Newsletter – Page 5 – Champlain Valley Crop, Soil & Pasture

Regenerative Agriculture and the Carbon Conversation

UVM Extension Agronomy Outreach Professional (Grazing Specialist)

In March 2016 a concerning milestone was reached: global levels of atmospheric carbon dioxide passed 400 parts per million (ppm). For reference, 350 ppm is recognized as the level which is needed for a healthy functioning planet.

Carbon dioxide is a heat-trapping gas, which is released through human activities such as deforestation and burning fossil fuels, along with natural processes such as respiration and volcanic eruptions. Its increasing levels is one major driver of global climate change.

In November, Architect William McDonough, who specializes in sustainable development, published an article titled, “Carbon is Not the Enemy” in the journal Nature. In it he suggests we can work with carbon in all its forms, to keep it in the right place. Climate change, he says, is “the result of breakdowns in the carbon cycle caused by us, it is a design failure. Anthropogenic greenhouse gases in the atmosphere make airborne carbon a material in the wrong place, at the wrong dose and for the wrong duration.”

A healthy carbon cycle supports life, rather than endangering it. McDonough writes that the way to work with the carbon cycle to preserve and enhance the benefits it provides starts with the soil. A healthy soil can sequester carbon, converting it to a stable form which improves its fertility and ability to hold water.

Dr. Christine Jones, an Australian soil ecologist who was highlighted in the book Cows Save the Planet, describes this process. Plants convert carbon dioxide into sugars or “liquid carbon” which is used for plant growth and is exuded by the roots to feed soil microbes. The plants obtain minerals and trace elements otherwise unavailable to them and in turn, the microbes use the sugars to create stable carbon, including humus. Dr. Jones states that much of the world’s grazing land is losing carbon due to overgrazing practices. However, she writes about the potential to sequester carbon and reduce atmospheric CO₂ levels through management changes to improve soil health and activate the “liquid carbon” pathways. There is an enormous potential for the world’s grasslands to capture and sequester carbon and perhaps lower atmospheric carbon dioxide levels.

In a 2014 paper titled “Regenerative Organic Agriculture and Climate Change”, The Rodale Institute states that farming practices that maximize carbon fixation and minimize carbon loss have the potential to sequester more than 100% of current annual carbon dioxide emissions. However, to achieve this, a holistic systems approach to agriculture is needed worldwide that builds soil health by adopting cover crops, crop rotations, and conservation tillage practices.

Currently, The Savory Institute, co-founded by Holistic Management author and educator Allan Savory, is working to promote the importance of livestock in carbon sequestration and bring that message to the consumers. Well-managed pasture, acting as a giant solar panel, captures solar energy, grows dense stands of grasses, keeps soil protected, sequesters carbon and turns this solar energy into animal products. The institute will unveil a “Land to Market” program early in 2017 with a third party seal on qualifying products to indicate that sourcing is regenerative on the land on which it is produced.

Rodale describes regenerative agriculture as “beyond sustainable” – a system built on improving resources, through continual on-farm innovation for environmental, economic and social wellbeing. It is a model we will no doubt be hearing a lot more of as it may prove integral to climate stabilization solutions.

Sources and Additional Reading:

‘Carbon is Not The Enemy’. William McDonough. Nature. November 14, 2016. http://www.nature.com/news/carbon-is-not-the-enemy-1.20976?WT.mc_id=TWT_NatureNews

Cows Save the Planet. Judith D. Schwartz. Chelsea Green Publishing. 2013.

