The addition of a liquid slurry inoculant during the winter has delivered increased total nitrogen and a reduction in solid crusting during application in the following spring.

Although slurry inoculants aren’t new, Digest-It, from Origin Fertilisers, is a liquid microbial product aimed at Scottish farmers looking to increase the nutrient recovery and minimise environmental losses through ammonia emissions.

Leah Williamson, nutrition agronomist at Origin, covering North-west England, said using treated slurry enabled farmers to have a better chance of increasing yield and quality in their crops through improving the total nitrogen content of an existing product. This meant they were extracting more nutrient value from what they already had.

Digest-It differs from other similar products in that the liquid inoculant provides a food source from microbes and dormant aerobic bacteria that can feed on and break down the organic matter in slurry. The bacteria within the slurry use the ammonia gas as a source of nitrogen to grow and turn it into microbial nitrogen, that is said to increase the total nitrogen content.

Research across 15 UK dairy farms showed a 33% increase in total nitrogen, and a slurry additive trial in 2011 by independent dairy consultants, Kingshay, found it increased the total nitrogen within cattle slurry more than other products on the market.

Slurry inoculants have tended to come in powder form, so require an element of premixing before applying to the lagoon or store, however, as it is a live bacterial liquid and comes in 20-litre cans, it can be poured in at an application rate of one-litre to treat 22,500m3 of slurry. It requires a minimum of eight weeks in the slurry prior to application, so needs to be applied in the winter for maximum efficacy.

Alongside the nitrogen increase, it is the practical efficiencies that will be noticed daily by users. Reduced agitation, or mixing has been a significant advantage due to less crusting on the surface of the store, while the thinner consistency has practical advantages during spreading.

“It is much easier to pump, with less impact on wearing machinery parts and helps to lower fuel use, while the reduction in ammonia contributes to less smell when spreading,” explained Miss Williamson.

Scottish farmers deterred from a financial perspective should also consider the wider environmental benefits of treated slurry. Comparative trials on worm counts have shown increased activity and numbers following application. Spot counts on fields that received a treated slurry application revealed worm counts some 1,000,000 worms higher per ha than the untreated slurry area.

Cumbrian farmer, Robert Barrow, had been trialling the product over the past 12 months in one of his three slurry stores and, following applications to his fields this year, had seen both environmental and handling benefits to his slurry.

Slurry is an essential resource for Mr Barrow, who milks 200 Holsteins and runs a 200-strong flock of Lleyn ewes and lambs. Milk is sold to First Milk on the Nestle contract, and he is part of its regenerative farming initiative. Slurry, which was treated in October with the inoculant, was applied to grassland in spring ahead of first cut, to assess the outcome.

“We only applied Digest-It to one of the lagoons, which allowed us to split a field in half and spread the individual lagoons via separate tankers to see if there was any difference in the slurry. It was obvious after application, as we could see to the line where the two products met. The treated area had a much taller sward and was a lusher green colour.”

Other benefits seen by him included the treated slurry being easier to pump and spread due to the thinner consistency and reduced solid matter. This uniformity also has increased the rate of soil absorption, he said.

“The treated slurry is easier to apply and is more like a milkshake consistency, which meant that it worked into the soil quicker than our normal slurry, helping to reduce losses to the environment by not sitting on top for extended periods. It also means we can graze sooner as there is no fibre laid on top of the grass and a reduced smell during and after application, too.

“We quickly realised that the treated lagoon didn’t require stirring to the extent we had been used to. We only had to stir for 10 minutes as there are fewer solid parts to mix, whereas we were used to stirring for up to half a day beforehand,” he added.

Currently the farm applies slurry via tankers, but he said the treatment will help move to a dribble bar application.