Tag: cover crops

Impact of Winter Cover Crop Termination Practices on Weeds, Soil Moisture, and Yield in No-Till Soybean

Alan Leslie*, Armando Rosario-Lebron, Veronica L. Yurchak, Guihua Chen & Cerruti Hooks
University of Maryland, Department of Entomology
*University of Maryland Extension, Charles County

Farmers’ decisions about when and how to terminate their cover crops can enhance, decrease, or have no effect on weed establishment in the following crop. Winter cover crops are typically terminated with a burn-down herbicide during early to late spring, which also kills any germinated weeds before planting the cash crop. A residual herbicide is often included as a tank-mix to provide some protection from future weed germination. This practice provides weed suppression through cover cropping and herbicide usage. However, timing of cover crop termination can affect weed populations by influencing cover crop biomass and the amount of residue that remains on the soil surface.

Delaying cover crop termination has the potential to improve weed suppression through greater cover crop biomass accumulation. However, this delay can negatively affect the subsequent cash crop if the growing cover crops deplete soil moisture with increased evapotranspiration. As such, effects of cover crop termination date on weed management must take into account its impact on soil water availability. The Maryland Department of Agriculture’s cover crop program includes a new incentive for the 2019/2020 cover crop season called the Extended Season option. This new incentive encourages late termination by paying farmers an additional $15 per acre when they agree to terminate their cover crops after May 1. However, concerns about soil moisture and yield of the following soybean crop may keep some farmers from participating in this program.

Field experiments were conducted at two sites in Maryland in 2013 and 2014 to examine how varying the termination date and method of barley cover crop affects the weed community, soil moisture and yield in the following no-till soybean crop. This experiment compared four treatments: (1) early-kill with burn-down and residual herbicides (EK), (2) late- kill with burn-down and residual herbicides (LK), (3) late-kill with a flail mower and residual herbicides (FM), (4) and a fallow/bare-ground check with burn-down and residual herbicides (BG). Terminating the barley late or just prior to soybean planting resulted in significantly greater barley biomass accumulation in LK and FM than EK (Table 1).

Table 1. Mean cover crop or winter weed biomass at time of herbicide burn-down or flail mowing.

1EK = early kill, LK = late kill, FM = flail mow, BG = bare-ground. 2Different letters indicate statistically significant difference (P < 0.05).

Weed density, soil coverage and species diversity were measured to determine effects of cover crop management tactics on weed suppression. Weed growth measurements were conducted after soybeans reached the early vegetative growth stage and continued until soybean canopy closure. Soil moisture was measured throughout the season at Beltsville using electrical resistance sensors to determine the effect of cover crop management on soil moisture dynamics. Soybeans were harvested using small plot combines. Weed composition, in terms of species and their relative abundances, was similar between study sites. There were 16 weed species identified at each site; the most abundant grass weeds at both sites were large crabgrass (Digitaria sanguinalis) and goosegrass (Eleusine indica). The most abundant broadleaf weed at Beltsville was white clover (Trifolium repens), while white clover was second in abundance to carpetweed (Mollugo verticillata) in Upper Marlboro. The EK treatment had the greatest weed coverage (Fig. 1). In Upper Marlboro, total weed coverage was greater in EK than FM or LK treatments and more grass weeds were found in EK than LK plots (Fig. 2a). In Beltsville, BG had significantly more annual broadleaf weeds than FM or LK treatments (Fig. 2b). However, the number of perennial weeds was similar among treatments (Fig. 2c).

Figure 1. Mean percent weed coverage at Beltsville during 2013 and 2014. Different letters indicate significant differences between treatments.

Soil moisture levels fluctuated with rainfall events throughout the growing season, and appeared to show a response to increased water demand of soybean plants following canopy closure both years. There was no significant effect of treatment either before or after canopy closure on soil moisture either year. Similarly, soybean yields were similar among all treatments.

Figure 2. Mean weed counts from quadrat samples. Values are pooled across both years. Different letters indicate significant differences (P < 0.05) between treatments (A) or between treatment/site combinations (B).