‘Regenerative Organic Agriculture and Climate Change’. Rodale Institute. 2014. http://rodaleinstitute.org/assets/WhitePaper.pdf

‘Meat, the unlikely climate hero?’. Bill Giebler. New Hope Network. November 3, 2016. http://www.newhope.com/news/meat-unlikely-climate-hero

Have a grazing question? Contact Cheryl [cheryl.cesario@uvm.edu, 802-388-4969 ext. 346]

Mustard Cover Crops Offer Benefits Beyond Soil Health

By Rico Balzano

UVM Ext. Agronomy Outreach Professional

There is growing consensus that cover crops have many environmental and agronomic benefits including reducing soil erosion, adding valuable organic matter, and improving overall soil health. But how do cover crops fit into a weed control program? And how may they effect other soil-borne pests and diseases?

mustad-cover-crop-ready-for-termination-and-incorporation — Mustard cover crop ready for termination and incorporation

In 2015, I received a SARE farmer grant to explore the use of mustard cover crops to help control plant parasitic nematodes*, weeds, and soil-borne diseases. Varieties of two species of mustard (Sinapis alba and Brassica juncea) have been identified as producing chemical compounds known as glucosinolates that have been shown to reduce fungus and nematodes populations when mowed and incorporated into the soil. This process is known as biofumigation.

Six varieties of mustard were trialed to test glucosinolate production and overall biomass yield. The yields were measured by weighing samples in the field, and glucosinolates were measured by a lab at the University of Idaho. The varieties were: Kodiak (Brassica juncea), Pacific Gold (Brassica juncea), Ida Gold (Sinapis alba), Caliente 119 (S.alba and B. juncea blend), Caliente 199 (S.alba and B. juncea blend), and Nemat (Eruca sativa– also a Brassica, bred as a nematode trap crop). They were planted in the spring of 2015 and allowed to grow for 60 days before incorporation and measurements were taken. It was found that ‘Caliente 199’ had the highest biomass yield and highest levels of the glucosinolate sinigrin, a volatile compound that has been shown to have anti-fungal and anti-nematode properties. Interestingly, ‘Ida Gold’ contained another gluscosinolate, sinalbin. This non-volatile compound has shown the ability to inhibit weed seed germination. Unlike Although measurements were not taken, it was observed there was less overall weed pressure in the ‘Ida Gold’ plots. This is similar to observations in trials of ’tillage radish’, another Brassica species. It was not determined whether weed suppression was a result of biofumigation or a dense cover crop outcompeting weeds. Planting rate (density) in other cover crops such as winter rye and oats has been shown to effectively suppress weeds. Further study is needed to determine how planting rates of mustards and other Brassica species effect glucosinolate production, disease suppression, and weed control.

As with any biological control, results can be variable. In trials in Idaho, higher soil moisture improved fungus and nematode suppression, while increasing weed pressure. It is necessary to macerate and incorporate the mustard plants for the glucosinolates to be effective. This can be accomplished by mowing and disking in the plants. For fall planted mustards and Brassicas, freezing and thawing may effectively macerate and release the glucosinolate sinalbin, potentially explaining weed suppression the following spring. Further study is needed to determine how these bio-chemicals and cover crops perform under different management.

*Not all nematodes are detrimental. Many play an important role in soil ecology.

Questions about using mustard cover crops? Contact Rico Balzano [802-388-4969 ext. 338, rico.balzano@uvm.edu]

2016 Fall Newsletter Introduction

A Year with the Champlain Valley Crop, Soil & Pasture Team

By Jeff Carter, UVM Ext. Agronomy Specialist

Champlain Valley Crop, Soil & Pasture Team Leader

Farmers and UVM Ext. Professionals discussing new no-till corn at an early summer crop patrol.

This has been a busy year for our Extension team in Middlebury. I prepared a summary for my boss, and during this past year we offered 72 workshops, conferences, classes and field day events and tallied 8,143 “educational contacts” who came to our programs. Many farmers and ag business members came to more than one event. We also provided 1,873 individual consultations this year for one-on-one education and production technical assistance. I hope you were able to be there. We have several new projects starting this fall and look forward to many more farm demonstrations with new cover crop mixes planted, no-till corn strategies, calcium sulfate (gypsum) and other soil health amendments, reducing compaction in clay soil, actual farm crop budgets and whole-farm mass nutrient balances. This winter will be just as busy with meetings and classes for no-till corn, cover crops and soil health, pasture and grazing, manure applicator training, nutrient management plans, updates on farm environmental laws, and regular meetings of the Champlain Valley Farmer Coalition.

