Ammoniation of Forages
 
Ammoniation is an effective method for producers dealing with damp hay or low-quality forages. It offers two primary benefits:
 
Benefits of Ammoniation
  • Improved Nutritional Value: Ammonia (NH₃) adds nitrogen, increasing crude protein content and enhancing digestibility by breaking down lignin in mature forages.
  • Preservation: Ammonia prevents spoilage by destroying bacteria and moulds, allowing safe storage of higher-moisture forages. This reduces nutrient loss, field harvesting risks, and weather dependency.
 
Key Factors Affecting Ammoniation
  • Moisture Content: Minimum 12% moisture is required for effective NH₃ binding. Test forage before treatment to determine moisture and calculate ammonia application.
  • Timing: Treat forage soon after harvest for maximum benefit. Weathering reduces nutritive value and ammoniation response.
  • Temperature: Higher temperatures accelerate reactions and improve digestibility. Lower temperatures require longer treatment times.
  • Ammonia Rate: Crude protein improvement depends on the amount of NH₃ applied.
 
Impact on Nutrient Levels
  • Crude Protein: Manitoba Agriculture studies show 85–125% increases in crude protein when ammoniating at 3% NH₃ (dry matter basis).
    Example: Oat straw improved from 3.2% to 7.2% crude protein (125% increase).
  • Digestibility (TDN): Expect a 10–15% increase in TDN. For instance, straw with 45% TDN may reach ~50% after treatment.
  • Palatability & Intake: Research indicates reduced mould and improved intake, resulting in higher weight gains for cattle.
    • Weight Gain: Pregnant beef cows gained up to 1.43 lb/day on ammoniated forage compared to 0.31 lb/day on untreated forage.
·        Additional Benefits: Reduced spoilage, improved feed safety, and enhanced ration formulation flexibility.
 
Steps in the Ammoniation Process
1. Location Selection
  • Ensure easy access for anhydrous ammonia tanks and farm equipment.
  • Provide shelter to protect plastic and forage from wind and weather.
  • Choose a well-ventilated area to minimize health hazards.
  • Keep stacks away from buildings—ammonia concentrations (16–27%) can be explosive under extreme conditions.
    Safety Tip: Never smoke or use open flames near ammonia.
  • Space stacks 6–10 ft (2–3 m) apart to prevent trapped ammonia and reduce hazards.
 
2. Stacking
  • Stack forage to match the size of available plastic sheets (recommended: 6 mil black polyethylene).
  • Use one sheet if possible; avoid layering clear plastic over black (causes melting).
  • Check stack dimensions during stacking for proper coverage.
 
3. Sealing
  • Make the cover airtight; seal holes with duct or refrigeration tape.
  • Secure plastic against ballooning by weighting edges with sandbags or covering with soil in a trench.
  • Add tape around the middle of stacks and use netting or twine to prevent wind damage.
  • For high-moisture stacks, tighten plastic after 7–10 days to correct looseness.
 
4. Ammoniation
  • Use a perforated iron pipe (12 in diameter, ~22 ft long). The pipe is sealed to a closed, sharp point at one end and threaded at the other end. Holes, 3/16 inches (0.5 cm) in diameter, are drilled into the long pipe at 16 inches (0.4 m) intervals.   
  • The pipe must have a sharp point for insertion.
  • Attach pipe to ammonia source using a special adapter; seal entry point with tape or a plastic sleeve.
  • Dispense ammonia from a truck or trailer tank; cap pipe after 30 minutes or remove and reseal hole.
  • Safety Precautions:
    • Wear tight-fitting goggles and rubber gloves.
    • Keep water nearby for emergency flushing.
    • Stand clear during application to avoid escaping gas.
 
5. Application Rates
  • Protein Improvement: Apply NH₃ at 3–5% of forage dry matter weight.
  • Preservation Only: Apply NH₃ at 2% of forage dry matter weight.
  • Accurate application requires knowing forage moisture content and bale weight.

 

Ammoniation Calculation Example
Scenario:
  • 30 round bales of straw
  • Average bale weight: 400 kg (880 lb)
  • Moisture content: 15%
  • Target NH₃ application: 3.5% of dry matter weight
 
Step 1: Calculate Dry Weight of Forage
Dry Weight  =  Number of bales  x  Average bale weight  x  (100  - % moisture) / 100
 
Dry Weight  =  30  x  400  x  85 / 100  =  10,200 kg
 
Step 2: Calculate Required NH₃
 
NH₃ Required (kg)  =  Dry Weight  x  % NH₃ / 100
 
NH₃ Required  = 10,200  x  3.5 / 100  =  357 kg
 
Step 3: Convert to Liters
Use conversion factor:
 1 liter NH₃   =  0.76 kg
 
Liters Required  =  357 / 0.76  =  470 liters
 
Result:
  • Dry forage weight: 10,200 kg
  • NH₃ required: 357 kg (~470 liters)
Note: Exact NH₃ density varies with temperature; verify with supplier.
 
Removal of Plastic Sheets
  • Keep stacks covered for at least three weeks.
  • When removing:
    • Remove tape and belts before sandbags.
    • Pull plastic into the wind on a day when wind blows away from buildings.
    • Fold plastic carefully for reuse.
  • Feeding Timeline:
    • Ammoniated straw: Keep covered until a few days before feeding; use within 4–5 weeks to minimize nutrient loss.
    • High-moisture hay: Size stacks so they can be fed out in 3–4 weeks, especially in warm weather to prevent secondary fermentation.
 
Feeding Ammoniated Forages
  • Uncover stacks 3–4 days before feeding to allow excess ammonia to dissipate.
  • Palatability is generally excellent.
  • Ammoniated forage provides non-protein nitrogen (NPN):
    • Avoid combining with other NPN sources.
  • Use ammoniated crop residues and low-quality forages only in balanced rations based on feed analysis.