Soil analysis accuracy.

Stw88

Member
Location
Northumberland
Had some fields tested in August 2019 and applied lime @ 2t acre. just had the same fields retested and one that was ph5 has now lifted to 5.5 Which is just what I was expecting it to be. Now the field right next to it similar soil type but a hay field was 5.4 and has retested at 6.4. Is it possible that it could of increased that much in 20 months? Or was the original test wrong or the recent on? There is also a big variation in the P index in the first field and the K index in the second 🤔 I am aware that time of year and how dry or wet the soil is can alter results but both were done the same time and conditions.
 

Stw88

Member
Location
Northumberland
If it was good quality lime I would expect 2t per acre to lift it one full pH point.

However, that said, I don’t agree with the drying and grinding of soil for pH sampling in a lab.
Getting chalk lime from singleton birch, seams good fine powdery stuff. does the ph lift more easily the higher it is to start with? Just wondering why one has lifted by .5 and the other a whole point.
 

Thick Farmer

Member
Location
West Wales
Had some fields tested in August 2019 and applied lime @ 2t acre. just had the same fields retested and one that was ph5 has now lifted to 5.5 Which is just what I was expecting it to be. Now the field right next to it similar soil type but a hay field was 5.4 and has retested at 6.4. Is it possible that it could of increased that much in 20 months? Or was the original test wrong or the recent on? There is also a big variation in the P index in the first field and the K index in the second 🤔 I am aware that time of year and how dry or wet the soil is can alter results but both were done the same time and conditions.

It’s a logarithm. It takes a lot of lime to lift pH a small amount initially. However, once pH is higher it takes less lime to raise it further.
 
Had some fields tested in August 2019 and applied lime @ 2t acre. just had the same fields retested and one that was ph5 has now lifted to 5.5 Which is just what I was expecting it to be. Now the field right next to it similar soil type but a hay field was 5.4 and has retested at 6.4. Is it possible that it could of increased that much in 20 months? Or was the original test wrong or the recent on? There is also a big variation in the P index in the first field and the K index in the second 🤔 I am aware that time of year and how dry or wet the soil is can alter results but both were done the same time and conditions.


I was once told by NZ AgResearch's Head of Soil Science that almost all the variation in soil test results occur due to SAMPLING INADEQUACIES i.e. insufficient samples, lack of blending the samples before a sub sample is submitted, samples taken either too shallow or too deep, too much organic matter (plant material), too soon after liming and or any fertilisers applied, in urine patches, etc. etc. His concluding comment was "you can never over sample if you want a true indication of the current soil chemical status".
 

Agrivator

Member
If it was good quality lime I would expect 2t per acre to lift it one full pH point.

However, that said, I don’t agree with the drying and grinding of soil for pH sampling in a lab.

ph is a measure of Hydrogen ion activity, and each unit change in ph represents a ten-fold change in hydrogen ions. In advisory work, I have normally worked on the principle that 1t/acre of ground limestone will lift ph by 0.25 in the top 9'' of soil. In other words, a mineral soil at 5.5ph would need 2t/acre to lift it to 6.0ph to normal plough depth.

But lime spread on the surface and not mixed in will lift the surface ph by a greater amount, and it takes more time to affect ph at lower levels.

As soils become more acidic, there is an increase in aluminium ions, and it is aluminium toxicity which retards growth in most plants. It affects some plants more than others. Oats and Yorkshire Fog are more tolerant than Barley or Perennial Ryegrass.

And a bit of lime in a bulked-up soil sample won't have a massive effect on the resulting ph. Calcium carbonate has a ph of less than 10. Otherwise nothing would grow on chalk soils,
 
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Your first paragraph is certainly not my experience. I consistently find one tonne of good quality ground lime to lift pH by at least half a pH point.

I’m sure my customers would have noticed by now if that wasn’t the case.

I agree with your last paragraph except that a bit of lime in a bulk sample of soil sent to a lab will affect the result. It won’t if it’s left as a fragment but if it is ground to a fine powder then it most certainly will.

I’ve demonstrated a similar effect many times with my customers if we get talking on the subject of lab testing. We take a nice yellow/orange test tube sample and scrape a small amount of cement from the nearest wall or even a tiny bit of lime if I have some with me. Within seconds, the result has changed to a higher ph.

As with many things theory and lab results can be one thing, practical results can be another.
 
Location
Ceredigion
The main driver is the qualtily of lime but have used lime over 40 years I see no problem here with 2 ton lifting 1.0 , but also depends how deep you sample and how deep you plough ,
 
Location
Ceredigion
Had some fields tested in August 2019 and applied lime @ 2t acre. just had the same fields retested and one that was ph5 has now lifted to 5.5 Which is just what I was expecting it to be. Now the field right next to it similar soil type but a hay field was 5.4 and has retested at 6.4. Is it possible that it could of increased that much in 20 months? Or was the original test wrong or the recent on? There is also a big variation in the P index in the first field and the K index in the second [emoji848] I am aware that time of year and how dry or wet the soil is can alter results but both were done the same time and conditions.
The hay field would normally show a lower k level depending on whats been put on
 

neilo

Member
Mixed Farmer
Location
Montgomeryshire
I was always led to believe soil analysis should always be done at the same time of year, as the soil biology will change results between winter & summer. Retesting the same field after 6 months would give a different result, even without anything applied.