New RAP Law Comes Into Effect this Fall

The rules have changed again for Vermont farmers this fall with the new RAP laws (Required Agriculture Practices) going into effect before the snow flies. Once these rules clear the last legislative hurdle, this will be a dramatic change to meet the demands for cleaner water for the future of Vermont. Not so big news if you have been following the progression of increasing restrictions on how soil and farm nutrients will be kept on the farm and not lost to our lakes and streams. All farmers need to know how this will affect them and the Agency website has all the latest news regarding these new rules for farmers: http://agriculture.vermont.gov/water-quality/regulations/rap

Have a question for Jeff? He can be reached at 802-388-4969 ext. 332 or jeff.carter@uvm.edu

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Stay updated on our events via our webpage, or via Facebook

Our team work is funded through multiple grants and could not be accomplished without our supporters and funders.

Crop Insurance Update

By Jake Jacobs, UVM Crop Insurance Education Coordinator

Dept of Community Development and Applied Economics

According to the 2012 Census of Agriculture, two fifths of all land in the United States is farmland, which equates to 915 million acres and 2.1 million farms and ranches.

Of the 915 million acres of land in farms in 2012, 45.4 percent was permanent pasture, 42.6 percent was cropland, and 8.4 percent was woodland. The remaining 3.6 percent was land in farmsteads, buildings, livestock facilities, etc. Although the amount of cropland overall was down 4 percent, the amount of cropland harvested was nearly 2 percent more in 2012 than 2007. (www.agcensus.usda.gov)

There are 389.7 million acres of cropland in the United States. Cropland includes areas used for the production of adapted crops for harvest. Two subcategories of cropland are recognized: cultivated and non-cultivated. Cultivated cropland comprises land in row crops or close-grown crops and also other cultivated cropland, for example, hay land or pastureland that is in a rotation with row or close-grown crops. Non-cultivated cropland includes permanent hay land and horticultural cropland.

Corn drought; a reason to get crop insurance. — Corn drought: one of the many reasons to get crop insurance.

Cover Crops – It’s that time of the year to think about cover crops. Cover crops include grasses, legumes and forbs for seasonal cover and other conservation purposes. Cover crops are primarily used for erosion control, soil health improvement, and water quality improvement. A cover crop managed and terminated according to these guidelines is not considered a “crop” for crop insurance purposes. The cover crop may be terminated by natural causes such as frost, or intentionally terminated through chemical application, crimping, rolling, tillage, or cutting. Cover crops may be grazed or harvested as hay or silage, unless prohibited by RMA crop insurance policy provisions. Cover crops cannot be harvested for grain or seed. If you have questions about crop insurance coverage for your cover crops, contact your insurance agent. To find an agent licensed by USDA in Vermont, go to http://www.rma.usda.gov/tools/agent.html.

Dairy MPP – The registration period for MPP-Dairy coverage for the year 2017 began July 1, 2016. In an effort to allow dairy producers to make well informed coverage election selections suitable to their operation’s needs, the registration and coverage election deadline has been extended to December 16, 2016. Contact your local FSA office for more information or to register.

For more information about crop insurance contact Jake Jacobs [802-656-7356 or jake.jacobs@uvm.edu]

What’s Your Watershed

A Look at Lake Champlain & McKenzie Brook

By Kristin Williams, UVM Ext. Agronomy Outreach Professional

Drainage basin map with sub basins — Public Domain, via Wikimedia Commons

With the ever present focus on water quality in the state of Vermont, now is a good time to know where you sit on a map. Watersheds are not always an intuitive concept, particularly in Vermont where things can drain in unpredictable ways. A watershed is an area of land where the brooks, streams, and rivers all drain into a common location such as a lake or larger river. You can think of watersheds as a hierarchy. A drainage basin is the larger watershed unit for which all waters drain into a common large water body, such as Lake Champlain. Watersheds and sub-watersheds are a division of basins into smaller units. The entire lake is subdivided into sections for the management of water quality. One such segment is South Lake, which includes the McKenzie Brook watershed.

