Ag Connection
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This Month in Ag Connection
Alfalfa Fall Management
Good Harvest and Storage Techniques Reduce Silage Problems
Use Your Microwave Oven to Test Forage Moisture
Keep Silage Fresh During Feeding
Using Cereal Grains for Forage
Electronic Resources on Forages
Safety at Silage Time
August 1996
Volume 2, Number 8

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Publishing Information
Ag Connection is published monthly for Central Missouri Region producers and is supported by University Extension, the Commercial Agriculture program, the Missouri Agricultural Experiment Station and the College of Agriculture, Food and Natural Resources, UM-Columbia. Editorial board: Maryann Redelfs, Managing Editor; Parman Green, James Rogers, Mark Stewart, Melvin Brees, Don Day and Ron Alexander.

Comments or Suggestions?
Please send your comments and suggestions to Maryann Redelfs, Agronomy/Information Technology Specialist, University Outreach and Extension, 608 E. Spring Street, Boonville, MO 65233, call 660-882-5661, or send messages by e-mail to:

To send a message to an author, click on the author's name at the end of an article.

Alfalfa Fall Management

Alfalfa management in the fall involves balancing the need to harvest additional forage with the risk of winter injury to the alfalfa stand. While several environmental factors are uncontrollable, many other factors are.

Uncontrollable Factors

  1. Fall hardening - Periods of cool temperatures are required in the fall for alfalfa to develop resistance to cold temperatures. Sudden drops in temperature to unseasonable levels in the early fall will cause problems.
  2. Snow cover of 6 inches or more protects alfalfa plants from severe cold.
  3. Cold temperatures - Even hardy varieties can be injured by two weeks of temperatures below 5 to 15 degrees.
  4. Midwinter thaws cause alfalfa to break dormancy and result in less resistance to freezing. Cold resistance is lost much faster than it is achieved. Severe temperature fluctuations above and below freezing can also result in plant heaving.
  5. Excessively wet soil in the fall reduces hardening and predisposes alfalfa to winter injury. Icing of excess surface moisture or sleet can result in smothered plants and/or the accumulation of toxic substances, such as carbon dioxide, ethanol, and methanol.

Controllable Factors

  1. Varieties developed for winter hardiness and disease resistance will better tolerate late fall cuttings.
  2. Soil fertility management, particularly potassium (potash), is vitally important for developing plants with increased winter hardiness.
  3. Cutting management - The more cuttings that have been harvested, the more plant reserves are reduced and the potential for winter injury is increased. Alfalfa needs at least 30 days of re-growth prior to a killing frost to establish root reserves. These root reserves are needed to maintain plant vigor and to begin spring re-growth. Younger alfalfa stands tend to survive winters better due to lower disease infestation and less physical damage.
  4. Stem and leaf stubble left standing in the field over the winter catch snow and help insulate the soil and crown of the alfalfa plants. Dale Watson, University Extension Livestock Specialist, maintains that the importance of this factor is difficult to over emphasize!

Source: "Alfalfa Management Guide"; North Central Regional Extension Publication - NCR547, available through your University Extension Center for $5.00. (Parman R. Green, Farm Management Specialist)

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Good Harvest and Storage Techniques Reduce Silage Problems

Many silage storage problems can be prevented if the silage is harvested at the proper moisture level, suitable stage of maturity and packed well.

Silage heating is generated by the oxidation of the plant carbohydrates. This can happen if oxygen is trapped due to insufficient compaction during the filling process or if air leaks into the silo.

Once silage reaches a temperature of 120 F or greater, the silage begins to caramelize. When forage is caramelized, feed energy is depleted and the protein is heat damaged. The cattle will eat the silage well, but the nutritional value will be low.

The main causes of mold are slow filling, too long a chop, slow feed out, air leaks, low moisture content or a poor job of packing the silo as it is filled. If low moisture is a problem, water can be added during filling to raise the moisture level of forage being ensiled. Mold can result in the cattle refusing to eat the silage and a lower nutritional value.

Other Problems
Rancid or vinegar odors and seepage are caused by filling when the crop contains excessive moisture, inadequate fermentation or low plant sugar. Excessive moisture can also cause problems with unloading if the silage freezes.

