Farm vehicles are now heavier than most dinosaurs: Why that's a problem

What are the similarities between a combine harvester and a Diplodocus? One answer may be their footprints on the soil. A new study led by researchers from Sweden and Switzerland has found that the weight of farming machinery is approaching that of the sauropods.

sauropods were the biggest of the dinosaurs and were depicted in the movie as the giant, friendly Veggiesaurus. The weight of a fully laden combine harvester was thought to be around 60 metric tons. Over the past 60 years, farm machinery has grown heavier as intensive, large-scale agriculture has become widespread. A combine harvester is ten times heavier than it was in the 1960s.

The weight of machines and animals affects the strength of soils. They don't look at it, but soils are composed of fragile structures that allow air and water to pass through them. The pressure applied by tires, animal hooves and human feet squashes the pores, not just at the surface but deeper down as well.

As water runs off the land and reaches waterways more quickly, it can cut plant growth and harvests, and increase the risk of floods. The sauropods lived over 66 million years ago, so the scientists compared the amount of compaction caused by these giant farming machines to the sauropods. Both of them were big culprits of compaction.

Under pressure.

As the weight of farm machinery has grown, tire sizes have ballooned, adjusting the area of contact between the vehicle and the soil to reduce the pressure on the surface and help avoid sinking. Increasing foot size with weight helped animals avoid sinking into the soil.

As farm machinery has gained weight, the pressure at the soil surface has remained constant. The authors suggest that the stresses on the soil continue to increase as vehicles get heavier. The soil below the first 20 cm is irreparably compact due to the heavy farm machinery. Low-oxygen conditions that are not good for plants or the organisms they share the soil with can be created by restricting how deep the roots of crops can grow.

Where did the dinosaurs go for dinner?

As the researchers call it, this creates a sauropod paradox. The dinosaurs and the loads they transmitted through their feet would have caused significant damage to the soils wherever they lived, potentially destroying the ability to support the plants and ecosystems they would have relied on as their food source.

The image of sauropods roaming freely as depicted in the movie is unlikely as they would have had an unsustainable influence on their environment. How did they survive?

The scientists behind the study theorize that they may have kept to well-trodden paths, limiting their impact while browsing the canopy with their long necks. It's not clear how a sauropod could live in equilibrium with the soil.

It's big food for thought.

There is a pressing dilemma of how to reconcile soil compaction by farming vehicles with sustainable food production today. The risk of soil compaction varies with the type of machinery and the way it is used, as well as the type of soil.

The study estimates that 20% of croplands globally are at high risk of losing productivity because of subsoil compaction by modern agricultural vehicles, with the highest risks in Europe and North America where there are more large farms using the largest machines. In arable landscapes, this is an issue, but the problem also extends to grassland, where the movement of construction vehicles on green space is not well controlled, and urban landscapes, where the movement of construction vehicles on green space is not well controlled.

Alterations to machinery are called for to help maintain the soil. We suggest a different option. We could reduce the impact on the soil by growing food on smaller parcels of land in high-risk zones and using smaller machines. It makes sense to break up monoculture landscapes. Wildflower field margins, hedgerows and trees can help sequester carbon, manage water quality and support biodiversity.

The soil can only tolerate so much pressure. Humans have to act to reduce pressures on soils or we will go the way of the dinosaurs.

More information: Thomas Keller et al, Farm vehicles approaching weights of sauropods exceed safe mechanical limits for soil functioning, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2117699119 Journal information: Proceedings of the National Academy of Sciences

This article is free to use under a Creative Commons license. The original article is worth a read.

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