There have been efforts in the state to focus on these smaller watershed and sub-watershed units as a way to target efforts and resources in reducing phosphorus loading on Lake Champlain. Part of this effort is a funding focus on the part of NRCS. This approach is being piloted in an attempt to demonstrate whether more success can be gained from a geographic strategy. It should be noted that the “targets” are areas where additional money and time is being allotted, with the possibility that those “targets” will move as successes are reached. This is the first year of this approach.

The Champlain Valley Crop, Soil and Pasture Team has been participating in this focused effort. The watershed currently targeted that falls within our farm community is McKenzie Brook. Other watersheds currently in NRCS focus are Pike River, Rock River, and St. Albans Bay. McKenzie Brook proper is actually in New York, but this is the name of the watershed that extends above Crown Point Bridge in the north (near DAR state park, Addison VT) to Route 73 in the south (just north of Mt. Independence state park, Orwell VT) and covers a narrow geographic region inland from the lake including Hospital Creek, Whitney Creek, Braisted Brook and the Lake Champlain Tributary.

One of our grants that recently wrapped up was assessing the status of farmer’s nutrient management plans and helping farmers who needed new or updated plans get through the process. A second grant focused on the McKenzie Brook watershed is ongoing assisting farmers in signing up and following through with NRCS EQIP contracts to implement best management practices (BMPs). Thus far, NRCS has been able to obligate $800,000 of a $1 million dollar allocated potential for targeted conservation practices in McKenzie Brook watershed.

We will continue to assist farmers in signing up and implementing practices. In addition, we are happy to help farmers try projects on small plots that may be outside the payment structure of NRCS. Collectively, we hope to quantify both NRCS and non NRCS funded practices in McKenzie Brook to demonstrate conservation success over time. We also have demonstration projects set up specifically in McKenzie Brook, and will continue to facilitate discussion over successes and agronomic realities of practices. Look for information about upcoming events on our events webpage. However, you don’t have to be in McKenzie Brook to try a new practice. We have a lot of work going on in and around Chittenden, Addison and Rutland Counties, and imagine that “targets” may eventually move to other areas within the South Lake region.

This spring we also began engaging in a unique collaborative project with Middlebury College and the Department of Environmental Conservation that we will be continuing this fall/winter and hopefully into the future. Middlebury College students in a capstone environmental studies class embarked upon a semester long group project of their choosing. This spring students mapped existing water quality data in McKenzie Brook watershed, attended some of our workshops and meetings to distribute a farmer survey about water quality and tile drainage, attempted some water quality sampling, and presented findings to farmers. This fall another group of students will continue this work on water quality and land use mapping, water sampling, and/or “ground-truthing” of water quality modeling.

One important outcome of this work this spring was the visualization of data in a digestible format. The average concentration of phosphorus at five sample sites from 2012 to 2014 taken by the DEC is depicted in the map below (click to enlarge).

McKenzie Brook map created by Middlebury College ENVS students: Emma Homans, Hilary Niles, Ben Harris and Morgan Raith. — McKenzie Brook watershed. Water sampling points correlated with average dissolved phosphorus concentrations. Data collection 2012-2014 by VT Agency of Natural Resources: cartography by Middlebury College ENVS students Emma Homans, Hilary Niles, Ben Harris and Morgan Raith.

It should be noted that concentration and loading are two different things. We do not have flow data corresponding with this map (which may explain for example why concentrations in Upper Hospital Creek are greater than that of the West Tributary of Hospital Creek). We hope continued work will include flow monitoring to capture loading rates in addition to concentrations.

Another take-away point that should be reiterated in all this discussion of the Lake is that turning off the “valve” of phosphorus from sources isn’t the same as removing the phosphorus in the Lake. It may take substantial time to see efforts realized in the Lake even if various sectors in VT come together to reduce phosphorus loading, particularly as other factors such as rainfall and temperature continue to impact algal blooms. Therefore, we are hoping to capture an increase in farming BMPs over time as we work together with farmers, and hope to see that correlate with reduced phosphorus loading in particular tributaries. We aim to demonstrate the utility of BMPs and that the farming community is actively engaged in this process. This is an ambitious goal, and success will require buy-in from farmers and dedication from parties involved.

