While completing his Nuffield Scholarship, Stuart Oates founded the Fossil Free Farm project, born of his belief that removing fossil fuels from farming is essential for future sustainability.

Based at Rosuick Farm near Helston in Cornwall, he and his brother Dave are involved in various trials with the hope of finding a fossil fuel-free farming future.

See also: How a Lincs farm dries grain cheaply without fossil fuels

These trials include using locally grown seaweed as a biostimulant and source of nutrients, which could potentially replace artificial fertiliser and agroforestry that captures carbon.

A further trial is looking at replacing plastic twine for round bales with a natural fibre known as sisal.

Seaweed

The Oates have been involved in an Innovative Farmers trial using seaweed as a biostimulant.

“We rent a barn to the Cornish Seaweed Co, and I wanted to integrate the business further into the farm, as when I was younger, we used to spread calcified seaweed on the farm,” says Dave.

“So we came up with the idea of using seaweed as a biostimulant.”

Partnering with Innovative Farmers and the Farm Carbon Toolkit for the project, the aim was to find some tangible benefits of seaweed.

“An important part of this work was self-sufficiency in nutrients and local provenance,” explains Hannah Jones, farm carbon and soils adviser at the Farm Carbon Toolkit.

The seaweed is grown locally at Porthallow, and once harvested, mixed into a brew.

“We put 300kg of seaweed in an IBC, which we filled with water, added some bokashi (a microbiome that ferments the seaweed) and 20kg of molasses,” explains Tim Van Berkel, managing director at the Cornish Seaweed Co.

In the trial, the brew was applied as a seed treatment to wheat and pea wholecrop seeds and then drilled in four plots.

“I had long plans for establishment counts throughout the season, but I had all the results I needed within 10 days of the seeds coming up,” says Hannah.

“The rhizosphere was significantly different; the crops had significantly longer roots and more roots. I would like to assess the impact of disease, but at the moment there is no disease,” she added.

“The theory is that if the crop has optimal nutrition, its defence will be better.”

In the longer term, assessments will be made on crop yields and protein as well as disease, but overall, the goal is to reduce reliance on artificial inputs, therefore reducing fossil fuel use.

“This could potentially replace artificial fertiliser; we can produce it cheaply, and can put it on at all different stages,” says Dave.

“It’s not waiting for rain like nitrogen, it’s fully flexible, and doing so much more than just nitrogen, potassium and phosphate – the bottom line will be better.”

Agroforestry

The second project is agroforestry, which regenerates soil while complementing their mixed system and providing carbon capture.

Integrating trees into arable systems are also said to improve pest and disease control, by providing habitats for beneficial predators, as well as reduce soil degradation.

“The key for me is that I wasn’t taking land out of production; in a mixed system we can graze around the tree bases,” explains Dave.

Stuart Oates © Ruth Wills

Dave received a Countryside Stewardship grant to plant the trees and received maintenance payments to help them get established. He also received support from Forest for Cornwall.

“There is an array of business opportunities for future generations on the farm because I have put in this asset,” says Dave.

“But because there’s no land use change, in 10 or 20 years, if I want to get rid of them and completely change our system, I can. Trees are as permanent as you want them to be.”

However, it is important to note that thresholds were introduced by the government, which say if planting more than 100 trees per hectare, which have the potential to cover 20% of that hectare, the land use is changed to woodland.

“When they are classed as woodland, they become legally protected and permanent,” explains Joe Harris, project officer at Forest for Cornwall.

“Most agroforestry systems are designed to avoid agricultural land becoming woodland. It’s a nice rebuttal to the criticism we have heard that tree planting is a bad thing because it takes land out of food production,” he said.

“But agroforestry systems are designed to increase the volume of food coming out of farms in terms of alternative produce and building resilience.”

Dave planted as many different types of trees as possible, as a way of future-proofing his system – as the more diversity, the more resilience to future problems like lack of water or extreme heat.

The cattle and sheep rotationally graze around the trees with the use of electric fencing, and the land itself is in a rotation with arable crops.

“We have a wholecrop pea and barley mix which is undersown with a herbal ley, which is how we reseed all of our arable land. It will stay in a herbal ley for three to five years before returning back to arable,” says Dave.

“If we’re ploughing, we can move the fences right up to the trees, and work between half a metre to a metre away from the base of the tree.

“If we’re doing min till, then I would still put a subsoiler through for root stratification.”

Root stratification or root pruning stops the roots from spreading too much, so that when passing over with a plough or a tillage machine, there aren’t lumps of roots coming up.

“If we prune them once every three to five years – which fits in with our rotation – it will prune the roots in the top 8in of soil, the roots will still go out to 3m, but they will be below the depth of the tillage.”

He hopes this will future proof the fields and not interfere with any future ploughing.

Dave Oates © Ruth Wills

“I’m trying to plough less, but I did trials with a PhD student a few years ago in which we took six arable fields – ploughed half and min-tilled half – and the yield was significantly more on the ploughed,” he says.

“The biggest factor is that we undersow all our cereals, and by ploughing, this gives the cleanest seed-bed for the establishment of the herbal ley.

“It means that the ley lasts an extra two years before losing the key species, so it offsets any carbon emissions by having a healthy soil and microbiome.”

When it came to the design of his agroforestry, he allowed for space between the tree alleys to allow for machinery.

“Some, but not all, are 24m apart, as in some Cornish fields it is not practical. We have a range of machinery widths on the farm, so spacing wasn’t too much of an issue.”

The brothers are clearly passionate about farming sustainably for the future. “We’re not fossil free, none of us are, and we won’t be for a long time but what little things we can do and change can make an impact,” says Stuart.

“The small things make a really important impact, that’s not just the environment, but as we experience change, it’s becoming economically sensible.”  

Stuart and Dave Oates, Hannah Jones and Tim Van Berkel were speaking at a recent Innovative Farmers Fossil Free Farming Day event