Field Crop News
Website Address: http://fcn.agronomy.psu.edu/
October 20, 2009 Vol. 09:31
IN THIS ISSUE:
- Weather Outlook
- Keep it on the Field!
- Overgraze Pastures this Fall Before Over-seeding a Legume
- Fall Harvesting of Alfalfa
- Reducing the Potential of Prussic Acid Poisoning
- Troubles with Slugs
- Thinking About Weed Control in Winter Cereals?
- How Much Straw Can I Remove and Still Maintain Soil Quality?
- Soil Compaction Threat Increased?
- Keystone Crops and Soils Conference
- Cover Crop ‘Show and Tell’
Weather Outlook — Paul Knight, Pennsylvania State Climatologist
A changeable weather pattern, leaning toward the cool side, will dominate the next two week’s weather. Above average temperatures are expected in many sections on Wednesday and much of Thursday as clouds steadily increase. A cool front from the north will stall across the region late Thursday and it will become the focus of wet weather on Friday afternoon into Saturday morning. Most places will receive between 0.25 and 0.75 inches in this period. A surge of chilly air will arrive on blustery winds late Saturday and Sunday. A reinforcement of cool air is expected next Tuesday, but it may be short-lived. There are indications that the final few days of October (next Wednesday through Saturday) may turn rather stormy across the nation, particularly in the East. Odds favor a wet spell, perhaps followed by very cool, windy conditions.
There are some signs that November will turn rather mild in this region and December will become quite cold and perhaps snowy. The development of a moderate El Nino in the Pacific portends a wetter winter (and probably snowier) in the state with the period December-February expected to average below normal temperatures with much of the chill coming early and late in the season and a spell of mild, Pacific air possible during January. Though not likely, it is possible that a two to three week spell of extreme cold may encompass the Northeast during the first half of this winter (between Dec 1- Jan 15).
Keep It On the Field! (At least until spring) — Jonathan Rotz, Franklin County
As the grain harvest continues more and more fodder is spread on the fields. Corn fodder is still used by many as a bedding material, however we ought to take a moment and consider what the best management of this valuable material is.
First off I’m not going to tell you that you shouldn’t use this for bedding. It is well understood that this is a vital product for some farmers however typically our timing is poor for harvesting corn fodder. As we continue to better understand what happens in our soils we find that carbon has a large influence on our soil quality including water holding capacity, soil organisms and nutrient cycling. This carbon can come from a variety of sources including crop residues such as fodder. These residues will decay and amend the top soil creating food for our soil organisms and nutrients for future crops. Understanding how these residues amend the soil allows us to better understand the negative affects we can have by harvesting these products. With that being said, if we harvest the fodder, bed with it, then return it all to the field we typically do not significantly decrease the organic matter or nutrient value of the bedding. This is the typical system we see on our local dairy farms so as long as the fodder will be kept in the local system soil quality is not largely affected.
Time of harvest is the next consideration. When fodder is left on the field it covers the soil limiting the amount of erosion from wind and water. One of the largest factors for erosion, even in no till, is the impact of rain drops on the soil surface. As the rain drop hits a bare soil surface it actually breaks some of the soil off making it available to leave the field via runoff, if the soil surface is not left bare this event will not happen. Fodder and other residues on the field actually break the force of the rain drop limiting erosion. Additionally, when heavy rains come residue also acts as a method for slowing runoff from a field. This also limits the ability of the water to move sediments from the field. Cover crops also perform the same tasks; however, due to the timing of grain harvest we typically cannot establish a cover crop after harvest. With these considerations fall harvest of fodder is not preferable in terms of soil conservation. Fodder that is left on the field until just prior to planting will decrease the soil losses. An additional benefit to this method is some of the nutrient in the fodder will actually leach during the winter thus more fertility will be available to next year’s crop prior to fertilization.
I do realize that some may be overloaded with nutrients or looking to clean up a field for alfalfa planting in which case fodder harvest may be advantageous but typically we work against ourselves by harvesting in the fall. You may have to buy some straw to fill the bedding gap until spring; however I do believe it will be well worth it in the long run.