How do we have the “watershed moment” about watersheds? Hopefully, with continued engagement on this topic we can foster a collaborative community where farmers can learn from their neighbors and technical service providers can share information among farmers about how conservation practices are making for thriving agriculture and cleaner water in their own corner of the map.

For more information on this topic:

NRCS Handout on McKenzie Brook as a Targeted Watershed

A pdf version of the Middlebury College Student’s Spring 2016 Report and Spring 2016 Presentation

The Lake Champlain Basin Program: Phosphorus Loading by Lake Segment and Phosphorus Reduction Strategies

VT Department of Conservation (DEC): Water Quality Monitoring and Restoring Lake Champlain (including VT’s New Draft of Lake Champlain Phosphorus Total Maximum Daily Load (TMDL) Proposal to EPA)

To sign up for NRCS EQIP cost-share in McKenzie Brook contact George Tucker [802-388-6748 ext 121 or george.tucker@vt.usda.gov]

For questions about signing up you can also contact our office [802-388-4969].

For questions related to the Middlebury College projects and continued water quality work contact Kristin Williams [802-388-4969 ext. 331 or kristin.williams@uvm.edu]

Successful No-Till Alfalfa on Clay Soils

By Nate Severy, Agronomy Outreach Professional

This year there were a number of farmers who no-tilled alfalfa in clay and silty soils throughout Addison County. While this was a difficult year for good alfalfa establishment due to our dry, hot weather, all of the no-till alfalfa farmers had successful stands.

Below is a summary of what these farmers did that contributed to their success:

All farms planted during a “window of opportunity”. While all farms managed their fields differently, there are generally 3 times through the year where there is a “window of opportunity” in which you can successfully plant alfalfa into your cover crop. These are: early April before green-up, mid-late May immediately after harvesting your cover crop for forage, or August after you combine and harvest grain and straw. One positive aspect about no-till seeding is that in the spring only the top inch of soil needs to be dry in order to plant, as opposed to the entire plow layer with conventional field prep. This means you can seed much earlier in the spring without the risk of turning your clay soil into moon rocks.

All farms fertilized, prepared good/level seedbeds, and planted a cover crop last fall after short-season corn silage. Cover crop planting dates ranged from early September to the beginning of October. If you are planning on harvesting your winter rye/triticale/wheat as forage, the earlier you can plant in September, the better your spring yield will be. That means you will want to make sure you plant a corn silage variety that can be harvested early enough that you have adequate time to prepare a proper seedbed. If you do not want to harvest forage from the cover crop, either plant at a lighter rate or plant a mix that has a winter cereal with a winter-kill crop like oats or radishes.

All farms planted at the proper seeding depth. For winter cereal grains, planting depth should be between 1-1 ½ inches, which means you need to plant with a grain drill. Broadcasting and lightly tilling it (followed by a roller) can work, but there is a very fine line between incorporating your seed and burying it. Broadcasting and only going over the field with rollers is not recommended. The seeding depth for alfalfa should be between ¼ to ½ an inch. Most farms used a grain drill, but it is possible to broadcast your seed if you “aggressively scratch” the field before seeding and pack it several times afterwards.

All farms planted alfalfa into a low-competition environment. Some farms planted into their cover crops in mid-April before there was much spring growth, a farmer planted his alfalfa in May after harvesting the cover crop as forage, and a few farms planted alfalfa in April, spraying and killing their cover crop immediately afterwards. You can have good alfalfa establishment in a thick cover crop/nurse crop, but you will have less first-year alfalfa yield when compared to a light cover crop/nurse crop.

Three farms successfully frost seeded 5lb/ac red clover in March into their cover crops. Frost seeding can be an effective way to introduce crops into fields. However, you need three things to happen perfectly: very small seeds, soil that will freeze-thaw, and bare ground. These cover crop fields seemed to be good candidates for frost seeding 5lb/ac red clover in March, and by August you could definitely see where we did and did not frost seed.

Planting alfalfa and other hay crops is risky no matter the year. Hopefully more farms try this method of seeding so we can learn more about the best way to establish and maintain this valuable crop.