In summary, the EK treatment had the lowest cover crop biomass and the highest weed pressure among treatments. However, increased biomass in LK and FM did not result in better weed suppression than the BG treatment, and there were no differences in weed pressure between LK and FM. Method and timing of termination had no significant effect on soil moisture or yield. Results from this experiment suggest that mechanically terminating a cover crop can be as effective as using a burn-down herbicide for managing weeds in a subsequent soybean crop if a residual herbicide is used, and that delaying cover crop termination or herbicide application until just prior to soybean planting can result in reduced weed pressure during the season.

Soybean farmers in Maryland generally kill their cover crop early partially out of concern that cover crops will dry out soils ahead of planting the next crop. During this experiment, there was no evidence of lower soil moisture or suppressive effects on soybean emergence, growth, or yield in cover crop treatments terminated late. From the perspective of weed management, these results encourage cover crop management strategies that delay termination until just prior to planting the soybean crop. As such, results from this study show that timing of cover crop termination is important for managing weeds and that in some instances mechanical termination of cover crops may substitute chemical termination without a loss in weed suppression benefits. Although this may not be true under all growing conditions, the best practice for weed management among methods tested during this study is using a combination of narrow row spacing and terminating the cover crop as late as possible, as this provides the best opportunity for preventing the need for further herbicide applications later in the season. Results of this study show that farmers can opt-in to the Maryland Department of Agriculture’s new Extended Season incentive without expecting negative impacts on soybean growth or yield.

For more details: view the full-text article in the Crop Protection Journal (https://doi.org/10.1016/j.cropro.2018.10.020).

Acknowledgements

We thank crews at the Upper Marlboro and Beltsville Research and Education Centers for logistics in establishing field trials. This work was supported by Hatch Project No. MD-ENTO-9107/project accession no. 227029 from the USDA National Institute of Food and Agriculture, Maryland Soybean Board and USDA NIFA EIPM number 2017-70006-27171.

When it Comes to Nitrogen Leaching, Not All Cover Crop Practices Are the Same

Ian Goralczyk, Nathan Sedghi, and Ray Weil
University of Maryland, Department of Environmental Science & Technology

Cover crops are subsidized by taxpayers for use on more than 600,000 acres of agricultural fields in Maryland as part of an initiative to protect water quality and the Chesapeake Bay. As cover crops grow and take up nutrients, the water leaching from fields is cleaned up, especially with regard to nitrogen. However, the way that cover crops are typically managed may not be optimal for improving water quality. The Weil lab’s previous work has shown that the effectiveness of cover crops in reducing N leaching during the winter is dramatically affected by how early the cover crops are established, with cover crops planted in mid-October having little impact on N leaching compared to those planted a month earlier. The challenge is to find ways of getting cover crops established in early September, a time frame usually not possible with the typical practice of drilling cover crop seed after harvesting the corn or soybean cash crop. For this reason we studied a mixed species cover crop (radish, rye, and crimson clover) that was interseeded into standing soybeans canopies as compared to the standard practice of post-harvest drilling, and a no-cover crop control. We conducted the replicated experiment on two coastal plain fields with soils of contrasting textures formed in silty/clayey sediments, and in sandy sediments.

igure 1. Undergraduate researcher in the Weil Lab, Ian Goralczyk, installing a suction lysimeter for collecting soil porewater samples.
Figure 1. Undergraduate researcher in the Weil Lab, Ian Goralczyk, installing a suction lysimeter for collecting soil porewater samples.

This experiment was established at the Beltsville Facility of the Central Maryland Research and Education Center, with funding from Shore Rivers, LLC and the Maryland Soybean Board. The early planted cover was planted by broadcasting seed into a standing soybean canopy at leaf yellowing using a hiboy air-seeder on September 11, 2017. In each field, suction lysimeters were installed (Figure 1) to one-meter depth and samples were collected using a 85 kPa vacuum approximately every two weeks between December 17, 2017 and May 7, 2018. Soil pore water samples were filtered to remove particulate matter and frozen until they were analyzed for NO3-N and NH3-N on a LaChat® Flow Injection Analyzer.

