Livestock manure is normally a storage problem: material arrives wet, odours develop, and the volume and weight of what has to be moved afterwards is set by how wet it stayed. A fermentation agent is added to accelerate the breakdown of the organic fraction so that the material stabilises faster, dries more readily and stops generating odour during the period it is held. It works by changing the rate of the process, not by suppressing the smell after the fact, and that distinction is the whole of the product case.
Product referenced in this article
Livestock Manure Fermentation Agent — application notes, specification table and document downloads for this range.
What is happening in a manure store
A store that receives manure daily develops a structure. The wetter material runs to the bottom and forms a low-oxygen zone; drier material sits on top and re-wets each time the store is emptied onto itself. The centre of the pile is oxygen-poor, warm and rich in readily degradable carbon, which is exactly the combination in which anaerobic organisms produce hydrogen sulphide and the strong faecal note. Nitrogen in the same material is converted to ammonia, and the ammonia rises and leaves with the air above the store.
The consequences reach beyond the store. Volume and weight of material to handle are governed by its moisture content, so a wet store costs more in transport than a dry one of the same wet weight. Runoff from a wet store carries nutrients and organic load to drainage, and a farm with a drainage problem frequently has a store problem first. Odour complaints are usually received against the store rather than against the animals, which is why the store is where attention is worth spending.
What the fermentation agent changes
Three things, with different time scales again. The rate of breakdown rises. The readily degradable fraction is consumed faster, so the material stops being an active source of odorous intermediates sooner, and the point at which the material is considered stabilised arrives earlier. Odour during storage falls, because the population producing the strongest odours is displaced by organisms working on the same material through a less offensive pathway. Moisture loss is faster, because the material is being worked through rather than sitting, and the structure that holds water in a wet pile does not form.
The honest limit is that the agent accelerates a process that was going to happen anyway. Where a store is already warm, aerated and regularly turned, the difference between accelerated and normal is a matter of days. Where a store is cold, saturated and never turned, no agent will produce a good result, because the conditions are limiting the process rather than the biology.
Application: where it is added and when
For a heap that will be turned, the agent is added at building, mixed through the material rather than applied to the surface, and the heap is sized so that it can be turned. Turning is what introduces oxygen, and an agent in a heap that is never turned is a significant cost with a limited return. For a store, the addition point depends on how the store is emptied: if material is removed from the top, dosing at the working face treats the material that is actually leaving; if it is removed from the bottom, the addition point needs to move accordingly.
Two operational points carry more weight than the product. First, the material that produces odour fastest is the freshest, so treating the incoming face rather than the whole store body is usually the effective move. Second, the moisture content at the point of application determines whether the biology can act at all. A material that is saturated has no oxygen to offer, and the agent is a seeding rather than an oxygen supply.
Where a manure treatment does not help
It does not help with a drainage problem, and it does not substitute for roof cover. Rain falling into an open store is the single largest source of avoidable odour and the largest contributor to the volume of material being handled; covering the store addresses both directly and costs less than treating the consequences. It also does not remove the need for a covered, impermeable area from which clean water cannot enter, because an agent working in a store that receives surface water is working against the inflow.
Where a farm has an existing digestor, the question is different. Material going to a digester is already under active anaerobic digestion, and the objective becomes digestion performance rather than storage odour. A different product is called for there, and it is worth saying that a storage product is not the right specification for a digester feed.
What to measure to know whether it worked
Three measurements, and all three are straightforward. Odour intensity at the store boundary, on a scale anyone can apply consistently, recorded at the same time of day and preferably at the point in the emptying cycle that has historically been the worst. Moisture content of the material leaving the store, because that is what sets the transport cost. And the time to stability, meaning how long until the material stops generating odour when it is moved.
The comparison that produces a defensible conclusion is two comparable stores, treated and untreated, over a full cycle including emptying. Odour perception is unreliable on its own because operators adapt to a persistent smell, which is why the subjective score should be taken by someone who has not worked in the barn daily, or why the readings should be supported by an instrument. We supply the agent, the application guidance for your store geometry and the trial design, and we review the results afterwards. We do not quote a percentage reduction for a store we have not seen.
Related research
The microbiology behind manure fermentation is not only our internal know-how. In a peer-reviewed study co-authored with the Ningxia Academy of Agricultural and Forestry Sciences and Ningxia University, a combined Aspergillus oryzae and Bacillus subtilis inoculant was shown to accelerate the maturation of beef cattle manure compost and suppress pathogenic microorganisms during a 40-day windrow process. Read the research summary ›
Frequently asked questions
- Does a manure fermentation agent replace covering the store?
- No, and the order matters. Covering the store addresses both the odour entering from above and the volume of material you have to handle, and it costs less than treating the consequences. A treatment agent works on the material already in the store; rain falling into an open store continues to add odour and volume regardless of what has been added to it.
- How is a manure fermentation agent applied?
- Mixed through the material rather than applied to the surface, at building for a heap that will be turned, and at the working face for a store emptied from the top. The point of addition should follow the point of removal, because treating the material that is actually leaving is more effective than treating the whole body of the store.
- Does it work in a store that is never turned?
- The effect is limited. The agent accelerates a process that requires oxygen, and in a saturated, never-turned store the conditions are limiting the biology rather than the product. The same is true of a cold store where the material never reaches a working temperature. Where those conditions cannot be changed, the honest answer is that the treatment will not deliver what a turned and aerated store would.
- Can I use a storage product for material going to a digester?
- Not without checking. Material going to a digester is already under active anaerobic digestion, and the objective becomes digestion performance rather than storage odour, which is a different specification. Tell us where the material is going and we will tell you whether our product is appropriate or whether you need a digester-feed product instead.