P and K

Dave6170

Member
Oh... that stuff, don't quote me because I can't remember but I seem to remember that stuff is pretty insoluble being rock phosphate. I can only remember using it on an organic place? Might be wrong mind.
Thats the stuff that we have used on reseeds for years. But obviously not enough.
Whats the difference between scotphos and tsp?
 

Brisel

Member
Location
Dorset
Scotphos is based on soft rock phosphate. Normally, rock phosphate makes me shout "b*llocks!" as it is virtually inert on anything other than acidic soils. I haven't seen this Scotphos before unsurprisingly as I'm near the South Coast of England but I do think it's suspicious. I've been offered GAFSA rock phosphate before and was advised to stay well clear of it on alkaline soils as I'd never see it back again, locked away for eternity.

The marketing blurb does say it can be used for low P index soils and it is sold as a powder which will improve its availability vs a granule though you'll need a lime spreader to apply it. What is your soil pH? If it's over 7 I would avoid this Scotphos stuff. If you've got very low P levels in your soil a much more soluble version like DAP or MAP would bring levels up quickly. TSP is also soluble enough for what you want.

http://www.originfertilisers.co.uk/products/gafsa-p-and-pk/
 

hally

Member
Location
cumbria
If I want to take and send soil samples myself direct, where can I send them if I want to avoid the local agronomy company?
 

Dave6170

Member
Scotphos is based on soft rock phosphate. Normally, rock phosphate makes me shout "b*llocks!" as it is virtually inert on anything other than acidic soils. I haven't seen this Scotphos before unsurprisingly as I'm near the South Coast of England but I do think it's suspicious. I've been offered GAFSA rock phosphate before and was advised to stay well clear of it on alkaline soils as I'd never see it back again, locked away for eternity.

The marketing blurb does say it can be used for low P index soils and it is sold as a powder which will improve its availability vs a granule though you'll need a lime spreader to apply it. What is your soil pH? If it's over 7 I would avoid this Scotphos stuff. If you've got very low P levels in your soil a much more soluble version like DAP or MAP would bring levels up quickly. TSP is also soluble enough for what you want.

http://www.originfertilisers.co.uk/products/gafsa-p-and-pk/
What is Dap and map? Whats the difference?
Local guys dont like tsp they recommend scotphos type stuff. Say it doesnt last?
 

Brisel

Member
Location
Dorset
Diammonium phosphate 18.40.0 and monoammonium phosphate 12.52.0 Very soluble and also supply nitrogen.

Who are the “local guys?” Since I’ve got little background information here I recommend you talk to a FACTS qualified agronomist with no agenda to sell you their products. I'm not writing off materials like Scotphos if they are cheaper than straights like TSP. With the money you save on a cheaper product, you could apply a higher dose that would increase the amount available for what you need.
 

Brisel

Member
Location
Dorset
Here's a screenshot from the SRUC website:
upload_2019-1-20_14-27-28.png


No mention that I can find of methodology by searching on their website.
 

scholland

Member
Location
ze3
I think sruc use "modified morgans". Morgans was developed by macaulay for Scottish soils but I think it takes a while to do so isn't commercially used.
Nrm use olsen I think.
 

Bogweevil

Member
P is P, so the material spreadable with the farm's equipment that offers the cheapest P as extractable with citric acid + water soluble would be the one to choose, no? Do the maths, yes?

Still miss basic slag, sigh.
 

Brisel

Member
Location
Dorset
Some will be. On calcareous soil or where continuous brassica veg is grown and pH is above 7.5 you'll be unlikely to see any of that fertiliser again.
 

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