Applying no bagged P or K to crops

HarryB97

Member
Mixed Farmer
I have increasingly been reading that more no till farmers are applying no bagged P or K and find that their indices are not decreasing. Are any members on here finding the same? We have recently moved to no till and the back bone of our rotation is 3-4 year grazed and silaged leys, all straw removed for our cattle and around 30-40% spring cropping using over winter covercrops which are grazed by our sheep. My thinking is the more alive and healthy your soil is the more locked away nutrients you can access?
 

ajd132

Member
Arable Farmer
Location
Suffolk
You’ll still be mining your soil, whether your nutrients are locked away or not.
Like any farming system, you have to replace nutrients you remove from the soil.
The thinking and research is beginning to change on all this.
 

Chae1

Member
Location
Aberdeenshire
I have increasingly been reading that more no till farmers are applying no bagged P or K and find that their indices are not decreasing. Are any members on here finding the same? We have recently moved to no till and the back bone of our rotation is 3-4 year grazed and silaged leys, all straw removed for our cattle and around 30-40% spring cropping using over winter covercrops which are grazed by our sheep. My thinking is the more alive and healthy your soil is the more locked away nutrients you can access?
Was at a farm visit and they had loads of pigs and cows. Farm at limit with how much there applying.

He was still applying 25 units of P&K out of bag. Speaking to farmer and agronomist and they didn't feel cutting it out completely was a option.
 

Jerry

Member
Mixed Farmer
Location
Devon
I’ve pretty much stopped bagged P&K but it’s replaced with rotational grazing, Biosolids and compost in all arable ground going forward.

It’s a long term approach though and I will top up a little by soil tests but most field indexes have been stable for 5 years now.

Biggest different has been livestock back on arable ground each winter. Fields in their second rotation of grazing are showing a marked improvement.
 

Hampton

Member
Location
Shropshire
The thinking and research is beginning to change on all this.
Doesn’t mean they are right.
Apparently they believe 0 + 0 = 1
I’m not saying you need inorganic fert, but you definitely need to add something back be it muck or cover.
 

farmerm

Member
Location
Shropshire
Doesn’t mean they are right.
Apparently they believe 0 + 0 = 1
I’m not saying you need inorganic fert, but you definitely need to add something back be it muck or cover.
Cover crop may put back some N but P and K can not be pulled from fresh air. Sell 4T of wheat and f you don't put anything back you sell about 20kg of potassium mined from your soil, even if your soil start with significant reserves, all mining operations eventually run out of resources. You may be able to make them more available but you will never "regenerate" P and K in soils.
 

Charles Quick

Member
BASE UK Member
Location
Somerset
Cover crop may put back some N but P and K can not be pulled from fresh air. Sell 4T of wheat and f you don't put anything back you sell about 20kg of potassium mined from your soil, even if your soil start with significant reserves, all mining operations eventually run out of resources. You may be able to make them more available but you will never "regenerate" P and K in soils.
No, but approximately 90-98% of P and K exists in the soil as insoluble minerals (i.e. rock). And if I remember correctly a large proportion of bagged P & K are converted to insoluble forms before it is used by the plant. In other words, mineralisation of these resources can provide hundreds of years of nutrition until the soil is truly 'depleted'. The rhizosphere of various plants and mycorrhizal fungi are able to solubilise these rock sources, and that is where I see the potential of regenerative agriculture.
 

martian

DD Moderator
BASE UK Member
Location
N Herts
No, but approximately 90-98% of P and K exists in the soil as insoluble minerals (i.e. rock). And if I remember correctly a large proportion of bagged P & K are converted to insoluble forms before it is used by the plant. In other words, mineralisation of these resources can provide hundreds of years of nutrition until the soil is truly 'depleted'. The rhizosphere of various plants and mycorrhizal fungi are able to solubilise these rock sources, and that is where I see the potential of regenerative agriculture.
Not only rocks...clay has a very high CEC and will lock up no end of P & K and other nutrients. Fungi and bacteria are your friends here, that's why a healthy soil (which will be humming with microbial activity), doesn't need more added. We haven't put any bagged P &K on for ten years or so, indices are stable or rising, soil life is improving all the while. If you do add fertiliser, the mycorrhizae will shut up shop, lose/lose situation. Most agronomists are still thinking in the old 'extractive' mindset. Ignore their advice!
 

ajd132

Member
Arable Farmer
Location
Suffolk
No, but approximately 90-98% of P and K exists in the soil as insoluble minerals (i.e. rock). And if I remember correctly a large proportion of bagged P & K are converted to insoluble forms before it is used by the plant. In other words, mineralisation of these resources can provide hundreds of years of nutrition until the soil is truly 'depleted'. The rhizosphere of various plants and mycorrhizal fungi are able to solubilise these rock sources, and that is where I see the potential of regenerative agriculture.
Spot on. The phosphate mines will run out long before the true potential of what is in the soil.
 

Hampton

Member
Location
Shropshire
That’s all true, but that is not because of no till (which is what the OP is getting at, it’s in many cases because people aren’t growing wheat/rape rotations and are adding legumes, cover crops, compost etc into the farming system.
 

ajd132

Member
Arable Farmer
Location
Suffolk
That’s all true, but that is not because of no till (which is what the OP is getting at, it’s in many cases because people aren’t growing wheat/rape rotations and are adding legumes, cover crops, compost etc into the farming system.
No till helps in an arable situation because it doesn’t ruin the fungal and bacterial networks but it is only a small part of the whole thing.
 

Kildare

Member
Location
Kildare, Ireland
Not only rocks...clay has a very high CEC and will lock up no end of P & K and other nutrients. Fungi and bacteria are your friends here, that's why a healthy soil (which will be humming with microbial activity), doesn't need more added. We haven't put any bagged P &K on for ten years or so, indices are stable or rising, soil life is improving all the while. If you do add fertiliser, the mycorrhizae will shut up shop, lose/lose situation. Most agronomists are still thinking in the old 'extractive' mindset. Ignore their advice!
I would like to think you are right but I bought a grass farm 30 years ago that was used for grazing and not fertlized with artificial fertiliser. It had not been ploughed or tilled for generations.
So the soil bacteria were undisturbed and should have been releasing all this locked up p and k.

But when we soil tested it it was very poor in nutrition. First crop of wheat went purple for lack of p.
There was a old farmer called Hollis whose farm was organic for generations in the UK. His son Ben has it open to the public and its a sort of community farm.
I called to see it and the grass was black green. The secret was a big pile of hen poo.
I don't think you can take off 4 ton of grain and straw every year without fertiliser of some sort.
Continous grazing offers the best chance of farming without fertiliser but the soil index will be extremely low. Imo.
 

7610 super q

Member
Arable Farmer
No, but approximately 90-98% of P and K exists in the soil as insoluble minerals (i.e. rock). And if I remember correctly a large proportion of bagged P & K are converted to insoluble forms before it is used by the plant. In other words, mineralisation of these resources can provide hundreds of years of nutrition until the soil is truly 'depleted'. The rhizosphere of various plants and mycorrhizal fungi are able to solubilise these rock sources, and that is where I see the potential of regenerative agriculture.
So.......if I plough a bit deeper and bring up more rocks, I'm replenishing P & K ? :cool:

Just kidding.:rolleyes:
 

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