No-till alfalfa being planted into a cover crop and corn residue

Do you have questions about this work or would like assistance with no-till alfalfa? Contact Nate [802-388-4969 ext. 348, nathaniel.severy@uvm.edu]

Grasslands Face Troubling Times

How to Restore Their Perceived Value

By Cheryl Cesario, UVM Grazing Specialist

Scott Bauer / Photo courtesy of USDA Natural Resources Conservation Service, via Wikimedia Commons

A recent study published in the scientific journal, ‘Nature’, examined the importance of species diversity in grassland ecosystems. The German-based study included dozens of researchers collecting data along various levels of the grassland food chain. The data was collected on a total of 4600 species, the most extensive ecological sampling in Europe to date. These species, they found, interact and rely on each other to provide critical grassland ‘ecosystem services’, such as food production, soil development, carbon storage, and flood and drought mitigation, among other climate regulatory functions. The study emphasizes the importance of maintaining biodiversity across all levels of the grassland food chain, which provide synergistic effects that ultimately benefit the planet and humanity as a whole.

So if grasslands play such a critical role in our planet’s health, why are they disappearing at an alarming rate? The same month the ‘Nature’ study was published, the Union of Concerned Scientists published an article about the continued reduction of grassland acres across the U.S. From 2008-2012, extensive acreage was cultivated for the first time, mostly planted to annual crops. This phenomenon was greatest in the Great Plains and western Corn Belt, where 77% of new cropland was borne from grasslands. Several crops took their place, led by corn, wheat and soybeans. These grasslands are being traded for crops that require irrigation in areas where irrigation and drinking water supplies are shrinking.

Contrast this with the ‘Nature’ study regarding the importance of grassland biodiversity and the role these ecosystems play in climate adaptation. The regions of the country with the highest loss of grasslands are also the same ones where flooding frequency has increased the most. This doesn’t seem like the best strategy for building resiliency.

There are USDA programs designed to encourage and protect grasslands, such as the Conservation Reserve Program (CRP). CRP encourages farmers to convert highly erodible cropland or other environmentally sensitive acreage to vegetative cover, such as native grasses, wildlife plantings, filter strips, or riparian buffers. Farmers receive an annual rental payment for the term of the multi-year contract. However, enrollment peaked at 36.8 million acres in 2007, dropping to 24.2 million acres by September 2015. States such as Kansas, North Dakota, Montana and Texas have seen reductions of over 1 million acres each in CRP land over the past 8 years. For scale comparison, in Vermont our CRP acres total approximately 2,800 acres, mostly in various riparian buffer, filter strip, and habitat plantings. While we don’t have large swaths of native grasslands here in Vermont, we do import large amounts of grain from the Midwest to feed cattle and other livestock, so ultimately we are part of the grassland-biodiversity-climate adaptation issue.

When commodity prices are high, acres that transition out of the program are often not re-enrolled. The trend may continue: between 2020 and 2022, 11.6 million CRP acres are scheduled to expire nationwide and it remains to be seen what the future holds for those grassland acres. With more and more discussion and interest in adaptive, resilient and regenerative agriculture, one would hope that more policies and programs may be on the horizon to encourage biodiverse grassland ecosystems that provide so many benefits.

Schuessler, Ryan. “The enormous threat to America’s last grasslands.” The Washington Post: Energy and the Environment. June 16, 2016.

Do you have questions about grazing management? Contact Cheryl Cesario [802-388-4969 ext. 346 or cheryl.cesario@uvm.edu]

Aeration Tillage

Effects of Aeration Tillage on Hay Yield and Soil Compaction

A Demonstration

By Rico Balzano

In the Champlain Valley of Vermont, Vergennes and Covington clay soils used for grass hay production are subject to soil compaction over time as equipment travels over the crop for multiple passes for maintenance and harvest operations. The Champlain Valley Crop, Soil, and Pasture Team received a Northeast SARE grant to investigate the potential benefits of regular and consistent aerator use on permanent hay fields to help alleviate compaction and maintain consistent yields over time.

