A trial run earlier this year at Westwood Farm, Sevenoaks Weald has proved that a bacteria based slurry additive increases total N by 7% and ammonium N by 23%. This is at a time when the price of bagged fertiliser has rocketed, and is predicted to hit £400 a ton early in 2009. 

The additive, distributed by Tunbridge Wells based agricultural firm Epizym, has undergone rigorous scientific tests and informal trials in the UK and abroad in recent years. The bacteria it contains use the slurry as a food source. They break down the particles to produce a consistent and runny mix, virtually eliminating crusts. Levels of available nitrogen and phosphorous are increased and odour formation is reduced by over 50%.

Giles Dadd, FACTs registered advisor and principal agricultural consultant to Epizym explains the simple trial. “We wanted to run the test to make sure that the product was still delivering on its promises, as previous trials had shown.

“Two 25 litre plastic buckets were filled with cow slurry and some straw bedding from the passageway of the cubicle house prior to scraping out. Into one bucket an appropriate dose of rehydrated Epizym Cattle was added.”

After six weeks the buckets were visited for final analysis. “There was a big change in terms of smell in one of the tubs,” says farm owner Richard Hamlyn, owner of Westwood Farm, which has been in the family since his grandfather took it on in 1936.

Samples were taken and sent off to NRM Ltd for independent analysis.

“We were delighted to find the results fit with the trial we did in Holland some years ago, with Total N at 7% increase and ammonium N at 23%”, says Giles.

 “The financial reward for nitrogen increase was our key measure. We ignored the savings in agitation time and diesel – which are probably considerable with fuel prices escalating all the time.”

Trial assumptions were nitrogen at £1 per kg (£345 per tonne of AN), 150 cow herd producing 1700 cu. m slurry over 6 months (2,500 gallons per cow), and no spreading losses were factored in.

The full results showed:

                                                                       
In terms of value this meant:

1. 459 kgs extra worth of total N – representing £459 of added N. However, this is not all crop available but ammonium N is the key ingredient.
2. 697 kgs extra ammonium N worth £697
3. All for an outlay of £300 on Epizym.

“I’m delighted with the results and plan to trial Epizym from October,” says Richard. “We have a weeping wall based slurry system with an integrated reception pit and tin tank holding 150,000 gallons of slurry. This needs careful management and sometimes daily effort.”

“We can see that Epizym can save us money, and so we’ll trial it. I estimate the biggest savings will come from buying less bagged fertiliser and reduced labour costs. We’ll use less diesel and complaints from neighbours about smell will hopefully reduce. We’re in a rural area but have houses close by.” 

Richard’s also looking forward to seeing a difference on spreading. “We know other farmers using Epizym find their slurry is far more consistent and liquid than before. It goes on in a more uniform way, meaning less leaf contamination and a better spread of nutrients across the field.”

In addition, the resulting liquid, easy to handle organic fertiliser enables farmers to maximise capacity in their storage systems, through reducing the solid matter that remains in the store after emptying. This helps compliance with NVZ regulations during closed spreading periods. 

Epizym reduces odour formation by up to 50%. It puts floor solids into ‘suspension’ within the mix, thus removing the environment where odours are formed and stored. Indole and skatole, two of the most potent, penetrating odourisers found in animal waste, are enzymatically reduced to odourless compounds through bio-oxidation. Organic amines, which produce some of the most offensive odours, are totally destroyed in the process.