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A new inoculant can help farmers improve slurry management – reducing the need for bought-in fertilisers. Researchers shortlisted almost 30 different strains of bugs... How inoculants can improve slurry management

A new inoculant can help farmers improve slurry management – reducing the need for bought-in fertilisers.

Researchers shortlisted almost 30 different strains of bugs and fungi to see whether they could reduce crust formation on slurry stores. To identify the best one, they then tested five of the most promising bacteria under laboratory-controlled conditions.

The best-performing micro-organisms worked most effectively by maximising complex biochemical pathways within slurry. Crust formation was reduced by 23-29% – enabling farmers to improve their on-farm waste management.

Conducted at Myerscough College, the research findings have helped redevelop two slurry innoculants: SlurryBugs and SlurryBugs Maintenance – fine-tuning the specialist bacteria and fungi to produce what is essentially an entirely new product.

Nutrient content

Scientists also observed a 10-15% increase the nitrogen, phosphate, potassium and sulphur content of treated slurry. This is because organic materials are released into the slurry when the crust is broken down.

New studies are under way to examine this further. Commercial company EnviroSystems has already undertaken specialist trials at Myerscough’s dairy farm to ensure the study is completed with reliable and accurate outcomes.

EnviroSystems head of research David Townsend said: “Trialling slurry additives on full-scale farm systems presents difficulties due to the huge volumes of slurry involved and the inability to run controls or duplicates within a controlled setting.”

Dr Townsend added: “As a result, we mimicked a slurry lagoon using 20-litre drums, which allowed us to increase our scrutiny over the experiments and the accuracy of the data we collected.”

Reliable results

The control and treated drums were dosed with the relevant additives and maintained under closely monitored conditions for three months. Each treatment was repeated four times to ensure the results were reliable.    

Reducing crust formation is becoming more critical as a government deadline approaches for farmers to cover slurry stores by 2027. Store covers are already recommended by Defra’s guide to good agricultural practice.

Covering slurry and digestate stores reduces ammonia emissions. Without a crust, stores will able to hold more slurry – helping to ensure farms have enough storage to spread slurry only when crops will use the nutrients.

Dr Townsend said: “Without farmers managing the crust, they will have no idea what is happening underneath the cover – and by the time a crust becomes noticeable, it might be too late to intervene.

He added: “By improving the nutrient value of slurry by releasing trapped nitrogen, carbon, phosphate and potassium materials into the slurry, farmers have the potential to reduce the use of synthetic fertiliser.”

Two-step process

SlurryBugs and SlurryBugs Maintenance should be applied in a two-step process. New customers and those with a crusting issue are advised to use SlurryBugs to break down any existing crust and prevent the accumulation of fibrous material.

Each 1.5kg sachet of SlurryBugs treats 500m3 of slurry. Once a homogeneous slurry has been achieved and the crust is under control, SlurryBugs Maintenance is a lower-concentration product that can help prevent further problems.

“Slurry is a valuable product, and you must make it work for you,” said Dr Townsend.

Sachets could be used over the summer to top up the bacteria content and prevent dry crusts from forming ahead of the next storage season.

“Not only have we refined our products through this rigorous testing and utilising specialist strains of bacteria, but we have also made it easier for farmers to treat their slurry and prevent any unforeseen crust crisis from occurring.”

Apply for a free year’s supply of SlurryBugs worth £1,000

Farmers can find out more about slurry inoculants by visiting the EnviroSystems stand at next month’s Dairy-Tech event.

EnviroSystems managing director Liz Russell has been at the forefront of slurry additive research. She will be at the Dairy Tech event – held on 7 February at  Stoneleigh Park, Warwickshire.

Dairy producers attending the event will be able to apply for a free year’s supply of SlurryBugs in exchange for data collection, said Ms Russell. Spaces are limited and terms and conditions apply.

The closing date for applications is 28 February 2024. For details, visit EnviroSystems on stand L2 at Dairy-Tech or email