BioAg Digest-it® for Dairies
What is effluent?
Effluent is a slurry of water, manure, urine, milk and other waste collected in the wash down liquid. It is a particularly strong form of organic waste that is characterised by its high oxygen demand, high volatile solid content and high phosphorus, nitrogen and potassium levels.
Why is effluent management important?
Effluent management is a major concern on many New Zealand dairy farms due to increased herd size, intensification and environmental scrutiny and regulation. Dairy farmers have a legal obligation to contain, manage and dispose of livestock effluent within their property’s boundaries in a manner that prevents pollution of surface and ground water.
How do dairy farmers manage effluent?
On many New Zealand dairy farms, a single pond is used to capture wash down liquid. Following “settling out” over several weeks or months, liquid effluent is then discharged into a “sacrifice area” or into an irrigation pond and spread over pastures as part of the usual irrigation program. It is often ‘shandied” with incoming irrigation water. Although the volume and composition of effluent produced varies greatly according to the individual property and season, many single-pond systems are now incapable of handling the increased volumes of effluent generated.
How does an effluent pond work?
A correctly functioning effluent pond should contain high levels of oxygen and therefore aerobic bacteria that digest organic material, thereby:
- Reducing organic matter and nutrient levels
- Removing suspended solids and salts
- Creating an acceptable pH (6.8–7.5)
- Reducing odour
This process is assisted via a complex interaction of sedimentation, precipitation and mineralisation.
What are the signs of a non-functioning effluent pond?
Non-performing effluent systems are instantly recognisable by the presence of persistent surface crusting and their pervasive odour. A common symptom is the formation of a crust, whereby undigested solids form a crust up to 50 cm thick on the surface of the pond. Besides harbouring vermin, insect pests and weeds, this crust creates an anaerobic environment underneath. The depletion of oxygen in the water, combined with lack of sunlight, reduces microbial digestion. Nutrients may remain at toxic levels or settle within the sludge, where they become “locked up” in forms that are unavailable to plants. The proliferation of anaerobic bacteria can lead to an increase in hydrogen sulphide (i.e. rotten egg gas) and increased pH (i.e. alkalinity). High temperatures can also stimulate anaerobic bacteria at the bottom of the pond.
What is Digest-it® for Dairies?
BioAg Digest-it® for Dairies is a fermented microbial culture that helps to create and maintain a balanced microbial environment in effluent ponds, thereby stimulating microbial digestion of organic matter. Following an initial application to the pond, it is added in small amounts to the wash down solution each day, Digest-it® provides a rich food source for microbes as well as dormant aerobic bacteria species. Specifically, it contains a rich source of vitamins, minerals, proteins, enzymes, amino acids, carbohydrates, dormant organisms and growth promoters.
What does Digest-it® for Dairies do?
- Stimulates aerobic microbial activity in effluent ponds
- Digests suspended solids into plant-available liquid nutrients
- Reduces turbidity and increases the liquids to solids ratio
- Reduces surface crusting, solid waste and the need for desludging
- Reduces unpleasant odours
- Increases fertiliser value of effluent
- Can also be used as a silage inoculant or to reduce odours in calf bedding and herd homes
What types of effluent systems can benefit from Digest-it® for Dairies?
Digest-it® for Dairies is ideal for all types of effluent management systems, particularly:
- Non-functioning effluent ponds
- Older systems that have become overloaded by increased herd size
- Large herds or those with high effluent loads
- Or where effluent ponds are close to dwellings, neighbours or towns.
It is also suitable for use in direct application and multi-pond systems.
How can you tell if Digest-it® for Dairies is working?
Depending on the thickness of the surface crust, a number of physical and chemical changes can be observed in ponds within four to six weeks of treatment with Digest-it®. These effects vary greatly according to the individual characteristics of the pond, but include:
- Increased aerobic microbial activity
- Dissolving of the surface crust
- Reduced turbidity and increased liquids-to-solids ratio in pond due to digestion of dissolved and suspended solids
- Bubbling due to increased microbial fermentation of volatile solids and the associated formation of carbon dioxide
- Formation of “bolls”, i.e. clumps of solids released from the pond bottom
- Reduced odour, thereby providing a more pleasant environment for workers, family and neighbours
How can use of Digest-it® help to reduce fertiliser costs?