One field had a silt loam surface texture and a clay loam subsoil (Russet-Christiana Complex). The other field had a loamy sand surface texture and sandy loam subsoil (Evesboro-Downer Complex). By utilizing fields of contrasting soil textural classes we can determine the effectiveness of these cover cropping methods with a range of soil conditions in order to broaden the scope of this study.

Cover crop use made a major difference in nitrate concentrations measured in the porewater collected at 1 m depth (Figure 2). Nitrate concentrations were reduced most where cover crops were established the earliest. As expected, the nitrate concentrations in the leaching water, as well as the impact of early cover crop establishment, were greatest on the sandy soil site.

While there were some individual samples that exceeded the EPA safe drinking water standard for nitrate-N (10.0 ppm), the average of all individual treatments was below this standard, and nitrate concentrations were consistently lower for the early interseeded cover crop treatment. A major reason why lower nitrate concentrations at one meter depth were observed for cover cropped plots is that the nitrate was taken up by cover crops roots and largely translocated to the aboveground plant tissue. This process captures the N before it leaves the potential rooting zone and recycles it to the surface soil where it may be released for use by future crops. This release could lead to decreased need for fertilizer nitrogen application to the following corn crop. Our data suggest that if similar cover crop interseeding practices (using aerial or ground-based methods) were applied on a large scale on commercial farms, the reduction in nitrogen loading to the Chesapeake Bay could be substantial. We can also conclude that early-planted cover crops are effective for reducing nitrate leaching on soils with a range of textural classes.

While these results are promising, it is important to note that they represent only one year out of a three year project, and that more data will be collected on different fields and with different cover cropping methods. We hope to provide farmers with guidance on optimizing cover crop species mixtures, planting dates and methods in order to enhance the impact of cover crops on nitrogen pollution while also improving soil health and farm profitability.

Figure 2. Nitrate-N concentrations in porewater from 1 m depth in fields of contrasting soil texture. Average of all sample dates during the 2017-18 winter-spring leaching season (N=33). Error bars are one standard error.
Figure 2. Nitrate-N concentrations in porewater from 1 m depth in fields of contrasting soil texture. Average of all sample dates during the 2017-18 winter-spring leaching season (N=33). Error bars are one standard error.

Department Announces Healthy Soil Biomass Pilot Program

Maryland Department of Agriculture News Release

ANNAPOLIS, MD – The Maryland Department of Agriculture has launched a Healthy Soil Biomass pilot program for farmers who were approved to participate in the department’s 2018-2019 winter cover crop program, but were unable to plant all of their acreage. The pilot program will pay these farmers a flat rate of $45/acre to plant qualifying small grains in leftover, unplanted fields to create a healthy soil biomass and protect water quality in nearby streams, rivers and the Chesapeake Bay.

The pilot program works in a similar way to the department’s traditional cover crop program, but it is a separate and distinct program with its own set of rules and requirements. Only farmers who were previously approved to plant cover crops this fall are eligible to participate. These farmers may plant up to 500 acres of qualifying small grains on “leftover fields” that they did not plant in traditional cover crops. Farmers have a choice of planting methods, but only wheat, rye or triticale may be used as the seed source. The planting deadline for the pilot program is December 1.

Farmers will need to certify acreage planted under the program with their local soil conservation district within one week of planting.  Kill-down may not take place before May 1.  The healthy soil biomass pilot program is a performance-based cost-share program. To qualify for the $45/acre payment, a sufficient amount of biomass will need to be present by May 1. Research shows that delaying kill-down of a cover crop contributes substantial amounts of carbon and root matter to the soil while providing protective mulch that guards against erosion.

The healthy soil biomass pilot program is administered by the Maryland Agricultural Water Quality Cost-Share (MACS) program and funded by the Chesapeake and Atlantic Coastal Bays Trust Fund. For more information, farmers should contact their local soil conservation district or the MACS program at 410-841-5864.