Overgraze Pastures This Fall Before Over-Seeding a Legume — Marvin Hall, Penn State Forage Specialist
Adding legumes to cool-season pastures is the best way to increase forage quality and animal performance. Legumes increase protein, forage digestibility and intake when added to a grass pasture. As a bonus, legumes make their own nitrogen which reduces fertilizer costs.
The biggest challenge to establishing legumes into an existing grass pasture is competition by the grass on new, slow growing seedlings. Anything you do to reduce competition and slow down grass growth will help. One of the best ways to slow down spring grass growth is to graze it hard now. Heavy grazing this fall prior to frost seeding this winter or no-till seeding next spring will weaken the existing grass, reduce its spring growth and remove much of the old dead thatch. This will give the new legume seedlings a better chance to get started.
While you’re at it, also collect some soil samples. Then analyze them and apply any needed fertilizer. Legumes often need extra phosphorus and sometimes lime to improve soil pH.
Fall Harvesting of Alfalfa — Marvin Hall, Penn State Forage Specialist
Taking a fall harvest of alfalfa is really about assessing the benefits and risks. For example, you probably wouldn’t take a harvest in the fall if you knew that a very cold and open (no snow cover) winter was waiting just ahead. The risk of loosing the alfalfa stand would be greater than the benefits of taking the harvest. The benefits and risks of fall harvesting must be assessed in each situation to determine if the benefits are greater than the risks.
Below are some questions to help make the decision about taking a fall harvest or not.
- Do you really need the forage? If you already have plenty of forage to make it until next spring then why risk a fall harvest.
- Is it a younger stand? Older alfalfa stands are more likely to winter kill or suffer winter injury following a fall harvest than younger alfalfa stands.
- Is the soil pH and fertility at optimum? Adequate soil pH and fertility minimizes the risk of fall harvesting.
- Is the field well drained? Alfalfa on well-drained soils is less likely to suffer winter injury than alfalfa on poorly-drained soils.
- Did any previous harvests this year have flowers before cutting? Alfalfa harvest schedules which allow alfalfa to flower once during the season, minimizes the risk of winter injury.
If you answered YES to questions 2–4, then you are at a low risk. However, for each NO answer to these questions your risk increases.
Reducing the Potential of Prussic Acid Poisoning — Marvin Hall, Penn State Forage Specialist
Sudangrass, forage sorghums and sorghum-sudangrass crosses (all in the genus Sorghum) contain a non-poisonous chemical called dhurrin. If these plants are damaged by freezing, chewing or trampling), the dhurrin is converted into prussic acid (cyanide) which is potentially very dangerous for animals eating these crops.
Factors Affecting Prussic Acid Content In Plants
Species. The vegetative portion of all sorghums contains dhurrin. Generally, however, prussic acid content in sudangrass is about 40 percent less than in most other sorghums. As a group, the sorghum-sudangrass hybrids have more prussic acid than sudangrass. Crosses have now been developed that contain extremely low quantities.
Plant Parts. In the sorghums, young leaf blades normally contain higher prussic acid levels than old leaf blades or leaf sheaths or stems. The seedheads are low in prussic acid, and the seeds contain none.
Maturity. Highest prussic acid levels are reached before the boot stage. As plants mature, the stalks make up a greater proportion of the plant, causing prussic acid content in the total forage to decrease.
Drought. Severe drought is probably the most common cause of prussic acid poisoning. Drought-stricken plants are hazardous to feed because they are mostly leaves.
Freezing. Forage is usually considered safe to pasture or feed as green chop 5-6 days after a killing frost.
Fertilizer. If high N rates are applied to soils deficient in phosphorus and potassium, prussic acid levels usually increase.
Safe Feeding of Potentially Hazardous Forages
Pasture. Sorghum that has wilted and dried 5–6 days after being killed by frost is considered safe for grazing. The risk of prussic acid poisoning can be reduced by feeding ground cereal grains to the animals before turning them out to graze. The chance of problems on pasture can be further reduced by using heavy stocking rates (4–6 head per acre) and rotational grazing to avoid cattle selectively grazing the leaves. If new shoots develop after a frost the crop should not be grazed until this new growth is 2 feet tall.
