{"id":1064,"date":"2026-07-28T01:53:05","date_gmt":"2026-07-28T01:53:05","guid":{"rendered":"https:\/\/silage-baler.com\/?p=1064"},"modified":"2026-07-28T05:30:09","modified_gmt":"2026-07-28T05:30:09","slug":"silage-additives-beyond-inoculants-a-practical-review","status":"publish","type":"post","link":"https:\/\/silage-baler.com\/bn\/application\/silage-additives-beyond-inoculants-a-practical-review\/","title":{"rendered":"Silage Additives Beyond Inoculants: A Practical Review"},"content":{"rendered":"
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Silage Science \u00b7 Additives \u00b7 Fermentation Management<\/div>\n

Silage Additives Beyond Inoculants: A Practical Review<\/p>\n

Formic acid, urea, molasses, sodium benzoate, propionic acid \u2014 what each does, when it’s worth the cost, and which Australian crops and conditions benefit most from non-LAB additives.<\/p>\n<\/div>\n<\/div>\n

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Beyond LAB: The Additives That Address What Inoculants Cannot<\/h2>\n

Most Australian silage quality guidance focuses on LAB inoculants \u2014 the dominant and most well-researched category of silage additive. But LAB inoculants are not the only tool available, and they are not the right tool for every situation. Several non-inoculant additive categories address specific fermentation challenges that LAB-only strategies cannot fully resolve: direct acidification for very-high-moisture crops where LAB cannot establish fast enough, nitrogen supplementation for low-protein cereal silages, aerobic stability extension for silage in warm climates, and fermentation stimulation for low-WSC crops that cannot support reliable LAB fermentation.<\/p>\n

This article covers the six main non-inoculant silage additive categories used in Australian and international silage production: formic acid, formate salts, urea\/NPN, molasses, propionic acid\/propionates, and sodium benzoate. For each, we cover the mechanism, the evidence for benefit, the Australian conditions where it is justified, and the cost-benefit calculation that determines whether application is worthwhile. This article complements rather than replaces the inoculant discussion \u2014 many silage programmes combine LAB inoculants with one of these additives for specific cuts or conditions. For the LAB inoculant evidence base, our article on the best silage baler setup for high-volume dairy operations<\/a> covers the production context where additive decisions are made.<\/p>\n<\/div>\n

\"Silage<\/p>\n

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1. Formic Acid \u2014 Direct pH Reduction for High-Risk Silage<\/h2>\n

Mechanism and When It Outperforms LAB Inoculants<\/h3>\n

Formic acid (HCOOH) applied at 2 to 4 litres per tonne of fresh crop directly reduces silage pH without requiring any microbial fermentation activity. Unlike LAB inoculants that must produce lactic acid to reduce pH, formic acid achieves an immediate pH drop of 0.5 to 1.5 units at application \u2014 reducing the pH faster than any biological approach. This direct acidification is the only silage additive strategy that reliably suppresses clostridial fermentation in crops baled above 70% moisture (below 30% DM), where even high-rate LAB inoculants cannot acidify the mass fast enough to prevent clostridial establishment.<\/p>\n

In northern European silage production \u2014 where wet-harvest conditions are routine and perennial ryegrass is frequently baled at 65 to 75% moisture \u2014 formic acid or formate-based additives are widely used as standard practice. In Australian conditions, their primary application is the weather-emergency baling scenario: a paddock that must be baled at 72% moisture because rain is arriving in 3 hours. In this situation, formic acid at 3 litres per tonne fresh crop provides a meaningful quality improvement that LAB inoculant alone cannot match.<\/p>\n

\n\n\n\n\n\n\n\n
Crop Moisture<\/th>\npH Without Additive<\/th>\nLAB Inoculant Only<\/th>\nFormic Acid (3L\/t)<\/th>\nBest Choice<\/th>\n<\/tr>\n<\/thead>\n
55\u201365% (35\u201345% DM)<\/td>\n4.2\u20134.8<\/td>\n4.0\u20134.5<\/td>\n3.9\u20134.3<\/td>\nLAB inoculant<\/td>\n<\/tr>\n
65\u201372% (28\u201335% DM)<\/td>\n4.5\u20135.2<\/td>\n4.2\u20134.8<\/td>\n4.0\u20134.5<\/td>\nLAB + formic if available<\/td>\n<\/tr>\n
>72% (<28% DM)<\/td>\n5.0\u20136.5<\/td>\n4.5\u20135.5<\/td>\n4.0\u20134.6<\/td>\nFormic acid essential<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Cost and Safety Considerations<\/h3>\n

