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4/9/2012 - 4/15/2012

Agricultural Specialists Added to Expand ISU FARM Research Project

Mark Honeyman, ISU Research Farms

Iowa State University Research and Demonstration Farms and ISU Extension have hired two agricultural specialists to expand the ISU Farmer Assisted Research and Management, or ISU FARM, project.

Micah Smidt and Zachary Koopman will work at the Northern Research Farm near Kanawha, and the Agricultural Engineering/Agronomy Farm near Boone, respectively.

ISU FARM will extend the reach of the research farms near Kanawha and Boone. A network of cooperators in the surrounding counties will be established to conduct research on their farms.

Smidt and Koopman will assist cooperators in choosing topics related to corn or soybeans, designing and laying out the study, planting the test strips, applying the experimental treatments, and collecting and analyzing the data. Smidt also will work with farmers in northeast Iowa near the ISU Northeast Research Farm near Nashua.

Smidt of Kanawha earned a bachelor’s degree in agronomy from Iowa State in 2010, and has experience as a crop consultant and production agriculture. Koopman of Boone earned a bachelor’s degree in agronomy from Iowa State in 2009, and has worked with custom application, crop protection and production agriculture.

ISU FARM is supported by the local associations that own the research farms: North Central Iowa Research Association, Kanawha; Northeast Iowa Agricultural Experimental Association, Nashua; and the Committee for Agricultural Development, Ames. Ag Ventures Alliance, a Mason City business development group for value-added agricultural ventures, and the Iowa Soybean Association also have invested in the program.

 

Mark Honeyman is the interim director of Iowa State Research Farms. He can be reached at 515-294-4621 or honeyman@iastate.edu.

Is it Too Late to Dig Miscanthus for Spring Planting?

By Emily Heaton  and Nicholas Boersma, Department of Agronomy

Giant Miscanthus (Miscanthus × giganteus) is a perennial warm-season grass used for bioenergy, and is being planted on thousands of acres in Missouri and Arkansas this spring. Given the warm spring, and the high level of interest in Miscanthus this year, we have been getting lots of questions around propagation and planting.

A sterile hybrid, Giant Miscanthus is most commonly planted from rhizome pieces when the soil temperatures have reached 50 F. Most farmers get their rhizomes from a commercial supplier, but those people who just want to play around with the new crop have been planting small plots that they can then dig up and propagate into larger stands at their leisure. Here are some things to consider if you are propagating and/or planting rhizomes this spring.

  1. If you want to dig up rhizomes from an established stand, it is best to do this while the stand is dormant, that is, after it has died back in the fall and before in emerges in the spring.
  2. If you are not replanting immediately, dig and separate the rhizomes, then keep them cool (approximately 40 F), making sure they don’t dry out.
  3. If your Miscanthus has already emerged, you can still dig, but if you have expanded leaves, it is getting too late. Once the shoots get over 10 inches tall on average, you will start losing plants, and it is best to wait until the following year to dig. A rule of thumb might be that for every inch the stand is over 8 inches, you will lose 5 percent of the potential plants.
  4. Plant rhizomes in a weed-free row (can use strip tillage), making sure that all of the rhizome is covered, but not too deep; at least part of it should be within 2 inches of the soil surface.
  5. Good weed control is essential at establishment. Planting on a grid will allow for cultivation after the Miscanthus has emerged. Harness and Harness Xtra are labeled for use on Miscanthus for pre-emergent weed control.
  6. Rhizomes can take a while to emerge, anywhere from three days to three weeks, typically, with some not emerging until late in the season. This is frustrating, but resist the urge to dig anything up or replant until three weeks, warm temperatures and some good rain have had a chance to work. 

   
Shoots of Giant Miscanthus emerging from a clump of rhizomes in a recently tilled field near Ames, Iowa.  Most shoots are still in the whorl, with only a few small emerged leaves. Once more leaves have unrolled, this field should not be divided this year.

 

Emily Heaton is an Iowa State University agronomy professor with extension responsibilities in biomass production. She can be contacted by emailing heaton@iastate.edu or calling 515-294-1310.  Nicholas Boersma is a research associate in the agronomy department. He can be contacted at nboersma@iastate.edu or calling 515-851-1024.

Cold Injury to Alfalfa

By Steve Barnhart, Department of Agronomy

Alfalfa fields are growing well across most of Iowa. The next few nights have frost or freeze warnings, with predictions of night low temperatures as low as low 20s. Low temperatures, whether visible frost is present or not, may affect the growth of both established forage plants, as well as newly emerged seedlings.

Cold injury risk is reduced where vegetative growth or cover is protecting the new seedlings or forage growth lower in the plant canopy. Air temperature, a few feet above a bare or grass covered soil surface, is what is measured and reported. Plant tissue temperature is influenced by leaf surface color, density of the plant canopy, air movement within the canopy, the temperature of the soil, and likely more subtle conditions. The air within the forage canopy is likely ‘layered’, meaning the temperature at the top of the canopy is colder than the temperature at the soil surface, and below the soil surface in the taproot and crown area. Simple statements about the influence of the reported temperature can be misleading. To complicate things a bit more, tolerance of leaves to frost varies somewhat among varieties and individual plants, and is not always related to winter hardiness of the variety.

