maryland.
- No-till carrots
Economic Analysis
We did not perform an economic analysis of this system. Any economic analysis would have to include the opportunity cost of planting a cover crop in August when the time left in the growing season is sufficient to grown one more short-season cash crop in addition to the reduced inputs afforded by this system in labor, fertilizer, and fuel and the long-term soil quality impacts of integrating cover crops into a production system.
Farmer Adoption
Follow-up with farmers is one of the most challenging aspects of measuring the impact of outreach efforts and actual adoption rates. Interest in this system has always been high during interactions with farmers, and we have interacted with many farmers. The areas that interest farmers most are generally: the biodrilling aspect of radish that alleviates soil compaction; the ability to eliminate spring tillage and save time; the weed suppression provided by radish; the nutrient cycling (N, S, P, B, Ca) provided by radish; and the more rapid drying time in spring.
The concerns farmers have expressed, and which have limited adoption, include: the desire to rotate away from brassicas for pest and disease reasons; erosion concerns from lack of residue in spring; rapid drying in spring (and potential for soil crusting); and not having ground ready for cover crops in August or wanting to grow another cash crop instead. Equipment has also been a concern for both no-till seeding and weeding, but in our observations, this has not limited adoption significantly because farmers have developed solutions to address their needs. One tactic used on small farms for making seeding and weeding easier has been to rake away residue prior to seeding. Another tactic is to transplant crops into the holes created by radish, not direct seed crops.
Some of these concerns call for further research, such as the investigation of pests and diseases associated with brassica cover crops and the short and long-term economics of cover crop use. Erosion is a serious concern with low-residue cover crops and farmers with sloped land should take this into consideration. Data show that erosion is lower with a radish cover crop than a bare, tilled field, but we and our collaborating farmers have observed erosion in spring in fields where radish was planted on sloped fields.
Farmer Quotes:
“We were worried about following forage radish with a brassica crop, but did not notice any ill effects. Some crops, like spinach, Chinese cabbage and tender greens, performed better in radish areas.”
“I wish I had planted more radish last fall. Then it (the spring planting) would just be ready to go without having to do anything.”
(after no-till seeding with an Earthway push seeder) “Everything looks great. Spinach did fantastic and there is very little weed pressure. I have yet to run the wheel hoe through. Beets did well too, I did run a wheel hoe through them. You just need to go slow and occasionally pick up the dried out radish carcass that is in the way. I did hand weed the beets but it was easy. Took me 2 hours to do 4 250 ft rows.”
(after no-till seeding with a Jang seeder) “The spacing looks beautiful. It’s really nice and even. I’m very impressed.”
Areas needing additional study
Areas needing additional study include:
- Pest and disease dynamic when brassica cover crops are included in vegetable rotations that already contain many brassica species. Specifically, cabbage maggot, flea beetle, harlequin bug, and diseases like club root.
- Development of other low-residue, winterkilled, weed-suppressive cover crops for no-till spring vegetable crops, especially not brassicas.
- Development of long-term no-till/reduced tillage rotations without herbicides, with a focus on strategies to manage perennial weeds.
- Experimentation with no-till production across soils of varying characteristics and climates within the Northeast and development of decision-making tools for farmers regarding whether tillage is necessary in a given situation.
- Greater understanding of nutrient dynamics (beyond N) after cover crops both temporally and spatially. (farmer quote: “One aspect that deserves more research is the whole area of cover crops influence on nutrient availability. eg What cover crops can we depend on to make available those anions that just seem to disappear B, Mo, SO4? With this knowledge we could then write a prescription for the cover crop mix.”)
- Long-term economic analysis of including cover crops in rotations.
- Weed management in no-till seedbed.
- Food safety with respect to grazing cover crops and/or wildlife intrusions in fall and then no-till seeding/planting in spring.