“Ammoniation of Wheat Straw dramatically improves Feeding Value”
by Chris Reinhardt, feedlot specialist
Although it’s a strange time to discuss winter forage needs, it’s about the right time to be planning what to do with wheat straw left after wheat harvest. “Planning” here is the key word.
Sometimes, forage is cheap and abundant; other times, everything has value. Ingredients we never would considered as suitable for feeding some years are other times in high demand and bring a good price. But while we want to give every opportunity due consideration, we’ve got to be sure to know what the true nutritional value of a feedstuff is, as well as any potential for toxicity.
Wheat straw has traditionally been fed to beef cows and can provide energy to gestating cows if supplemented with protein; however, ammoniation of the straw can effectively improve its feed value. Lignin (the “glue” that holds the cells together and gives strength to the stalk) normally prevents ruminal microbes from breaking down much of the cellulose in mature forages. Ammoniation breaks down the bonds between lignin and the cellulose and hemicellulose, allowing access for rumen microbes, and releasing energy for the cow to use.
Ammoniation not only adds nitrogen and increases the crude protein content of the forage, but also improves digestibility and consumption of the forage as well. Simply put, untreated wheat straw has very little energy and protein; whereas ammoniated wheat straw has protein and energy values similar to moderate quality prairie hay.
The ammoniation process is relatively simple and inexpensive. Stack the straw bales in either a 3-2 or 3-2-1 pyramid. Leave several inches between adjacent bales to allow ammonia to flow freely between the bales within the stack. Cover the stack with a single sheet of 6 mil plastic and completely seal the plastic around the base of the stack with soil. Any holes in the plastic should be sealed with tape.
Insert a hose from the anhydrous ammonia nurse tank under the plastic at the base of the stack at the midway point of the stack and seal the plastic around the hose. A manifold can be used to disperse the ammonia more evenly throughout the bale stack.
Most literature sources recommend applying anhydrous ammonia at the rate of 3% of the bales’ dry weight; however, recent K-State data suggests that 1.5% may be nearly as efficacious but has roughly half the cost. At a 3% addition rate, 60 lbs of anhydrous ammonia will be added for each ton of hay. For simplicity, a nurse tank can be used containing the exact amount of anhydrous ammonia for the amount of hay in the stack, and the tank can be allowed to empty completely. Apply the ammonia slowly to prevent rapid expansion and breaking of the plastic.
WARNING: Anhydrous ammonia is very toxic to the skin, eyes, and respiratory tract. Therefore, only conduct ammoniation in an open, well-ventilated area, always work upwind from the ammonia source, and always wear goggles and rubber gloves when exposed to the anhydrous ammonia. Have abundant clean water available in the event of exposure of the eyes or skin to the anhydrous ammonia.
The time required for the chemical breakdown to occur depends on ambient temperature: allow 1-2 weeks to cure if daily temperatures are in the 80’s or 90’s; increase this time to 4-6 weeks if ammoniating during the winter. Prior to feeding, remove the plastic and allow the bales to aerate for several days to allow excess ammonia to escape. Corn stalks can also be successfully ammoniated and forage quality effectively improved in a similar manner.
The value of wheat straw and corn stalks can be dramatically improved by ammoniation. The cost of ammoniation is presently $20-40 per ton of forage, depending on application rates, which makes the ammoniated crop residue a very cost-effective alternative to prairie hay which might need to be purchased and hauled from a distance. In the present market, all forage has some value; however, it’s imperative to test all forages to determine what that value is.