Treatments

Three field sites were selected in Bridport and Addison to impose repeated aeration tillage treatments using a Gen-Till aerator, a single-axle Aerway, or a tandem-axle (T-axel) Aerway aerator tillage implement on hay fields. Data was collected in 2014, 2015 and for the first cut of 2016 at the Addison site; and 2014 and for the first cut of 2015 at the Bridport site. Treatments at the Addison site were no aeration, aerated one year (2014), and aerated two years (2014 and 2015). The 2015 growing season was unusually wet in June with over 8.5” of rain.

Hay Yield

The aeration appears to have positively affected yield in 2016 for aeration in 2014, but negatively affected yield in 2016 for aeration in both 2014 and 2015. The second year of aeration soil was saturated during the growing season. Aeration treatments had greater yield than the control in 2014 for all three cuts, but similar or lesser yield than the control in 2015 for both cuts. It is well known that clay soil is susceptible to compaction under saturated conditions, and these results are likely reflecting those conditions.

Compaction

Soil samples were collected from each treatment block in November 2015 and sent to Cornell Soil Health Test lab for analysis. Soil compaction in the treatment areas was measured using a manual soil penetrometer to record the maximum pressure (psi) required to penetrate the soil from 0 to 6 inch depth and 6 to 18 inch depth as part of the Cornell Soil Health Test field procedures.

Surprisingly, average surface compaction measurements were not significantly different as a result of the aeration treatments. Subsurface compaction showed a slight increase under aeration, though aeration tillage is not expected to change soil compaction at that depth.

Precision Agriculture

The farmer at the Addison site, Doug Gould, used the FM-750 GPS steering guidance unit that we provided to track aeration tillage activities in the field. As a result, he has purchased his own GPS guidance system to use while aerating or during fertilizer application to improve field efficiency of machinery operations.

Conclusions

The soil conditions during the time of aeration will likely have an impact on compaction and yield. If the soil is wet at the time of treatment, aeration may be less effective and even counter productive. If the soil is dry at the time of aeration, aeration may benefit compaction and yield.

Graphics

(click on a graphic to see it enlarged)

Table 1. Effects of aeration in 2014 and 2015 on 2016 first cut hay yields.

Table 2. Hay yield results comparing control and aeration in 2014 and 2015 for all hay cuts. — Table 2. Average hay yield results comparing control and aeration in 2014 and 2015 for all hay cuts.

Table 3. First cut hay yield comparison at Addison site only. — Table 3. First cut hay yield comparing control and aeration at Addison site only for both 2014 and 2015.

Table 4. First cut hay yield comparing control and aeration at Bridport site only for both 2014 and 2015.

Table 5. Comparison of aeration and control on average soil compaction in 2014 and 2015 at both sites.

Illustration of precision agriculture methods

Questions about aeration tillage can be directed to Rico [802-388-4969 ext. 338 or rico.balzano@uvm.edu]

Work for this project was funded by:

Legumes…

Getting More Out of Your Cover Crop

By Kirsten Workman

UVM Ext. Agronomy Outreach Professional

Vermont farmers are on target to plant over 20,000 acres of cover crops this year. The majority of these acres will be planted to winter rye, but there is still time (even now) to get a little more from your cover crop.

Legumes are unique because of their ability to fix nitrogen, utilize that nitrogen themselves reducing fertilizer requirements, and contribute it back to the soil for use by the following crop. Agricultural legumes are plants that are in the family Fabaceae. Most farmers are familiar with the list of legumes that comprise their forage legume species like alfalfa, clover, and trefoil, or those that are grown for grain like soybeans, peas, lentils and even peanuts. And don’t forget the vegetable legume crops like green beans and snap peas.

Legumes also have a much lower carbon to nitrogen ratio (C:N) than cereal grains, so they decompose quicker making that nitrogen more available to the subsequent crop. If you have ever plowed down (or killed) a nice stand of alfalfa and then planted corn, then you know just how beneficial a legume in your crop rotation can be. Legumes can provide over 100 pounds of nitrogen credit per acre, which is why they are often called ‘green manures’.