New Forage Seedings 
At emergence, alfalfa and most winter hardy forage grass and legume seedlings have good cold tolerance. But, spring cold snaps can hurt new seedings too. I tend to agree with the article from Oregon that states; “For alfalfa, at second trifoliate leaf stage (and older) seedlings become more susceptible to cold injury and may be killed by four or more hours at 26 F or lower temperatures. Alfalfa seeded with a companion crop survives lower temperatures and longer exposure times before showing frost damage.”

Established Stands
Well established, developing forage plants have lost their winter cold hardiness. Exposed tissue is susceptible to cold temperature injury. Several hours of 25-27 F temperature, or lower, will damage leaf tissue and may seriously damage buds and growing points.  Upper 20s F air temperatures will likely damage one to several sets of trifoliate leaves that were exposed at the top of the canopy. The buds and growing stem tips are somewhat more protected and often continue to grow normally. 

Where does that leave us? There will likely be leaf tissue damage in some parts of the state where overnight temperatures go 25 F to 27 F or lower for several hours. Slope position, soil temperature, companion crop of oats, wind, snow cover, all will influence what occurs in a particular field or part of a field.

Management Suggestions
The only management suggestion at the moment is to wait a week or so to see what the damage is. 

New seedings
Seedlings that were frozen so that all trifoliate leaves are discolored and dying will not regrow. If new seedings were permanently damaged, consider re-seeding as soon as possible. Keep the good areas and drill into thin or damaged areas. Tillage may not be necessary. If you think that a cereal grain companion crop, still present, will be too competitive or will impede the reseeding, then tillage may be required.

Established stands  
A "light" frost/freeze where temps don't go below around 27 F or so for very long is likely to freeze several sets of trifoliate leaves on the alfalfa tops and set back growth rates for a while, but plants will grow out of it. No need to cut, although some growers seeking very high quality might do so if standing yield is high enough to justify harvest with the understanding that plants will be weakened by early cutting and should be allowed extra time to recover before the next cutting.

A freeze that penetrates about halfway down into the alfalfa canopy will likely kill the top-most stem tip/growing points. These plants will continuing to grow too, producing more branching below the freeze zone; others may produce new stems from below ground, crown buds. This kind of regrowth will be slow to initiate. If yield is high enough to justify harvest, and plants have reached 15 to 20 inches of height or bud stage, the stands  probably should be cut, knowing that extra time will be needed for recovery before the next cutting. If yield of standing crop is low, or the plants weren’t nearly ready to cut, probably best to just wait out the delay in regrowth. It will be hard to justify the time and expense of cutting/shredding with no immediate harvestable crop.

A colder, freeze likely will freeze plants all the way to the ground and kill the above ground stems. April frosts and freezes are not likely to be cold enough to damage underground crowns, so the plant is not dead. Harvest of frozen plants is warranted if yield is sufficient, but must be done immediately. If frozen plants collapse much of the biomass will be lodged. Frozen leaves will shatter quickly from stems as they dry, so good handling and harvest management is needed to salvage the forage. If you are not going to harvest this frozen plant material, there is no benefit from shredding damaged tissue, the new stems will grow up through the frosted, lodged stems.  

After a freeze that causes visible damage to alfalfa tissue, the plants are under some stress, and will be more susceptible to damage from foliar diseases and sometimes, insects, on regrowth, so continue scouting fields.

Replanting severely damaged new seeding may be necessary. If there has been widespread, sever cold injury to established stands, consider replanting a new alfalfa stand in an adjacent field.

 

Steve Barnhart is a professor of agronomy with extension, teaching, and research responsibilities in forage production and management. He can be reached at  sbarnhar@iastate.edu, or 515-294-7835.

Determining When to Harvest First Crop Alfalfa in a Warm Spring

Brian Lang, ISU Extension field agronomist
 
The exceptionally warm spring has alfalfa growth well ahead of normal, with some farmers expecting to harvest first crop in April.  Those that normally harvest first crop alfalfa by calendar date, often harvest in mid to late May. Harvest should be much sooner this spring, but when? Consider using the Predictive Equations of Alfalfa Quality (PEAQ) to determine when to harvest. PEAQ is a simple management tool to estimate alfalfa quality in the field to help predict the best time to harvest first crop.

PEAQ provides an estimate of alfalfa quality based on stage of plant development and stem height. This allows you to estimate standing crop forage quality with a yard stick and your observation of the stands stage of development; vegetative, bud or bloom. Just use these two factors with Table 1 in the PEAQ fact sheet to estimate relative feed value (RFV). Under the best harvest conditions, 10 to 20 percent of the forage dry matter will be lost at harvest. This amounts to approximately 15 RFV points for haylage and 25 RFV points for hay. Therefore, if you are trying to end up with 150 RFV alfalfa, you should consider harvesting the crop when PEAQ measurements estimate a RFV of 165 to 175 for the standing alfalfa crop in the field.

To help monitor the progress of alfalfa stands in Iowa, Extension created a PEAQ website where RFV determined by PEAQ are posted for various alfalfa fields across Iowa. To see these postings, go to PEAQ and click on “All Above Counties” in the lower right of the Web page. However, these postings are no substitute for monitoring your own fields. As you see in these postings, there are considerable differences from field to field, as expected, do to field location in the state, variety, harvest management, soil fertility, soil type and other factors that affect alfalfa growth and development.

 

Brian Lang is an Iowa State University Extension field agronomist serving northeastern Iowa. He can be reached at 563-382-2949 or bjlang@iastate.edu.



This article was published originally on 4/16/2012 The information contained within the article may or may not be up to date depending on when you are accessing the information.


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