A real electric tractor, weighed exactly
A real electric tractor already for sale, the Solectrac e25, built in California, weighs 1,445 kilograms in total. Its battery alone weighs 175 kilograms, about 12% of the whole machine, a figure MAOWCE calculated by dividing the 2 numbers the manufacturer states. That extra mass matters because of what decades of soil science say happens as farm machines get heavier.
A controlled test drove 3 tractors over the same ground
A separate, controlled field study drove 3 real tractors over identical ground to isolate the effect of weight from everything else. The heaviest machine, a four wheel drive diesel tractor weighing about 5,900 kilograms, caused significantly more soil sinkage and compaction than the 2 lighter machines, a two wheel drive diesel tractor, the John Deere JD1840, at about 2,800 kilograms, and a tracked tractor at about 4,500 kilograms, which did not differ from each other by a significant amount. The Solectrac e25 was not part of that test, but at 1,445 kilograms it weighs less than every machine in it, including the 2 that caused the least damage.
The Solectrac e25 figure comes from source 1. The other 3 tractors are from a separate controlled study, source 2, that did not test the e25 itself and did not measure its effect on soil. The tracked tractor and the 4 wheel drive diesel tractor are named only by drive type here, not by model number, because their model numbers carry a hyphen that the copy rules do not allow.
Show the numbers
| Solectrac e25 | 1,445 |
| John Deere JD1840 2 wheel drive diesel | 2,800 |
| A tracked tractor in the study | 4,500 |
| A 4 wheel drive diesel tractor | 5,900 |
Weight now reaches deeper into the soil than it used to
A landmark soil mechanics paper explains why weight is the number that matters. Above a stress of about 50 kilopascals, moist soil in temperate regions suffers chronic compaction, internal deformation that does not heal on its own. Farm machinery has climbed far past the weight it carried when that kind of damage was rare.
The total weight of laden combine harvesters has increased nearly 10 fold, from around 4,000 kilograms in 1958 to about 36,000 kilograms in 2020.
Thomas Keller and Dani Or, soil scientist and environmental scientist. Source 3.
Yet the same paper finds that surface contact stress across farm machinery, trucks and even loads carried by animals has stayed roughly the same, around 230 kilopascals, even as total vehicle weight climbed, because manufacturers spread the extra weight over wider tires and more axles. The heavier machine now pushes that same pressure deeper into the ground, because there is more total weight behind it.
The source states the front axle load figures as covering a period comparable to the combine harvester years, not the identical years 1958 and 2020, so those 2 bars are labelled decades ago and today rather than given specific years.
Show the numbers
| Combine harvester in 1958 | 4,000 |
| Combine harvester in 2020 | 36,000 |
| Front axle load decades ago | 1,500 |
| Front axle load today | 12,500 |
What extra weight costs in the field, measured in yield
A separate controlled trial puts a number on what that compaction costs a farmer. Researchers drove a 60 kilowatt wheel loader, carrying an axle load of 3,160 kilograms and pressing down at 77.5 kilopascals, over a maize field either 2 or 6 times, then compared the harvest with an untrafficked control. Yield fell 7.58% after 2 passes and 15.50% after 6, against that control.
The 0 passes bar is the untrafficked control the study measured against. The source states the other 2 figures as percent reductions from that control, not as separately measured values in their own right.
Show the numbers
| 0 passes | 0 |
| 2 passes | 7.58 |
| 6 passes | 15.50 |
Lighter tracked machinery used in wet paddy fields presses on soil at about 10 to 20 kilopascals, versus 30 to 50 kilopascals for wheeled tillage machinery in the same wet fields, and cuts ruts to under 10 centimeters instead of up to 20, according to a separate review of chassis engineering for farm machinery. None of that changes what the Solectrac battery weighs. It changes what a farmer can do to offset it, by choosing tires, axles or tracks that spread the same weight over more ground.
What this article leaves out
This article leaves out a diesel savings figure for the electric side of the tradeoff. Every manufacturer page that might state one returned an error when checked in this research, and no peer reviewed paper in this set gives one either. What runs here is the comparison these 5 sources actually support, a real battery weight set against real soil science, not a fuel saving claimed alongside it elsewhere.