Green Chop. Green chop forage is usually safer than the same material used for pasture because it is not selectively grazed. Whereas in the case of pasture only the leaves may be eaten, with green chop material the total plant is consumed. Stems act as safety devices ‘diluting’ the high prussic acid content of leaves.
Silage. Sorghum silage is generally safe for feeding. Although it could contain toxic levels of prussic acid while in storage, much of the poison escapes as a gas during fermentation and when being moved for feeding. However, as a precaution, do not feed new silage for at least 3 weeks after harvesting and storing.
Hay. The prussic acid content of sorghum hay decreases as much as 75 percent while curing and is rarely hazardous when fed to livestock.
Troubles with Slugs — John Tooker, Penn State Entomology Specialist
We are certainly hearing about slug troubles this fall. With the cooler temperatures, slugs seem to be feeding incessantly, attacking newly planted cover crops and fall-planted small grains. Slugs of course are most often problematic in no-till systems and thrive in high moisture, high residue fields. Unfortunately for farmers with slug problems this fall, many management tactics need to be implemented in spring, but there are few options that farmers can implement this fall that stand a good chance of reducing slug populations next spring.
Most slugs have a single generation per year with overwintering eggs hatching in spring and slugs developing through spring, summer, and fall. As winter approaches, slugs lay eggs, which overwinter and hatch the next spring. Anecdotal evidence of seeing apparently full-size slugs early in spring seems to suggest that some adults can survive until next spring and resume feeding.
To assess slug populations this fall, it is necessary to scout fields. Because slugs are most active at night, this can be done easily by placing in fields wooden boards (siding or even roofing singles can also work well) of some standardized size. Slugs will hide under these boards during the day providing an opportunity to gauge population size. Leave the boards in place for a few day and count slugs. Keep track of which fields have the largest populations and then in the spring scout these fields first for damage. There is a good chance that high fall populations will lead to high spring populations and a need for chemical control.
Another tactic that may be of use is removing debris from fields. Some folks that do not use cover crops remove stubble for bedding and these more-exposed fields would tend to dry out more quickly, which would leave them less likely to harbor damaging slug populations. This tactic of course would not be available to farmers regularly using cover crops. Another tactic that has anecdotal support for helping to decrease slug populations is incorporating some degree of fall tillage. Shallow disking or turbo tillage provides some incorporation that should help knock back slug population in spring. A grower looking to test this option could easily leave a portion of the field untreated to see if the management was effective. If slug problems are particularly bad, growers might consider fall applications of metaldehyde baits. Such applications can be effective, but are not the most efficient use of these baits because some adult slugs may have already laid eggs and the chemical treatment might not contribute too much to reducing spring population.
A final point worth mentioning in the struggle against slugs is that natural enemies have a lot of potential to contribute to slug suppression. Some ground beetle and harvestman (aka daddy long legs) species are voracious slug predators; unfortunately, natural enemies populations in many crop fields never get a chance to build because of regular use of broadcast insecticides. Many growers tank-mix insecticides in the spring as an insurance policy against other potential crop pests. but it should be recognized that applications of insecticides in absence of crop damage are economically dubious and have the potential to disrupt often unrecognized natural enemy-provided control.
Thinking about Weed Control in Winter Cereals? — Bill Curran and Dwight Lingenfelter, Weed Science
A number of weeds can be problematic in winter wheat and barley. Most recently, several weedy grasses have become more problematic in the Northeast in small grains. Annual or Italian ryegrass (Lolium multiflorum) is more common to the south in Maryland and Virginia, but can also be found in some fields in Pennsylvania. ACCase or Hoelon resistant ryegrass is a problem in some fields. The annual brome species have also become problematic in our fall seeded small grains. Downy brome (Bromus tectorum) is generally considered the most common of these different winter annual grassy weeds, and although herbicide susceptibility can differ, the biology, ecology and control are similar for the different Bromus species. Most of the cultural control tactics aimed at reducing the problem of downy brome should have already taken place (delayed planting, manage for seed production the previous year, etc.). So, you may be thinking about using an herbicide (see Table 1).