Maryland Department of Agriculture Extends Deadline for Planting Cover Crops to November 12

ANNAPOLIS, MD – Due to a late harvest and saturated soil conditions, the Maryland Department of Agriculture has extended the Nov. 5 planting deadline by one week for farmers who have signed up to plant cover crops this fall with the Maryland Agricultural Water Quality Cost-Share (MACS) Program. Farmers now have until Nov. 12 to plant qualifying cover crops of rye, wheat and triticale on their fields.

The extension is only available to farmers who use the following planting methods: no till, conventional, or broadcast with light, minimum or vertical tillage. With the extension, farmers must certify their cover crop with their local soil conservation district within one week of planting and no later than Nov. 19 in order to be reimbursed for associated seed, labor, and equipment costs.

“Extending the planting deadline allows farmers enrolled in our popular Cover Crop program to plant more acres of protective cover crops on their fields this fall in order to control soil erosion, reduce nutrient runoff, build healthy soils, and protect water quality in the Chesapeake Bay and its tributaries,” said Hans Schmidt, the department’s Assistant Secretary of Resource Conservation. “Importantly, the extended forecast calls for mild temperatures which should allow for germination to take place.”

Cover crops are cereal grains that grow in cool weather. They help slow down rainwater runoff during the winter, when the soil would otherwise be exposed, and recycle any nutrients remaining in the soil from the previous summer crop. Cover crops are a key feature in Maryland’s efforts to reduce the amount of nutrients entering the Bay.

Maryland’s Cover Crop program is funded by the Chesapeake Bay Restoration Fund and the Chesapeake and Atlantic Coastal Bays Trust Fund. For more information, farmers should contact their local soil conservation district or the Maryland Agricultural Water Quality Cost-Share Program at 410-841-5864.

Deadline for Aerial Seeding and Aerial Ground Seeding of Cover Crops Extended to Oct. 14

Maryland Department of Agriculture Press Release

Due to poor weather resulting in unsafe flying conditions over the last several weeks, the Maryland Department of Agriculture has extended the aerial seeding and aerial ground seeding deadline for farmers who signed up to plant cover crops in their fields this fall with the Maryland Agricultural Water Quality Cost-Share Program (MACS). Farmers now have until Oct. 14 to aerially seed or aerially ground seed their cover crops using high clearance broadcast seeders.

Only the following cover crop species are eligible for this extension: barley, rye, wheat, and triticale. Farmers must certify their aerial seeded cover crop acreage with the local soil conservation district within one week of planting to be reimbursed for associated seed, labor and equipment costs.

In recent weeks, rain, fog and wind has prevented aerial applicators from safely seeding cover crop fields. Extending the planting deadline will allow farmers to plant more acres of cover crops on their fields and achieve greater water quality benefits for Maryland waterways and the Chesapeake Bay. According to University of Maryland experts, moisture conditions are adequate for germination.

Maryland’s Cover Crop program is funded by the Chesapeake Bay Restoration Fund and the Chesapeake and Atlantic Coastal Bays Trust Fund. This program provides grants to farmers who plant small grains on newly harvested fields to reduce nutrient runoff, control soil erosion, build soil health, and protect water quality in the Chesapeake Bay and its tributaries.

For more information, farmers should contact their local soil conservation district or the Maryland Agricultural Water Quality Cost-Share Program at 410-841-5864.

Maryland Department of Agriculture Announces 2018-2019 Cover Crop Sign-Up

ANNAPOLIS, MD – The annual sign-up period for Maryland Department of Agriculture’s cover crop program will take place June 21 – July 17 at soil conservation district offices statewide. This popular grant program provides farmers with cost-share assistance to offset seed, labor, and equipment costs to plant cover crops on their fields this fall to control soil erosion, reduce nutrient runoff, build healthy soils, and protect water quality in streams, rivers and the Chesapeake Bay. Governor Larry Hogan has allocated approximately $22.5 million for Maryland’s 2018-2019 Cover Crop Program.

