What do modern-day combined harvesters and Diplodocus have in common? One answer, it seems, could be their significant steps on the ground. A new study led by researchers from Sweden and Switzerland found that the weight of farm equipment today is closer to that of any of the largest animals ever to roam the Earth — the sauropods.
Described as a large, friendly “veggiesaurus” in the movie “Jurassic Park,” the sauropods were the enormous dinosaurs. The heaviest ones were thought to weigh 60 tons — the equivalent of a fully-loaded harvester. Tractors and other farm equipment have increased dramatically in the last 60 years as advanced agriculture has become more common. The compacting machine is about ten times heavier today than in the 1960s.
The weight of animals or machinery is significant because the soil can withstand a lot of pressure before hardening. They may not look at it, but the ground is a living system of delicate structures — pits and pathways that allow air to circulate and water to reach the roots of plants and other living things. Tires, animal hooves, and human feet all squeeze, rubbing pores on the surface and the depth.
Soil compaction can interrupt crop growth and harvest and increase the risk of flooding as water seeps out of the soil and reaches the water very quickly. Scientists who took part in the new study looked at the cohesiveness of these large-scale farming machines and compared them with sauropods that lived more than 66 million years ago. They find that they are both guilty of serious wrongdoing.
Under pressure
Studies show that as the weight of farm equipment increases and the size of the balloon tires, the area where the vehicle meets the ground is adjusted to reduce excess pressure and help prevent drowning. Animals seem to have evolved in the same way — by increasing the size of the foot by weight to avoid drowning.
Overall, the pressure on the surface has not changed as farm machinery grows heavier. But the authors suggest that pressure on the ground continues to rise underground and penetrates deeper as cars (or animals) become more complex. Today, farm equipment (and sauropods of the past) are so heavy that the soil is unusually dense under the first 20 cm, where it can be plowed. Apart from limiting how deep plant roots can grow to absorb water and nutrients from the soil, this can create poor oxygen levels in plants or organisms that share the Earth.
