Digestate Project at Newton Farm

By Menna Williams, South Wales Red Meat Technical Officer

The digestate project at Newton Farm, Brecon has now completed, and during an on farm meeting the results were disseminated.

Digestate is a by-product of anaerobic digestion, the food-based digestate for the project came from Bryn Pica AD plant, 4 miles from Aberdare, South Wales. The nutrient content of the digestate worked out at 111:20:41, and the product was applied to 0.5h plots via a splash-plate, trailing shoe and disc injector at a rate of 9.11t/acre. We matched a compound fertiliser to the digestate which was applied at a rate of 9t/acre (important to note the fertiliser plot received 1.11t/acre less nutrients.)

Grass growth was recorded every week for 7 weeks and the results are shown below- 

The difference in cost between fertiliser and digestate was substantial-

(Using this year’s average fertiliser prices)

Fertiliser costs (9.11t/acre)-

N= 111units @28.5p/unit= £31.64

P= 20units @ 27p/unit= £5.40

K= 41 units @ 20.5p/unit= £8.40

Total cost of compound fertiliser= £45.40 of nutrients/acre (not including spreading cost)

Digestate cost- £2/tonne spread @ 9.11t/acre = £18 of nutrients/acre

Digestate has been proven to be a viable option for farmers within the catchment area, not only being much more economical compared to compound fertiliser but also helps restore the natural recycling of nutrients and  also recycles scarce nutrients, such as phosphorous.

Secondly, by using digestate instead of some synthetic fertilisers derived from natural gas, we can save energy, cut consumption of fossil fuels and reduce our carbon footprint.

It is very important to remember that we need to use this product sensibly and sustainably due to its high nutrient content and Charlie Morgan highlighted this during the meeting ‘if we were to use this product day in day out on grazing fields our phosphate and potash would go over required indexes, therefore there is an absolute essential importance to be doing soil tests and discussing the amount of digestate we apply’.