“Planting cover crops this fall is a great way to recycle or scavenge any nutrients that were not used by corn and other cash crops by the end of the growing season,” said Secretary Joseph Bartenfelder. “To give farmers more planting options, several new small grain/legume cover crop mixes were approved for payment this year. I urge farmers to take advantage of our popular cover crop program.”

Cover crops help protect waterways from nutrient runoff, control soil erosion, and improve soil health. As they grow, cover crops recycle unused plant nutrients remaining in the soil from the preceding summer crop. Once established, they work all winter to protect fields against erosion spurred on by wind, rain, snow, and ice. In addition to their water quality benefits, cover crops help build healthy soils, increase organic matter in the soil, reduce weeds and pests, and provide habitat for beneficial insects. They can even help farm fields recover more quickly from drought and extreme rainfall. Studies have shown that planting cover crops in the fall can increase yields of cash crops like corn and soybeans after only a few years.

Maryland’s Cover Crop Program provides grants to farmers who plant small grains such as wheat, rye, barley, and oats, brassicas, and forage radish on their fields following the fall harvest. To help create diversity, eligible cover crop species may be mixed with radish and legumes including clover, Austrian winter peas and hairy vetch using a variety of two and three-species mixes.

Cover crops cost-shared through this program receive a base rate of $45/acre and up to $30/acre in add on incentives for planting early and using other highly valued planting practices. The aerial seeding deadline is October 7. Maryland’s nutrient management regulations require farmers to plant cover crops to help protect water quality when organic nutrient sources are applied to fields in the fall. Double-crop soybeans may be planted aerially at a reduced reimbursement rate and farmers may harvest their cover crops, but payment for this option is no longer offered. Program eligibility requires that the farm has a current nutrient management plan.

Maryland’s Cover Crop Program is administered by the Maryland Department of Agriculture and the state’s 24 soil conservation districts through the Maryland Agricultural Water Quality Cost-Share (MACS) Program. Applicants must be in good standing with MACS and in compliance with Maryland’s nutrient management regulations. Other restrictions and conditions apply. Funding is provided by the Chesapeake Bay Restoration Fund and the Chesapeake and Atlantic Coastal Bays Trust Fund. For more information, farmers should check their mailboxes for announcements or visit the department’s website.

Guess the Pest! Week #4 Cover Crop ID Answers

Guess The Pest Logo

 

 

 

 

 

Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Congratulations to John Swaine for correctly identifying the cover crop species and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Photo 1: Austrian Winter Peas

Photo 2: Hairy Vetch

Photo 3: Winter Rape

Photo 4: Forage Radishes. This was a little misleading since we had a good winter kill. If you look carefully, you can see the divots where the radish roots once were.

If you didn’t guess all the species correct or if you would like to find out about some of the research and demonstrations that are going on in Delaware, join us at one of the Cover Crop Twilight Tours this coming week.

You will have an opportunity to walk through the demonstrations planted last fall including cover crop species, cover crop mixes, and cover crop planting date comparisons. Discussions will also include issues associated with terminating cover crops, slugs and insect issues, effects on weeds, soil health, and planting.

For more specifics visit www.DECCnetwork.com

Guess the Pest! Week #4

Guess The Pest Logo

 

 

 

 

 

Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Test your pest management knowledge by clicking on the GUESS THE PEST logo and submitting your best guess. For the 2018 season, we will have an “end of season” raffle for a $100.00 gift card. Each week, one lucky winner will also be selected for a prize and have their name entered not once but five times into the end of season raffle.

This week, one lucky participant will also win A Farmer’s Guide To Corn Diseases ($29.95 value).

You can’t win if you don’t play!

Yes, even IPM folks sometimes get tired of talking about pests, so for this week, we are going to have some fun guessing the cover crop species. If you think you know your cover crops, submit your best guess for each picture below:

Photo 1

Photo 2

Photo 3

Photo 4

What are those cover crops?