For grass control, Axial XL and Hoelon can be used on barley and wheat, while Osprey, Finesse Grass & Broadleaf, Maverick, and Prowl H2O are only labeled for wheat. Prowl H2O received a supplemental label for weed control in wheat back in late fall, 2006. On medium textured soils, apply 1.5–2.5 pt/acre after wheat emergence (1st leaf stage) and prior to weed emergence. Emerged weeds will not be controlled with this treatment. If weeds have already emerged, you can tank-mix Prowl H2O with other wheat herbicides that provide some postemergence control. For Italian ryegrass, Axial, Hoelon, and Osprey have been effective treatments, especially when applied in the fall to emerged grasses. Hoelon will not control ACCase resistant biotypes and Axial performance has varied with the resistant biotype. For Bromus species, Maverick has been the most consistent product in our tests followed by Osprey. Fall application is generally better than spring. For Maverick, soybeans can be planted within 5 months of application on soils with a pH <6.5 and a minimum of 30 inches of cumulative precipitation; with higher soil pH and less rainfall, the soybean recrop restriction is 12 months. Soybeans can be planted after 90 days of application with Osprey.
PowerFlex is a new herbicide from Dow AgroSciences labeled for winter wheat. The active ingredient is pyroxsulam, an ALS inhibitor. We do not yet have any experience with PowerFlex at Penn State, but the label claims control of downy brome and other Bromus species with fall application and Italian ryegrass with both fall and spring application. The label also includes a number of broadleaf weeds including common chickweed, henbit, and a number of mustard species. The typical use rate will be 3.5 oz/A (plus necessary adjuvants) and can be applied from the 3-leaf to jointing growth stage of wheat. The minimum rotation interval in Pennsylvania to soybean is 3 months.
As you look at the list of available herbicides in Table 1, a number of these products are ALS inhibitors. Both Virginia and Maryland have reported ALS-resistant common chickweed in wheat probably due to the long history and use of Harmony products as well as some other ALS inhibitors. Be alert for the development of new resistant weed problems and adjust the program accordingly.
| Herbicide | Grass Control | Grass Suppression | Broadleaves |
|---|---|---|---|
| (* Achieve, Axial, Finesse, and Hoelon can be applied to barley.) | |||
| Axial (and Achieve) |
|
— |
|
| Finesse Grass & Broadleaf |
|
|
|
| Finesse | — |
|
|
| Hoelon |
|
— |
|
| Maverick |
|
|
|
| Olympus Flex (pending approval) |
|
|
|
| Osprey |
|
|
|
| Prowl H2o | — |
|
|
How much Straw can I Remove and Still Maintain Soil Quality? — Sjoerd Duiker, Soil Management Specialist
Straw harvesting is such a common phenomenon in Pennsylvania that we don’t even question its practice. However, we recognize that the straw contains carbon and plant nutrients that we remove from the land. Carbon is the foundation block of soil organic matter, the most important indicator of soil quality. Soil organic matter positively influences soil structural stability, porosity, water infiltration, water holding capacity, and cation exchange capacity. To maintain soil organic matter content, a minimum of crop residue needs to be returned to the land. But perhaps below-ground residue and stubble is enough to accomplish that. Recently, a review of wheat and barley straw removal was published in the journal ‘Better Crops with Plant Food’. Studies reviewed for this article showed that, to maintain soil organic matter content, no straw should be removed when wheat yields were lower than 50 bu/A. In the reviewed trials, wheat was grown in rotation with corn, barley, as a monoculture, or in a wheat/fallow system. The minimum annual above-ground biomass required to maintain soil organic carbon content ranged from 0.3-4.5 tons/A/yr, a very large range. However, in most studies the required return of biomass was 2,000-4000 lbs/A/yr. All studies were done with tillage, and most were done with moldboard plowing. The average wheat yield in Pennsylvania was 56 bu/A in 2009, suggesting normal straw removal would have a negative impact on soil quality in our state. To compensate for the negative effects of straw removal, farmers should cut wheat high, use no-tillage, plant cover crops after wheat harvest, and integrate wheat production in a rotation that includes a high-residue producing crop such as grain corn or perennial crops such as grass or alfalfa.