Formic acid costs AUD $3 to $6 per litre; at 3 litres per tonne fresh crop, additive cost per bale (assuming 500 kg fresh weight) runs AUD $4.50 to $9.00 \u2014 approximately 2 to 3 times the cost of a LAB inoculant application. Safety: formic acid is highly corrosive and must be handled with full PPE (goggles, rubber gloves, chemical-resistant apron). Direct skin contact causes immediate burns; inhalation of vapour causes respiratory irritation. Baler applicator systems for formic acid must be constructed of acid-resistant materials. This safety requirement limits formic acid use on farms without appropriate handling infrastructure.<\/p>\n<\/div>\n

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2. Urea (NPN) \u2014 Protein Enhancement for Low-CP Silage<\/h2>\n

Transforming Cereal Silage Into a Protein-Contributing Feed<\/h3>\n

Urea added to cereal silage at 4 to 6 kg per tonne fresh crop serves two functions simultaneously: it increases the crude protein of the silage (from a typical 8 to 10% CP for cereal silage to 14 to 18% CP post-treatment) and it provides an alkaline buffering effect that initially raises pH before the fermentation process proceeds to lower it. The protein enhancement works through rumen microbial use of non-protein nitrogen (NPN) from the urea \u2014 rumen bacteria incorporate the urea-derived ammonia nitrogen into microbial protein that is then used by the animal.<\/p>\n

For Queensland and northern NSW beef operations producing whole-plant sorghum or oat silage at 8 to 10% CP, urea treatment converts a maintenance-level roughage into a genuine protein-contributing feed that approaches 14 to 16% CP \u2014 significantly reducing purchased protein supplement requirements in the feeding period. Cost: urea at AUD $550 to $700 per tonne (2025 prices) at 5 kg per tonne fresh crop = AUD $2.75 to $3.50 per bale. Return: at 14% CP versus 9% CP (5 percentage point improvement), and a beef growing ration where 100 kg CP is worth AUD $60 to $80 above maintenance ration cost, the urea investment pays back across 8 to 12 bales consumed.<\/p>\n<\/div>\n

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3. Molasses \u2014 Fermentation Stimulator for Low-WSC Crops<\/h2>\n

Providing the Sugar That Difficult Crops Lack<\/h3>\n

Molasses applied at 5 to 20 litres per tonne fresh crop provides readily fermentable sugars (primarily sucrose and its hydrolysis products) that supplement the crop’s own WSC content. This is beneficial for crops with intrinsically low WSC \u2014 mature legumes (lucerne at full flowering, 3 to 5% WSC DM), tropical grasses (sugarcane tops, 6 to 9% WSC DM), and late-season cereal silage where WSC has been depleted by advanced maturity. Molasses provides the LAB fermentation substrate that the crop itself cannot supply in adequate quantities.<\/p>\n

The evidence for molasses benefit is strongest when used in combination with a LAB inoculant \u2014 the molasses provides the substrate, the inoculant provides the bacterial workforce. Using molasses without inoculant adds fermentable sugar that any available bacteria (including clostridia) can use \u2014 it does not selectively benefit LAB. Cost: molasses at AUD $180 to $280 per tonne at 15 litres per tonne fresh crop = AUD $1.35 to $2.10 per bale. Most effective on lucerne and tropical grass silage where WSC limitations constrain fermentation reliability.<\/p>\n<\/div>\n

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4. Propionic Acid and Propionates \u2014 Aerobic Stability at Feedout<\/h2>\n

The Feedout Problem: When Good Silage Deteriorates Fast<\/h3>\n

Propionic acid and its salt (sodium or calcium propionate) are antifungal additives that inhibit the yeast species responsible for aerobic deterioration at feedout \u2014 the heating and visible mould growth that occurs on the exposed face of an opened silage bale. Unlike formic acid (which acts at ensiling to reduce pH) or LAB inoculants (which act during fermentation), propionic acid\/propionates act at feedout to extend the period that opened silage remains cool and stable in hot conditions.<\/p>\n