Many silage storage problems can be prevented if the silage is harvested at the proper moisture level, suitable stage of maturity and packed well. (Dale Watson, Livestock Specialist and Ron Alexander, Agronomy Specialist)

Other Resources on Silage:

Listing of recommended plant maturity, moisture content, and chopping length for silage harvest.

G04590: Corn Silage

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Use Your Microwave Oven to Test Forage Moisture

Knowing the moisture content of forages at silo filling reduces silo seepage, improves the nutrient content, and enhances the ensiling and storage processes. You can measure the moisture content in a few minutes using a microwave oven and a small scale. Use the following procedure:

Tools Needed
Microwave oven, small scale, paper plate or small paper bag and scissors. A scale that measures ounces can be used although it takes longer to dry the material because a larger sample is needed. A gram scale lets you use a smaller sample and the calculations are easier and more accurate.


  1. Obtain a representative forage sample.
  2. Use the scissors to chop the sample into pieces one to two inches long.
  3. Spread the sample as much as possible over the paper plate or place it in the small paper bag.
  4. Weigh the plate or bag containing the sample. (It will simplify the process if you start with a total of 100 grams)
  5. Put a glass of water one-half full in a back corner of the microwave.
  6. Place the plate or bag containing the silage (estimated 50 to 75 percent moisture) in the microwave and set at 100% power for three minutes.
  7. Remove the sample from the oven and stir or shake the sample. Return it to oven and set the time for two minutes (if the forage is hot, stir and cool the sample before proceeding with the drying process).
  8. If the forage sample feels dry, weigh the plate or bag of dry material and place it in the oven for 20 to 30 second intervals. Continue this process until the weight of the dry sample is constant. If the sample chars, use the previous recorded weight.
  9. Calculate as follows: percent moisture = ((wet weight - dry weight) / wet weight) x 100.

Example: wet weight of sample is 100 grams and the dry weight of the sample is 30 grams:
((100-30)/100) x 100 = 70% moisture

Warning: This can create an odor that stays with the microwave and can affect the taste of next food cooked. A small, inexpensive microwave just to be used for forage testing may be a good investment. (It's cheaper than paying for forgiveness after the household microwave smells like burnt silage.)

Maturity, Moisture Content and Cutting Length for Silage Harvest

G04590: Corn Silage

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Keep Silage Fresh During Feeding

Trench Silos
Summer: Remove a minimum of 4 to 6 inches per day from the face of the silo. The higher the air temperature the more silage needs to be removed from the face to prevent sour silage.
Winter: Remove a minimum of 3 inches per day from the face of the silo.
Upright Silos
Summer: Remove 3 inches per day from the surface of the silo.
Winter: Remove 2 inches per day from the surface of the silo.

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Using Cereal Grains for Forage

Central Missouri will probably get that two weeks of dry weather sometime in late July or August for which Missouri is famous. When pastures become brown and relatively unproductive, farmers may look to late August and early September seeding of small grains.

Researchers at Purdue suggest that wheat is a better choice than rye, barley, or winter oats because it yields nearly as much dry matter as rye or barley, more than oats, and is higher in quality than rye. Wheat is better adapted to heavier soils than barley and oats and offers a better spring grazing opportunity than rye.

Marion Brown, a former UMC forage specialist, reported that wheat supplied more and better pasturage than other cereals in the spring in southeast Missouri.

Spooner, in Arkansas, found that wheat produced more animal gain per acre than oats or barley, but that oats did produce a higher daily gain.

Heavier seeding rates are recommended for cereals used for forage. Seven to eight pecks/acre for wheat should be sown when seeding for early autumn production.

Patterson, of Purdue, suggests that wheat for fall grazing be seeded three to four weeks before the Hessian fly free date (October 6-7 in Central Missouri). That would put the seeding date for Central Missouri at about the first week of September.

Grazing was more severe than clipping, probably because grazing animals were allowed to remove more foliage to a shorter height than when clipped. Research has found that the same amount of forage was produced when clipped to a two-inch height than to a four-inch stubble, but a clipping interval of 60 days compared to 15 days nearly doubled yields.