Is that advice not correct @Cab-over Pete? :scratchhead:
 

yellowbelly

Member
Livestock Farmer
Location
N.Lincs
. Is it possible that it could of increased that much in 20 months?
Getting chalk lime from Singleton Birch, seams good fine powdery stuff.
There's your answer then - top quality ground chalk from a good Lincolnshire outfit ;)

On a more serious note, as said above, the results of soil sampling are only as good as the bloke who took the sample.
 
I was always led to believe soil analysis should always be done at the same time of year, as the soil biology will change results between winter & summer. Retesting the same field after 6 months would give a different result, even without anything applied.

Is that advice not correct @Cab-over Pete? :scratchhead:

There could well be something in that Neil. I always think that the soil should be sampled in its most natural state, moist and friable with a growing crop on it.
 
Things have changed in the way lime and ph are calculated. I’m no expert I’m only learning but I keep hearing bits.
Back in the 80s father was big into the ADAS thing the man was never away from here. I’m sure if my memory serves me right he was putting on lime at rates of 4 /4.5 tonnes acre as a prescription. I still ask contractor to put it on at 3.5t acre and he won’t do it won’t go over 3. New way is to do what you have done and put on 2 t acre and re test later. Also there’s talk of neutralising values and sieve size of lime. Bigger stuff takes time to work any lime takes a year to get going in my experience
 
I don’t like to apply more than 2.5t per acre in one hit. In extreme circumstances I might go to 3t per acre.

on sieve size, we have to get away from this idea that bigger lumps of lime last longer. In the case of chalk, being soft, those bigger lumps can break down in the soil, but I honestly don’t think lumps of limestone do.

If you look at really old cottages built from it, they have formed a crusty layer, which protects the stone. If that didn’t happen, they would melt away. I think the same thing must happen to some extent in the soil. There must be some kind of time frame for it to happen and I wouldn’t have a clue what that is, but if the soil doesn’t break the lump down soon enough, I think a crusty layer will form around it rendering it useless.

I can’t remember ever seeing a cottage built from chalk.

That’s the reason I won’t supply cheaper screened lime. I don’t think the lumps the size of your thumb nail do any good.

Anyway, sampling. I think if an advisor tried to recommend regular applications of 4t/ac these days there would be some raised eyebrows!!
 
Location
Ceredigion
If it takes a year to work and ph is 5 or less how can putting 3 ton on be harmful. I will continue to apply as I was taught from the old guys . Call me a stubborn mule if you want
And if I want quick results for direct drilling then I will use .....
 
I don’t like to apply more than 2.5t per acre in one hit. In extreme circumstances I might go to 3t per acre.

on sieve size, we have to get away from this idea that bigger lumps of lime last longer. In the case of chalk, being soft, those bigger lumps can break down in the soil, but I honestly don’t think lumps of limestone do.

If you look at really old cottages built from it, they have formed a crusty layer, which protects the stone. If that didn’t happen, they would melt away. I think the same thing must happen to some extent in the soil. There must be some kind of time frame for it to happen and I wouldn’t have a clue what that is, but if the soil doesn’t break the lump down soon enough, I think a crusty layer will form around it rendering it useless.

I can’t remember ever seeing a cottage built from chalk.

That’s the reason I won’t supply cheaper screened lime. I don’t think the lumps the size of your thumb nail do any good.

Anyway, sampling. I think if an advisor tried to recommend regular applications of 4t/ac these days there would be some raised eyebrows!!
I honestly don’t know. You will know a lot more about it than I do. I’m just going off what happens here. Usually takes a year to work otherwise to see any benefit and probably might be more economical on lime not to put much over 2t an acre on in one go. I personally have never put less than 2.5 tonnes per acre on
 

Johngee

Member
Livestock Farmer
Location
Llandysul
As soils become more acidic, there is an increase in aluminium ions, and it is aluminium toxicity which retards growth in most plants. It affects some plants more than others. Oats and Yorkshire Fog are more tolerant than Barley or Perennial Ryegrass.
I remember hearing a talk by a soil scientist from NZ (@Global ovine would know who I’m talking about) a few years ago who said something very similar. If the pH gets very low then ordinary lime will struggle to lift the values as the aluminium will bind with it preventing it from working. He said that at very low pH’s you need something like burnt lime to over come this. But I don’t think you can get it now.
 
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Update on the Sustainable Farming Incentive pilot

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Update on the Sustainable Farming Incentive pilot

Written by Lisa Applin

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In July, we opened the applications window for farmers to join our Sustainable Farming Incentive pilot.

The Sustainable Farming Incentive is 1 of the 3 new environmental land management schemes. It sits alongside the future Local Nature Recovery and Landscape Recovery schemes.

Through the Sustainable Farming Incentive, farmers will be paid for environmentally sustainable actions – ones that are simple to do and do not require previous agri-environment scheme experience.

We are piloting the scheme to...
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