Treating Forage with Ammonia
is Feed Option During Drought

UNL Extension educators and soil/nutrient management specialist discuss treating forage with ammonia.

by Tom Holman, Gary Hergert & Aaron Berger

The heat and drought have caused cattle producers to look for methods of adjusting to local conditions. Many who don't want the expense of additional feeds are considering early weaning and selling replacement heifers. However, an alternative may be ammonia treatment of low-quality forages.

For wheat producers who choose to bale their straw, this provides an opportunity for additional income, but there are drawbacks to removing straw. Many producers leave wheat residue to enhance soil moisture storage for future crops. Some nutrients are also removed in the straw, which can affect future crops.

Irrigated wheat produces considerably more straw; a portion can be removed and still leave some residue. Straw production rates can be predicted fairly accurately if you know grain yield. The Harvest Index (ratio of grain to total dry matter) for most semi-dwarf wheat varieties planted in western Nebraska is about 0.3. A 40-bushel (bu.) wheat crop will produce about 5,600 pounds (lb.), or 2.3 tons, of straw. An 80-bu. wheat crop will produce more than 5 tons of straw per acre.

Straw is an ideal source of forage to ammoniate for beef cows. With wheat harvest so early in many areas, some are considering planting hay millets behind straw harvest to produce another (hay) crop to increase income. Crop production budgets for millet and sorghum-Sudan crosses following irrigated wheat are currently being developed by Jessica Johnson, Extension educator in ag economics at the Panhandle Research and Extension Center.

Treatment of low-quality crop residues with anhydrous ammonia improves their digestibility, as shown in the accompanying table. Moisture content of the forage is important. Ideally, best results of ammoniation occur when the forage is greater than 10% moisture. Also, ammoniation of forages is successful when the air temperature is higher than 80° F. Adequate heat has not been a problem of late across most of the High Plains, but waiting until fall is not advised.

 

Table 1: Change in forage digestibility, intake and crude protein after ammonia treatment
	Digestibility (%)		Crude Potein (%)		Increase in
Forage	Untreated	Treated	Untreated	Treated	Intake (%)
Wheat straw	39	48	3.7	9.7	18
Corn stalks	48	56	6.2	11	22
Bean straw	41	47	4.9	14	16

Ammoniation is accomplished by covering the straw pile with plastic and applying ammonia to the covered straw. Procedures and how to estimate the amount of anhydrous to apply are listed in UNL Extension Publication EC89-265, which can be found at http://digitalcommons.unl.edu/.

Currently, anhydrous is selling for $820 per ton, wheat straw is averaging $85 per ton, labor is estimated at $12 per hour and alfalfa hay is estimated at $180 per ton at 18% crude protein, 15% moisture and 56% total digestible nutrients (TDN) (59¢ per lb. of protein and 19¢ per lb. of TDN).

Assuming that 6-8 mill black plastic sheets are selling for 7¢ per square foot, a 40 x 100 sheet would cost $280, and plastic pipe would cost $35. Following are some estimated costs to ammoniate a ton of wheat straw:

Equipment (plastic and pipe):	$9.33
Anhydrous Ammonia:	$24.60
Labor:	13¢
Bale wheat straw:	$15.82
Total:	$49.88 per ton

The cost to ammoniate wheat straw at 89% dry matter, 9.7% crude protein equals 172.66 lb. of protein equals 29¢ per lb. of protein and 6¢ per pound of TDN.

If cattle producers want to purchase wheat straw at $85 per ton and ammoniate it, their costs would total (without trucking) $134.88, or 78¢ per lb. of protein and 16¢ per lb. of TDN. Ethanol byproducts or other feeds such as beet pulp and soy hulls can be fed along with wheat straw to meet cow nutrition needs. By evaluating and comparing feed options, producers can develop the most cost-effective ration to meet livestock needs.

Editor's Note: This article was written as part of the "At the Center" series. "At the Center" is a regular series of articles that share the University of Nebraska–Lincoln research and knowledge concerning topics of interest to the Nebraska Panhandle.

[Click here to go to the top of the page.]