Nitrogen influenced yields of small grain forage more than phosphate and potash. Forage yields were increased with each increase in nitrogen until the rate of 120 pounds per acre. Wheaton reported that one-half more phosphate and potash was needed for forage than for grain alone, and that a split application of 30 and 60 pounds of nitrogen was usually adequate for maximum forage production of wheat.

Adding clovers to the wheat does not help fall grazing since clovers produce most of their growth in the spring. Clover's contribution to small grain forage would be significant only if it was grazed into the late spring. Grazed cereals seldom have less than 14 percent protein and often as much as 21 to 24 percent.

Cereals may be harvested and used for hay and silage, but maturity at harvest is more critical in determining feeding value of cereals than it is with conventional forages. Cereals increase in dry matter and TDN (total digestible nutrients) until about the dough stage, but the soft dough stage only lasts a few days and then cereals become too mature for silage. Crude fiber increases and digestibility decreases rapidly following the dough stage. The dough stage occurs about 14 days after the heads emerge.

Small grains can be used for forage and harvested for grain without decreasing the grain yield. Wheaton reported that cattle should be removed from cereal fields before the heads inside the shoots are two inches above the soil surface to avoid reduced grain yields.

Taller, late maturing varieties usually produce more forage than shorter, early maturing varieties. High grain varieties may not necessarily be high forage producers. (Marion Gentry, Agronomy Specialist)

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Electronic Resources on Forages

Following are listservs and web sites that forage producers may find useful. To subscribe to a listserv, send a message to the address indicated. For more details on listservs, see the June 1996 issue of Ag Connection or contact Don Day or Maryann Redelfs by e-mail, or by telephone at 573-445-9792. (Don Day, Agriculture Engineering Specialist)


FORAGE-MG - A forage discussion group.
Subscription address:
Type: subscribe FORAGE-MG in the message body.
GRAZE-L A grazing discussion list. Topics include rotational grazing and other issues.
Subscription address:
Type: subscribe GRAZE-L <your name> in the message body.

World Wide Web Sites - Articles on forages from Virginia Tech., including research on bale storage options, controlled grazing, economics of forages, and many more topics. - Provides information on forages from Oregon State University and links to forage-related information worldwide.

Caution: Watch where information comes from. Be sure it is applicable to your area. Also, be cautious of the validity of information. Some information is based on some individual's opinion and some is based on research. Look for credentials of those who provide the information!!

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Safety at Silage Time

Packing silage is important to reduce losses in storage. When tractors are used to pack silage into bunker silos, overturns are common. The tractors should be equipped with a roll over protective structure and seat belts. Equipping it with dual wheels will help prevent overturns. Do not use older tractors with tricycle front ends.

Keep the silage as level as possible until the silage near the side of the silo is packed. Level the silage and pack it in layers six to twelve inches deep for the most packing, and to prevent air pockets from developing. Use caution near the sides of the silo, especially if the silage is deeper than the height of the sides. Front end loaders should be kept low to reduce chances of overturns.

Another place to exercise care at silage time is around upright silos. Fermenting silage produces nitric oxide, nitrogen dioxide, and nitrogen tetroxide. These gases can cause coughing, difficulty in breathing, or nausea. Higher concentrations can cause the lungs to fill with fluid, resulting in death. The presence of these gases is often indicated by dead birds or flies under the silo chute.

The highest concentrations of these gases are produced during the first 48 hours after silage is added to the silo, but they may be present for the next four weeks. Avoid entering a silo for three to four weeks after silage has been added. If entry must be made during this time, ventilate the silo with the silage blower or ventilation fans for at least 30 minutes before entry and leave the fans on as long as someone is inside. Use a longer ventilation time if the silo is more than 24 feet in diameter or if the silage surface is more than 15 feet from the top of the silo. Even if more than four weeks has passed, thoroughly ventilate the silo before an initial entry is made.

Since silo gases are heavier than air, they may flow down the silo chute and collect in the silo room, if there is one. To reduce chances of developing a hazardous gas concentration, keep the doors between the silo room and other parts of the building closed and the silo room's windows and doors to the outside open. (Don Day, Ag. Engineer/Information Technology Specialist and Dave Baker, Assistant Program Director of Agriculture Extension, UMC)

Other Resources on Silage: G04590: Corn Silage

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University Extension Ag Connection - August 1996 -- Revised: August 21, 1997