Rhizobium nodulation seen on pea cover crop roots — Rhizobia nodulation seen on pea cover crop roots

The legumes themselves are not responsible for nitrogen fixation, however. This happens as a result of a symbiotic relationship between the nitrogen-fixing bacteria that invade the plant root and store nitrogen in root nodules. The plant provides the bacteria with nutrients and energy, and the bacteria provide the plant with a usable form of nitrogen. These bacteria, called Rhizobia, are able to take nitrogen gas from the atmosphere (N₂) and convert it to ammonia (NH₃), which is then converted to ammonium (NH₄⁺) and nitrate (NO₃^–) which are the forms of nitrogen usable by plants. In order for good root nodulation and maximum nitrogen production, it is important to inoculate your legumes with the appropriate species of Rhizobia bacteria at planting. Some seed is available pre-inoculated, but many times you will need to apply the inoculant yourself. Whoever you get your seed from should have inoculant available as well. Beware, however, inoculants have a short shelf-life and are also species specific. Using clover inoculant on peas or vetch will not be successful.

Plant Available Nitrogen (PAN)

From D. Sullivan, Oregon State Univ. See Reference below. — Graph 1. PAN from cover crop related to date of cover crop termination. Originally from D. Sullivan, Oregon State Univ. See reference below.

The ability of your legume cover crop to supply nitrogen to your subsequent crop depends on how much biomass and when you terminate the cover crop. This plant available nitrogen (PAN) becomes available roughly 4-6 weeks after cover crop termination. Oftentimes, a cereal grain terminated at or beyond the boot stage can actually immobilize nitrogen and create a PAN deficit, making it necessary to increase fertilizer/manure nitrogen applications. This is because microbes are tying up nitrogen temporarily as they break down the carbon rich material. Conversely, a cover crop terminated too early will provide only minimal PAN. Below is a simple explanation of the differences between cereal grain and legume cover crops and the implications of when you terminate them.

Table 1 from information in the publication by D. Sullivan referenced below. — Table 1. From information in the publication by D. Sullivan referenced below.

Considerations When Planting Legume Cover Crops

Legume cover crops will need to be planted earlier than cereal grains to survive winter and maximize N production. For clovers, you’ll want them established by August 15^th in Vermont, so this limits them to being interseeded or planted after a cereal grain harvest. The winter annual legumes can be planted as late as September 1^st through 15^th, which means you can still plant them after a timely corn harvest.

If you are planting legume cover crops only to replace nitrogen, the economics may or may not pencil out. Usually in organic systems, this is a preferred practice. However, when commercial nitrogen fertilizer is $45 for 100 pounds of nitrogen and a legume cover crop could cost you $70 per acre for that same 100 pounds the nitrogen benefit may not be financially rewarding. Certified organic fertilizer, however, could run you $150 per acre, making the cover crop a wise investment. However, a legume cover crop is more than just nitrogen, and these additional benefits are harder to quantify. According to USDA this includes “yield improvements beyond those attributable to nitrogen alone. These may be due to mulching effects, soil structure improvements leading to better moisture retention and crop root development, soil biological activity and/or enhanced insect populations below and just above the soil surface.” (Clark, SARE). They are also great soil conditioners, and can provide early weed suppression.

There are many legume cover crops, but the table below gives a list of the most common ones planted in the northeast.

Table 2: Information in this table from Managing Cover Crops Profitably, A. Clark (SARE)

References:

Sullivan, D. and N. Andrews. 2012. Estimating Plant-Available Nitrogen Release from Cover Crops. Oregon State University Extension Service.

Clark, A. 2007. Managing Cover Crops Profitably. College Park, MD: SARE.

Flynn, R. and J. Idowu. 2015. Nitrogen Fixation by Legumes. New Mexico State Unviersity Extension Guide A-129.

Carbon to Nitrogen Ratios in Cropping Systems. 2011. USDA Natural Resources Conservation Service.

Other Resources:

Do you have questions about cover crops? Would you like to conduct a trial on your farm? Contact Kirsten [802-388-4969 ext. 347, kirsten.workman@uvm.edu]