Soil, farm equipment, and dinosaurs

Soil, farm equipment, and dinosaurs
May 30, 2022

New study states that heavy farm equipment is responsible for soil compaction at depths below tillage levels affecting crop growth.

By Andrew Joseph,; Image by Frank P. from Pixabay

While most dinosaurs were the size of chickens—their size belies the sexiness of it at museums, hence you don’t see them being represented—many were as large as a tank and just as heavy.

For the sauropods—the heavy cow-like dinos that spent its existence eating vegetation and avoiding predators—they were even bigger.

For fans of the Jurassic Park movies (based on a pair of books written by the late Michael Crichton), they were the first creatures we spied in the very first movie, munching leaves from the tops of trees—up on its hind legs to reach the tenderest greens.

Whether it’s the 26-ton Apatosaurus, the 33.6-ton Brontosaurus, or the real heavyweight Argentinosaurus at 85 tons, there’s no questioning that when they moved, the earth shook, and things got trampled.

It’s that trampling due to excess weight that has some in the ag community concerned.

According to a recent study in the May 24, 2022 edition of PNAS (Proceedings of the National Academy of Sciences) researchers Thomas Keller (Department of Soil & Environment, Swedish University of Agricultural Sciences) and Dani Or (Department of Environmental Systems Science, Swiss Federal Institute of Technology in Zürich), farm equipment has become so heavy—reaching the weight levels of the largest sauropods—that it is causing subsoil compaction in root zones below tillage depths that affect soil functionality.

It's true that our tractors and combines have become bigger, just as there is no denying that the mechanization of farming has revolutionized farmer’s crop yield efficiency. But, as the study points out, a higher capacity has resulted in heavier farm vehicles.

A laden combine harvester in 1958 weighed 4.4 tons, while its 2020 counterpart can weigh just under 40 tons. That’s almost 10x heavier in the evolution of the combine harvester.

The farm machinery’s weight increase over the years is the result of increased power and capacity combined with wider cutter boards and a larger grain tank capacity, all of which provides an improved harvest efficiency.

It should also be pointed out that tires for the farm equipment have become larger, too, in both volume and width. With greater flexibility, it allows for a lower tire inflation pressure depending on the load for floatation and traction and to prevent the whole kit and kaboodle from sinking into the soil.

It’s not a unique development, according to the researchers. They point to animals such as camels that must “float” over soft ground (the sand), and have evolved with a relatively high footprint contact area.

The study states that “modern agricultural machinery belongs to the floating category, with a high contact area”—just like the sauropods.

We know that farmers understand that soils are complex ecosystems consisting of fragile structures like pores and pathways that allow water to reach roots and air to circulate and allow beneficial organisms to propagate. With every step we take on our soil, we compact it just a little bit.

However, the researchers state that with the heavy equipment we have today, soil compaction isn’t just at the top, it’s down deep within the subsoil.

In fact, soil compaction is occurring at 20 centimeters (7.9 inches)—below where we generally till.

That’s important because the compacted depth restricts where a plant’s roots can grow as it seeks water and deeper-soil nutrients. The compaction also reduces the amount of oxygen able to permeate the soil, which adversely affects organisms in the soil (and the crops, too).

However, it’s true that farmers will add fertilizers at a depth where a plant’s roots systems can feed from—uh, how much is fertilizer these days?

The weight conundrum leads to a perplexing problem, according to the researchers.

The sauropods weighed so much and trampled plants and compacted the soil and subsoils that allowed its own food sources to grow.

Although we aren’t at the tipping point where our farm equipment is rendering crop yield in a negative manner, the researchers believe that design changes to farm machinery will help maintain soil structure or have humanity risk going the way of the dinosaurs.

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