Capturing fugitive gas from slurry lagoons on a farm can cut energy costs and help the environment by reducing the amount of greenhouse gases and ammonia that are released into the air.
Mark Clayton, the chief technology officer at Qube Renewables, said that the company’s removable lagoon cover, which works as an aerobic digester, was giving dairy producers good returns. The product floats on lagoons, open-top tanks, and settling ponds to collect biogas, which is made up of methane and carbon dioxide. It also keeps tanks and lagoons from filling up with too much rainwater.
Clayton said that at the bottom of the lagoon, a gas-mixing system is put in place to stir up the feedstock and help the natural processes of anaerobic digestion work better. The captured methane and CO2 are then used to make heat and electricity on-site.
He said that a typical 92,460 gallon/3,500 cubic metre 3535m lagoon, which is emptied once a year, gives off about 59,000 cubic metres of biogas every year. Farmers could make up to £35,x`000 (about $40,000) a year by collecting gas from a lagoon. This would cut their energy bills by a lot and give them a return on their investment in about 3–4 years.x1
Even though the UK government gives grants for lagoon covers, Clayton said he didn’t think the government took this technology seriously enough. He said that methane traps more than 20 times as much heat in the atmosphere as carbon dioxide.
Boosting slurry value
With fertiliser prices going up and worries about its supply and ammonia emissions from slurry, farmers were told to look into how bacteria and enzymes can help producers get the most out of their slurry.
Liz Russell, the founder and managing director of EnviroSystems, talked about a recent study that showed slurry treated with a mix of beneficial bacteria and enzymes had a lot more nutrients, worth about 20% more, than slurry that hadn’t been treated.
NRM labs looked at slurry from 250 farms over the course of 4 years and found that treated slurry had 27% more nitrogen, 45% more phosphorus, and 16% more potassium than untreated slurry.
“Producers had to sell 1,700 litres of milk in August to pay for one tonne of nitrogen fertiliser. This is 800 litres more than they had to sell between January 2019 and June 2021. So, the vaccine can make a big difference in terms of money.
“The inoculant also makes the slurry more uniform and easier to spread, which makes it easier to apply nutrients evenly. And the slurry needs less constant stirring, which saves time, fuel, and machine wear and tear. This, of course, helps reduce the carbon footprint,” she said.
Based on figures from the Agriculture and Horticulture Development Board for fertiliser, she said that farmers could make £3.29 (US$3.72) more per cubic metre of slurry by the end of August if they used the inoculant. This is especially helpful since the cost of treating slurry is going up.
Mark Robinson, who farms in Lancashire, said he had been using the inoculant for 20 years, when he started as a trial farm. His most recent slurry analysis showed that it was 7.5% dry matter, which makes it easy to pump. He uses it to help grass, wheat, and maize grow better. You can use 12 cubic metres of treated slurry instead of a 25 kg bag of ammonium nitrate fertiliser.
With 20–30% white clover, it is possible to fix 180 kg N/ha. Image: Canva
With 20–30% white clover, it is possible to fix 180 kg N/ha. Image: Canva
Dr. Henry Russell, a biochemist and the director of EnviroSystems, talked about the latest results and problems from a project to study slurry ammonia emissions. The project is funded by Defra/Innovate UK and also includes Myerscough College.
The main goal of the project is to find a biological way to deal with the slurry from dairy farms that is both cost-effective and meets the ammonia reduction goals that will go into effect in 2027.
“We want to cut down on ammonia emissions while also making slurry more uniform and giving it more nutrients. This is a very important goal because the cost of buying fertilisers is going up so fast.” This will be done with auto-dosing technology, and it will be the next generation of slurry inoculants.”
Russell said that farmers who wanted to take advantage of the grants for lagoon covers and better storage systems needed to make sure they had good mixing systems. “Make sure you have the right mixing equipment and that the right amount of ammonia is being released during spreading. A pH value of 5.5% is much better than a pH value of 7 or 8.”
Nutrition for forage crops
Lisa Hambly, head of grassland and forage agronomy at Mole Valley Farmers, said that healthy soils are the most important part of making the most of what you have because they store over 10 billion tonnes of carbon.
The following are signs of healthy soil:
- Good soil condition
- Sufficient depth
- Getting the right amount of nutrients
- Few plant disease-causing organisms and insect pests
- Good soil drainage
- A lot of organisms that are good for the environment
- Low number of weeds
- Chemicals and toxins that could hurt the crop are not used.
- Resilient to degradation
- able to withstand the weather
Hambly said that there were many ways for farmers to improve the health of their soil: “Make sure that every field has a recent soil test.” At the very least, this should include phosphate, potassium, pH, and magnesium, which is a requirement of the government’s Farming Rules for Water.”
The results can be used to make a plan for managing nutrients so that nutrients can be put where they are needed based on things like cropping and rainfall, which will reduce the need for fertiliser. Each field should be kept an eye on so that nutrients can be sent to fields with higher yields, which will respond better. There are things that can be done about poor performance on the field.