Reference: Tarkalson, D.D., B. Brown, H. Kok, and D.L. Bjorneberg. 2009. Impact of removing straw from wheat and barley fields: A literature review. Better Crops with Plant Food 93(3):17–19.
Soil Compaction Threat Increased — Sjoerd Duiker, Soil Management Specialist
Farmers are eager to harvest soybeans and corn but the fields are very soggy after significant snow and rainfall over the past week. The compaction threat is therefore very considerable. As a minimum, a farmer should wait to access fields until no significant ruts are formed. However, it may be impractical to wait for some low-lying wet spots to dry out before venturing into harvest. If ruts are formed in these spots, it may be necessary to do some limited tillage to smooth the soil in the spring prior to planting. It is probably not a good idea to do tillage this fall prior to cover crop establishment due to suboptimal soil conditions for tillage. Rut formation is significantly reduced by using flotation tires or tracks due to their bigger footprint. Remember to inflate the flotation tires to their lowest permitted pressure to carry the load — Ohio State research showed that inflation pressure basically controlled the benefit of flotation tires. Contact your tire sales person about the proper inflation pressure for your tires.
Typically, rut formation is much more severe in tilled fields than in long-term no-till fields. This is due to the fact that the tilled soil has a loose consistency, while the no-till soil has a firm matrix interspersed with macro-pores. It is these macro-pores that explain the high water infiltration rates of no-till soils. You may be wondering if tillage will be needed next spring after harvest operations on no-till soils this fall. Our research has shown that, except if ruts are formed, there seems to be little benefit to tilling these fields. Localized tillage may be needed where ruts are formed, but it is usually disadvantageous to till the whole field because of the expense involved and the destruction of the no-till history of the field.
Finally, make sure you use designated traffic lanes to haul the grain out of the field to limit the impact you have on the most precious and amazing resource you have: The Soil!
Upcoming Events
Keystone Crops and Soil Conference — October 27 & 28 Holiday Inn, Grantville, PA
Hosted by: Penn State Capital Region Extension Agronomy Team & PennAg Industries Association
Conference Details: Who Should Attend?
Certified Crop Advisers, Ag Service Providers, Agronomists, Certified Pesticide Applicators, Nutrient Management Specialists and Planners, Crop Producers, Ag Specialists, Federal/State/County Agency Staff and anyone else with interest in the agronomic industry.
What You Can Expect
This two day conference will provide numerous educational sessions providing up-to-date agronomic information. This year’s Seminar will offer Certified Crop Advisers the opportunity to earn up to 14 CCA Continuing Education Units (CEUs). CEUs will be available in the following categories: Nutrient Management (NM); Crop Management (CM); Soil and Water Management (SW) and Pest Management (PM). All credits noted in this brochure are pending approval and subject to change. Pesticide, Nutrient Management and Manure Hauler/Broker Certification credits have also been applied for.
Registration Information
Simply complete the form in this brochure and return with your payment to PennAg Industries Association by October 16, 2009. Registration rates are as follows: Both Days: $180 One-Day Only: $110. For more information about registration or the program, please contact Amy Bradford at 717-651-5920 or via email at abradford@pennag.com.
Hotel Reservations
A block of rooms has been reserved at the Harrisburg/Hershey Holiday Inn at a special rate of $108 plus tax per night for a single or double room. To reserve a room in the block, please call the Harrisburg/Hershey Holiday Inn directly at 717-469-0661 and mention the Keystone Crops and Soils Conference. Reservations should be made no later than October 16, 2009. After this date, rooms may be reserved on an as-available basis. For more information about the hotel, including directions, visit www.stayholiday.com.
Cover Crop Demonstration Trial coming to a Location near You
Cover Crops are a key component to manage soil health and productivity. For generations farmers have benefited from the “Green manures” which helped maintain soil quality and productivity. Today we are “re-discovering” what our grandfathers knew and depended upon for consistent yields and sustainable crop production.