Digest-it® for Dairies helps to convert solids into “biologically-active” liquid nutrients that can be efficiently used by plants and soil microbes. Farmers can strategically utilise treated effluent as part of their pasture or crop nutrition plan to optimise plant growth, animal health and herd performance.
Can I use Digest-it® for Dairies on a certified organic farm?
Yes. Digest-it® is BioGro Permitted
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How much does it cost to use Digest-it® for Dairies?
The cost of a year-round or seasonal program using Digest-it® depends upon the pond size and herd size and volume purchased. However, as a guide, the cost of a Digest-it® program typically ranges from approximately 4.5 cents up to 10cents per head per day.
Cost offsets can be achieved via improved fertiliser value, reduced or eliminated cost of desludging and subsequent contractor spreading costs, reduced compliance cost risks, improved pasture growth and nutritive value, improved animal health off effluent paddocks.
Can Digest-it® for Dairies be used for other purposes?
BioAg Digest-it® has many other uses around the farm. It can be applied in animal bedding and herd home floors to help reduce odours. Digest-it can also be used as a composting aid, offal and waste leachate treatment and also in septic tank and grey water systems in fact in most situations involving organic matter wastes.
How much should be applied at the initial pond treatment?
Apply 20 to 60 litres of Digest-it® as a diluted spray directly to the wet areas of surface crust and flushed through pond or sump inlet drains to stimulate microbial activity. Partially fill spray tank with water. Agitate container and add required amount of Digest-it®. Fill the remainder of the spray tank with water with the agitation system engaged. Use within 48 hours of dilution.
| Pond size |
**Application rate |
| 25 x 50 x 3 metres |
20 L |
| 25 x 75 x 3 metres |
40 L |
| 40 x 100 x 3 metres |
60 L |
** Initial charge rates subject to site evaluation to consider factors of; pond size relative to herd number, inflow & outflow
placement, depth, single or multi pond systems, solids separation.
How much should be applied for ongoing treatment?
Digest-it® should be applied with the shed wash down on a daily basis to maintain a balanced and sustainable microbial population in the effluent pond. Simply pour the required amount of undiluted Digest-it® near a shed drain point ensuring the Digest-it reaches the pond or sump with the wash down water.
| Herd size |
**Application rate |
| Up to 150 cows |
1.0 L / day |
| 151–250 cows |
1.0 - 1.75 L / day |
| 251– 450 cows |
1.75 - 3.0 L / day |
| 451–650 cows |
2.5 - 4.5 L / day |
| 651–850 cows |
3.0 L - 5.5 L / day |
851–1250 cows
|
4.0 - 8.5 L / day |
**Rate variation dependant on effluent load factors e.g. pasture feed only, Pasture/feedlot, time on feedlots, herd home concentration and wintering barn operations.
How are direct discharge sumps treated?
Initially the sump needs to be charged in the same manner as a pond. The initial charge is based on the sump capacity. Thereafter the daily replenishment is based on the table above in most circumstances and also how much land effluent is spread on per year and the frequency that the same area has effluent applied. This may result in an adjustment to the daily rate to ensure that the soil receiving the treated effluent can utilise the nutrients to the best advantage for the pasture.
How soon can we graze following Digest-it® treated effluent?
Cows may graze treated paddocks after 24-48 hours.
N.B. Longer withholding periods due to other farm practices may be required.
How should Digest-it® be stored on farm?
Containers should be stored out of sunlight and below 30°C. Note that it has a storage life of 12 months. Customers should only order what they can use in a six-month period to ensure they have fully effective product.
What size containers is Digest-it® supplied in?
Digest-it® is available in 5L, 20L, 60L, 200L and 1000L containers. Pricing varies accordingly.
Where can I purchase Digest-it®?
Please refer to our contact details for your nearest agent or call BioAg Head Office.
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