Fertiliser NPK ratios

I do not understand why NPK ratios are not reduced to the smallest whole number. Surely NPK 7-7-7 could be 1-1-1? Or have I misremembered O-level maths which admittedly was a long time ago?

 

I've always thought it was because it sounds like you are getting more for your money.
Maybe its to do with the content of fertiliser per weight as its chemicals are usually on some kind of carrier substance.

 

You are probably right @pete, that it sounds like more for your money.

 

Thank you @JWK, I think I understand that.

 

Agreed.
Remember that it applies to the weight/area, such as 75kg/ha or 4ozs. per sq yard, hence calculations done to amend the results of soil testing. Too much can be adverse in mineral locking as well as being expensive. Regenerative methods are more fashionable, utilising natural processes to achieve the end result, rather than bombing crops with chemicals. This should result in more nutrient-rich foodstuffs; correcting some of the destruction caused over the recent (100 yrs )past.
I declare an interest !
My maternal great- grandfather was Balliff at Wallscourt Farm , Stoke Gifford when redeveloped by H Proctor to create The Model Farm to demonstrate efficicy of the (then) new chemical fertilisers invented by H &T Proctor Ltd in 1853.
The History Of Proctors | Proctors NPK
0044a…Wallscourt Farm Plan & Photos of the Buildings

 

Yet the whole discourse about less nutrient rich crops is largely a fallacy due to inconsistent ways that was measured in the past and frankly just a buzz word used to bolster arguments about a specific type of farming.

The Myth of Growing High Nutrient Density Food

James Wong keeps telling people it is a useless generalisation on Twitter since at least 2018

 

So the science, for you and James Wong, is settled.
Others may differ.
https://www.frontiersin.org/articles/10.3389/fsufs.2021.699147/full

 

If James Wong says it, it must be true.......?

 

Wot could go Wong!

 

For every 100 grams of 7-7-7 there will be 7 grams each of the NPK values, where as 1-1-1 would only have 1 gram of each per 100 grams.

I had a very disgruntled, rude customer saying that the Blood Fish & Bone he purchased should of had an NPK value of at least 33-33-33 and that current retail of 5-5-6 was a rip off, he was like a dog with a bone. It was a nightmare trying to explain to him that a fertiliser that potent would be a nightmare to apply the correct ratio for a professional, let alone a first time gardener. It's a bit like complaining in every pub when you go out for a drink, your never going to get a beer, wine or spirit that has 100% ABV

 

There's just no pleasing [or telling] some folk @gks. Working with the public eh?