The first mobile steam engines for use on the farm were built in the 1860s.
In Britain, they weren't a huge success due to soils being too heavy and wet. The power-to-weight ratio worked against them.
Steam-powered tractors were more successful in the United States on firmer, drier soils.
The game-changer was the manufacture in the early 20th century of tractors that ran on liquid fuels made from oil (kerosene, diesel, petrol).
These fuels packed a greater energy punch than coal. And they allowed tractors to be built lighter.
Tractors and other farm machinery took off in the US, where there was an abundance of oil and flat agricultural land.
In New Zealand, tractors were common on farms in the 1930s and ubiquitous after World War II.
In every country that went down the industrial route, increased mechanisation on the farm went hand in hand with bigger farms.
To get the most out of expensive farming machinery, you needed a decent amount of land to spread the capital cost.
Small, labour-intensive (human and animal) farms couldn't compete with large-scale industrial farming methods when it came to generating capital or producing for export.
Cheap oil was the ingredient that greased the whole process. Used on the farm to get food to markets nationally and internationally, and to produce chemical fertilisers.
A few years ago, I spent a weekend on a farm in Canterbury. The farmer's main crop was grass seed, sold in New Zealand but mostly exported. He also grew crops to sell to other farmers to feed their cows, and he leased some land for grazing.
What amazed me was the amount of machinery on the farm. Multiple tractors, all huge. Trucks of various sizes. Harvesters and other unidentifiable, to me, pieces of machinery towed behind tractors.
Then there were giant water irrigators that bestrode the land, also moved by tractor.
He had one part-time farmhand. Otherwise, nearly all the work was done by him.
By his own admission, work mostly consisted of sitting in a tractor cab, sometimes for 10 hours a day.
I thought it was sad.
I don't think the farmer was that happy about it either, but he was doing what he had to do to compete and remain profitable.
I hadn't seen so much farm machinery in one place again until I witnessed last week the enormous tractors rolling through Whangārei for the "Howl" protest. I was similarly fascinated by such an impressive mobilisation of machinery.
At a Howl protest in Blenheim, Judith Collins apparently said: "I'd like to see them try to make an electric version of that", referring to a large tractor that had just driven past.
She had a point.
While an electric tractor can be built, the power-to-weight ratio won't be as good as a diesel or petrol-fuelled tractor. The recharging frequency will be problematic also.
Like the ancient steam-powered one, an electric tractor will prove unworkable on some terrains and soils, and for some essential farming tasks.
Biofuels made from plant material are the more likely medium-term energy source for farms. Yet, it's hard to imagine how New Zealand could produce enough at a cost comparable to the price of diesel now.
That's the problem, alternative energy sources will contribute extra costs, one way or the other. Our tractor-tooting farmers instinctively know this.
What they might not fully realise is they are up against the tide of history.
Global warming is serious, the political response will get more serious. Eventually, farmers will pay a price for at least some of the carbon they emit, like other industries. Or they risk being locked out of export markets (as Jacinda Ardern keeps warning).
As unhappy as farmers will be about being brought into the Emissions Trading Scheme, or subject to other costs that reduce emission rates, this is only the precursor to the main event.
Energy will get more expensive as global oil reserves decline.
It's not just about what's used on the farm, but the trucks, milk tankers, ships, and jets transporting food products to national and international markets.
The decline in the availability of cheap fossil fuel will revolutionise farming in reverse.
Smaller farms that use more human and animal labour, and are more self-sustaining, will find their niche again. Massive industrial farming for export will enter a period of crisis.
The age of giant tractors will eventually chug to an end. Maybe not in my lifetime or in the lifetimes of many of those I saw driving their tractors through Whangārei.
There were, though, a few smiling kids in the tractor cabs who will probably see a way of life pass.
They'll have a story to tell of the day they drove through town with their dad or mum on a giant diesel tractor.
• Northern Advocate columnist Vaughan Gunson writes about life and politics