This additive class is most relevant for Australian dairy operations in the Goulburn Valley and Murray-Darling Basin where summer temperatures exceed 35 to 40\u00b0C and opened silage bales in TMR yards can reach core temperatures of 45 to 55\u00b0C within 24 to 36 hours of opening. At these temperatures, yeast growth rates accelerate dramatically and DM losses from aerobic deterioration can reach 3 to 8% of the opened bale DM per day. Propionic acid at application rates of 1 to 2 litres per tonne fresh crop reduces yeast growth and extends the stable feedout window by 24 to 48 hours \u2014 meaningful in a high-temperature TMR operation where opening bales the evening before feeding is operationally convenient but aerobically risky.<\/p>\n<\/div>\n

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5. Sodium Benzoate \u2014 The Aerobic Stability Alternative<\/h2>\n

Sodium benzoate (E211) is a food-grade preservative that inhibits both yeast and mould growth in silage \u2014 providing aerobic stability improvement comparable to propionic acid at lower application volumes. Application rate is typically 1 to 2 kg per tonne fresh crop \u2014 significantly lower than the liquid volumes required for formic acid or molasses, making it easier to apply accurately through standard baler applicator systems. Cost: sodium benzoate at AUD $3.50 to $5.50 per kg at 1.5 kg\/tonne fresh = AUD $2.60 to $4.10 per bale.<\/p>\n

Sodium benzoate is used in Europe as a component of combination silage additives (often combined with potassium sorbate) for high-grain silage and high-moisture maize silage where aerobic stability is the primary quality concern. In Australia, its application is most relevant for Queensland and Northern Territory silage operations where tropical ambient temperatures make feedout stability a chronic management challenge.<\/p>\n

The 9YCM-850 bundling film wrapping machine<\/a> applies 6 to 8 layers of film that establishes the anaerobic environment within which all of these additives work most effectively \u2014 a poorly sealed bale with oxygen ingress will defeat any additive programme regardless of the product used. Film quality and layer count remain the primary determinants of silage quality; additives optimise outcomes within a well-sealed fermentation environment.<\/p>\n<\/div>\n

\"9YCM-850<\/p>\n

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Choosing the Right Additive for Your Situation<\/h2>\n
\n\n\n\n\n\n\n\n\n\n
Challenge<\/th>\nRecommended Additive<\/th>\nCost per Bale<\/th>\nPriority Rating<\/th>\n<\/tr>\n<\/thead>\n
Very high moisture (>72%)<\/td>\nFormic acid (3\u20134 L\/t)<\/td>\n$4.50\u2013$9.00<\/td>\nEssential<\/td>\n<\/tr>\n
Low-WSC legume silage<\/td>\nMolasses + LAB inoculant<\/td>\n$2.50\u2013$4.50<\/td>\nStrongly recommended<\/td>\n<\/tr>\n
Low-CP cereal silage<\/td>\nUrea (5 kg\/t fresh)<\/td>\n$2.75\u2013$3.50<\/td>\nRecommended for protein benefit<\/td>\n<\/tr>\n
Warm climate feedout instability<\/td>\nPropionic acid or sodium benzoate<\/td>\n$2.00\u2013$4.50<\/td>\nRecommended for TMR dairies<\/td>\n<\/tr>\n
Optimal grass silage at 35% DM<\/td>\nNone required<\/td>\n$0<\/td>\nNot justified<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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The Practical Rule: Match Additive to Specific Limitation<\/div>\n

No silage additive improves fermentation outcomes in crops that are already baled at optimal moisture with adequate WSC and applied with a well-calibrated LAB inoculant. Additives address specific limitations \u2014 high moisture, low WSC, low protein, aerobic instability \u2014 not general silage quality. Identify the specific limitation in your system before selecting an additive; applying the wrong additive wastes money and may not address the actual quality constraint.<\/p>\n<\/div>\n<\/div>\n

