Flindt on Friday: Say what you will, low inputs mean low outputs

Name calling: it’s not big, and it’s not clever. Luckily, after a lifetime being fat, ugly and ginger, I’m immune to it.

And I’ll need all that immunity because, once again, I’ve been investigating the mystical world of regenerative farming, and its disciples are very hostile to questioning.

I’m baffled by the “no added P and K” claim, which has become a key boast of almost every regen farmer.

About the author

Charlie Flindt
Charlie Flindt is a tenant of the National Trust, farming 380ha in Hampshire with his wife, Hazel. He’s a weekly columnist writing for Farmers Weekly and never fails to raise a few eyebrows and tickle a few funny bones with his hilarious musings about the farming world.
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My first stop, to check some basics, was a well-thumbed 1983 uni copy of Fream’s Agriculture, still lurking on the farmhouse bookshelves.

And in the chapter on Fertilisers and Manures, this authoritative tome is quite clear:

“All soils contain a stock of essential elements that are plant nutrients, and the size of the reserves determines the fertility of the soil. Where the annual growth is ‘harvested’, the nutrients that have been taken up are lost to the ecosystem. Unless natural processes make good the annual loss, the fertility of the site will decline.”

See also: Flindt on Friday: The fine art of baffling your neighbours

Old-school farmers have a name for “not making good the loss”: quarry farming – and it’s not meant as a compliment.

“Ah,” cry the Regens, “that’s old news. We’ve got the ‘natural processes’ – we’ve got special bacteria and cover crops that release previously locked-in nutrient reserves.”

(We’ll save those special farmers who claim “no added P and K”, but pile on mountains of digestate or pig slurry, often from other farms, for another column, shall we?)

That may well be true, but there’s still something not right about carting off nutrients and not replacing them in the old-fashioned way.

Books on a bookshelf, including Fream's Agriculture

© Charlie Flindt

So I went hunting for more info, to see if I was being the dinosaur, and if such modern-day alchemy was possible.

It certainly goes against all my agricultural education. I simply don’t believe that ostentatiously claiming to be “working with nature” will produce everything you’ll ever need.

And I stumbled upon an article by academic Andrew McGuire of Washington State University: “How does regenerative agriculture reduce nutrient inputs?”

Funnily enough, far from condemning the venerable Freams to the agri-dustbin, it backs up everything that the aged book says, and we dinosaurs have claimed for ever: low inputs are only possible with low outputs.

The professor says:

“Regenerative agriculture in this form may not be a good strategy for reducing inputs in staple food-crop production, at least not until our population stops growing. Regenerative agriculture does reduce inputs, but the primary mechanism by which it does this is the reduction of nutrient exports from the field. All the other factors; soil biology, mycorrhizal fungi, diversity effects (other than including legumes), and mineral weathering, are minor factors.”

But my favourite quote is this:

“One recent paper (Menezes-Blackburn et al, 2018) estimates that legacy [existing] P could supply P for the next 100 years, [but] not necessarily at a rate sufficient for high-yield annual cropping.”

The “limited harvests left” theory might be true, after all. It seems there could be only 100 left – poor ones, too – under regenerative agriculture.

As for reserves of the good old bagged stuff?

In 2021, the United States Geological Survey estimated that economically extractable phosphate rock reserves worldwide were 71bn tons, while world mining production in 2020 was 223m tons.

Which works out as? You do the maths. I’m too busy trying not to sink to the level of undignified name calling.