Scottish farmers ditch heavy tractors in bid to tackle flooding

The average weight of a tractor in the 1970s was 1.5 tonnes, whereas by 2024, it has increased to over 11 tonnes, according to NatureScot, the Scottish Government's environmental advisory body.  

In March 2015, the UK Government announced an increase in weight for tractors and trailers. The combination of tractor and agricultural trailer was increased from 24.39 tonnes to 31 tonnes.  

Bigger equipment has its benefits as it allows better harvest efficiency, but heavy machinery crushes the soil and makes it denser, increasing the risk of flooding. Heavy Weight machinery impacts biodiversity (Image: Getty Images/iStockphoto)

The water cycle at an impasse   

As you drive through the countryside, it's common to see fields flooded, to the point where it almost feels like a normal occurrence.

In healthy soil, water should either evaporate into the air or be absorbed into the ground, where it will nourish a rich ecosystem full of bugs, fungi and animals such as moles. 

However, 21st-century farming has created a non-sustainable way to use the field. Due to the use of heavy machinery throughout the years, the soil will become more compact, allowing less water to enter the ground.   

Flat fields become then flooded during heavy rainfall with no escape route, while steep fields experience water runoff.   

During hot summer weather, the compacted soil overheats due to the lack of plants and roots to help regulate the temperature, increasing the risk of fire.  

Ruth Ashton-Shaw, a farmer from Dumfries and Galloway, who is a member of the Nature Friendly Farming Network (NFFN), observed these issues in her fields and shifted to more sustainable farming practices.  

Dumfries and Galloway NFFN farmer Ruth Ashton-Shaw (Image: Joanne Coates for the NFFN)She first noticed a big amount of water draining through her farm.   

“The problem with this water flow is obviously that it just strips the nutrients out of the soil and takes it all down to the river, where it causes flooding and pollution,” Ruth explained.   

She then started by downsizing her farming equipment and rotating grazing livestock such as her sheep, cows, and pigs. She quickly noticed the return of plants that help with soil regeneration.  

She explained that the diversity of plants is one of the main elements to look for as diversity in types of plants means diverse roots which is a good indicator of soil health. Other plants are needed "not just grasses with shallow roots".  

Ruth said that their way of managing the farm is "gentle and very light" as they are "avoiding, at all costs, any compaction" of the soil.  

READ MORE: Looking to what the future holds for Scottish farming

Ruth slowly realised her soil was not in great health when they started doing organic.   

“It was almost a Eureka moment where we realized that we needed to stop focusing on the stock and look right at the source."

“Everything starts with the soil.  

“The soil is responsible for the nutrition that's available in the grass. It's responsible for how well we can exist during the winter, whether we flood, whether we freeze, drought, all the way down to when the grass starts growing in spring.”  

After taking care of her soil health, she noticed that everything became easier on the farm.  

When Ruth began downsizing her equipment, she realised that farmers have a tendency to prioritise larger farming machinery, believing that bigger was better.  

“I think there's this huge push for everything to be bigger, and the bigger it is, the better it is.”  

“When you say to people, I'm looking for something small. It's quite niche, they almost laugh at you, like you're not a real farmer.”  

Tractors compared to dinosaurs?  

Thomas Keller, a professor at the Swedish University of Agricultural Sciences, and his colleague Dani Or compared the weight of farming machinery to dinosaurs, more precisely Sauropods.   

According to their study, the heaviest Sauropods, with their long neck and four pillar-like legs, weighed between 60,000kg and 80,000kg. As a comparison, they show that a modern sugar beet harvester fully loaded weighs 60,000 kg.

Harvest in progress (Image: Martini)

“It is interesting and perplexing that some of these were heavier than today's agricultural machinery and hence induced larger stresses to the soil, which made us speculate about how these giants could walk through the landscape and whether they had to adjust their behaviour,” said Keller.   

READ MORE: Storm Babet: Horses stranded in flooded field are rescued

He goes on to explain that the increase in weight in the 21st century is driven by a greater need for efficiency and capacity. 

“Harvesters also have much higher capacity (larger grain tanks, wider cutter boards), so it is much faster to harvest one hectare than it was some decades ago, but the capacity increases the weight.”  

Keller does not believe this system is sustainable in the long term.  

“The heavy weights, heavy wheel loads, is particularly a problem for what we call the subsoil, which is the deeper rooting zone, soil about 30 to 100 cm depth.”   

He explained that the compaction of the soil at this level is "invisible" and will take years to decades to recover.   

He considered various solutions for creating a more sustainable system. To reduce compaction, heavy machinery could be restricted to "tram lines" or "controlled traffic farming," meaning all vehicles would need to follow the same paths when working the field.  

“Autonomous vehicles offer interesting perspectives because these could be small but many,” said Keller.   

However, he explained that this poses a problem for the harvest and the transport of tonnes of grains.   

“Smaller machinery otherwise would mean higher costs for producing food. Are we willing to pay for that?”