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Frequently Asked Questions<\/h2>\n
\nCan I apply formic acid through a standard baler inoculant applicator?<\/span>+<\/span><\/summary>\n
Not safely with a standard plastic or stainless steel applicator. Formic acid at agricultural application concentrations (85% pure) is highly corrosive to most metals and many plastics. The applicator system must be constructed of acid-resistant materials (HDPE, PVDF, or acid-grade stainless steel) and include a chemical-resistant pump, tubing, and spray nozzle. Retrofit formic acid application systems are available from silage additive suppliers in Australia \u2014 do not attempt to use a standard water-based inoculant applicator for formic acid.<\/div>\n<\/details>\n
\nDoes urea treatment affect silage palatability for cattle?<\/span>+<\/span><\/summary>\n
Urea-treated silage has a slightly elevated ammonia odour from the urea hydrolysis process during fermentation \u2014 most cattle adapt to this within 3 to 5 days of introduction. Introduce urea-treated silage gradually alongside untreated silage at 10 to 20% inclusion for the first week. Voluntary intake of urea-treated silage is typically 5 to 10% lower than equivalent untreated silage at initial introduction; this gap closes after the adaptation period. The protein premium (5 to 7 percentage points CP improvement) outweighs the minor intake depression in most beef growing ration contexts.<\/div>\n<\/details>\n
\nIs molasses application practical in a one-person baling operation?<\/span>+<\/span><\/summary>\n
Yes \u2014 molasses can be applied through the same baler pickup-level nozzle system used for liquid LAB inoculants, diluted to a flowable consistency with warm water (molasses at 20 to 25\u00b0C is pumpable; at below 15\u00b0C it thickens and requires dilution or heating). The higher application volume of molasses (15 to 20 litres per tonne fresh crop) requires a larger on-tractor tank than a standard LAB inoculant system (typically 100 to 200 litre capacity versus 20 to 50 litre for inoculant). A purpose-built molasses applicator tank mounted on the baler chassis is the cleanest solution for operations using molasses routinely.<\/div>\n<\/details>\n
\nCan I combine multiple additives in the same application?<\/span>+<\/span><\/summary>\n
Yes \u2014 some combinations work synergistically: LAB inoculant + molasses is a well-established combination for low-WSC crops; LAB inoculant + sodium benzoate addresses both fermentation speed and aerobic stability simultaneously; formic acid + LAB inoculant (applied separately) provides both direct acidification and biological fermentation support. Combinations to avoid: formic acid and LAB inoculants applied simultaneously in the same liquid \u2014 the acid pH kills the bacteria before they reach the crop. Apply formic acid and LAB inoculant through separate applicator lines or at separate application points.<\/div>\n<\/details>\n
\nAre silage additives registered as agricultural chemicals in Australia?<\/span>+<\/span><\/summary>\n
Formic acid, propionic acid, and some combination products require APVMA registration for use as agricultural chemicals in silage production. Urea is not regulated as an agricultural chemical in this context. Molasses is an unregulated food-grade product. Sodium benzoate is a food-grade preservative used in silage without specific agricultural chemical registration in Australia. Check the APVMA Public Chemical Registration Information System (PubCRIS) for the current registration status of any specific commercial product before use.<\/div>\n<\/details>\n<\/div>\n

\"9YG-1.25A<\/p>\n

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EverPower Baling Machinery \u00b7 Condell Park NSW 2200<\/div>\n

Discuss Your Silage Additive Programme<\/h2>\n

Tell us your crops, baling conditions, and specific fermentation challenges \u2014 we’ll help identify which additives address your limitations and which add cost without benefit.<\/p>\n

Request a Quote<\/a> About EverPower<\/a><\/div>\n
+61 2 9708 3322<\/a>  |  \u2709 sales@silage-baler.com<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

Silage Science \u00b7 Additives \u00b7 Fermentation Management Silage Additives Beyond Inoculants: A Practical Review Formic acid, urea, molasses, sodium benzoate, propionic acid \u2014 what each does, when it’s worth the cost, and which Australian crops and conditions benefit most from non-LAB additives. Beyond LAB: The Additives That Address What Inoculants Cannot Most Australian silage quality […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[35],"tags":[],"class_list":["post-1064","post","type-post","status-publish","format-standard","hentry","category-applications"],"_links":{"self":[{"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/posts\/1064","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/comments?post=1064"}],"version-history":[{"count":1,"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/posts\/1064\/revisions"}],"predecessor-version":[{"id":1069,"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/posts\/1064\/revisions\/1069"}],"wp:attachment":[{"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/media?parent=1064"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/categories?post=1064"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/silage-baler.com\/bn\/wp-json\/wp\/v2\/tags?post=1064"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}