Cover crops not only protect the soil but they also scavenge and accumulate large quantities of nutrients such as nitrogen and phosphorus which could potentially escape the farm. Cover crops provide a living root system in the soil which benefits and stimulates soil biology and increases soil health and quality. They can be especially beneficial in no-till crop production. Combining the benefits of no-till and cover cropping has been shown to make the conversion to no-till smoother and faster.
Weed suppression, and organic matter addition are two additional benefits of cover crops. Research is finding that well managed cover crops can even help increase yields for the following crop. Penn State extension agronomists, local seed companies, farmers, and other agricultural professionals have been experimenting with new and traditional species for cover crop use.
The public is invited to Come, See, Touch and Learn about both traditional and non-traditional species. Oats, rye, ryegrass, hairy vetch, winter peas, forage radish, crimson clover, several mixtures and numerous other “exotic” species were established around the state this fall and are available for viewing. You can compare fall growth, rooting characteristics, weed suppression, biomass, etc. between the species and discuss species characteristics with extension and industry professionals. Check with your local Penn State Extension Educator to see if a trail is available for viewing in your county.
October 23, 10am–12pm Franklin County Cover Crop Walk Jonathan Rotz, jdr21@psu.edu, 717-263-9226
To find the demonstration site, take I-81 to exit 17, turn left (if coming from the North) and go approximately 1 mi. The site is located on the right hand side of the road. Watch for signage the day of the field day.
October 28, 9:30am–2:30pm New and Emerging Cover Crops Field Day Cedar Meadow Farm 679 Hilldale Road Holtwood, PA See http://www.cedarmeadowfarm.com/FieldDays/ for more information
October 30, 9:30am–12pm Cover Crop Walk Bryan Garman Farm 201 Bridgeville Rd East Earl, PA 17519 Jeff Graybill, jsg18@psu.edu, 717-394-6851
November 10, 9:30am–12pm Lancaster County Cover Crop Walk Landisville Research and Extension Center 1446 Auction Road Manheim, PA 17545 Jeff Graybill, jsg18@psu.edu, 717-394-6851
November 10, 10:30am–2pm PA No-Till Alliance Cover Crop Walk Joel Meyers, joelmyers@myersfarm.com, 814-574-1319
November 10, 10am–12pm (Raindate, November 17) York County Cover Crop Walk John Rowehl, jer2@psu.edu, 717-840-7408
November 19, 10–11:30am Berks County Cover Crop Walk Mena Hautau, mmh10@psu.edu, 610-378-1327
November 19, 3–4:30pm Northampton County Cover Crop Walk Juniperdale Farms 653 Jones Hill Rd Pen Argyl, PA Tianna DuPont, tdupont@psu.edu, 610-746-1970
November 20, 10–11:30am Montgomery County Cover Crop Walk Parkhouse, Royersford, PA Andrew Frankenfield, adf13@psu.edu, 610-489-4315
Contact Information
Contact information for article authors and contributors can be found at:
- State Specialist — http://cmeg.psu.edu/specialists.cfm
- County Educators — http://cropsoil.psu.edu/people/extension/extensionedlist.cfm
Contributors: Extension Agents: Jonathan Rotz (Franklin), Kevin Fry (Armstrong), Susan Alexander (Jefferson), John Rowehl (York), Mena Hautau (Berks), Jeff Graybill (Lancaster) and Bill Waltman (Potter). State Specialists: John Tooker-(Entomology), Ron Hoover (On Farm Research), Sjoerd Duiker (Soils), Dwight Lingenfelter (Weed Science) and Bill Curran (Weed Science).
Editor: Jeffrey Graybill, CCA Lancaster County
Upcoming Events
Real time pest and heat unit activity: http://agsci.psu.edu/news/spotlight/pa-pipe
Calendar of Events: http://www.events.psu.edu/cgi-bin/cal/webevent.cgi?cmd=opencal&cal=cal209&
If you have any questions or would like to suggest a topic, please contact your local Extension Educator.
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