Calcium vs. Mag Lime Based on Soil Test

Gibbybox

Member
Hi folks,

I have agreed in principle to the renewal of a 5 year lease on a 100ac block of land, mainly for sheep grazing with 20 suckler cows/calves and one cut of silage in the same field each year.

Over the past 5 years I have managed to increase stocking density massively using rotational grazing but nonetheless feel the place has a lot more potential. I had soil testing done last year to get a feel for what might be needed to make the ground more productive in the event a renewal was agreed.

Based on the attached, I understand the pH to be very low at 5.3 in a typical grazing field and 5.5 in the regular silage field, as well as significant K, sulphur and sodium deficiencies. My initial plan is to get 2t of lime/ac on the whole place as soon as possible, before improving the potash deficiency later in the spring/summer with application of 25-0-14 or similar.

My main dilemma at the moment is what type of lime to put on. I applied 1t/ac of good quality ground calcium lime to the whole place at the start of the previous 5 year period but it seems to have hardly scratched the surface, hence going for 2t this time.

Mag lime is circa £30/ac spread in my area and it's £38/ac spread for calcium lime, adding up to £1600 difference overall! I'm struggling to justify the extra cost and have been advised that the mag lime will do just as good a job, while being less susceptible to blowing onto the neighbours (as it seemed to do last time in at least some fields). However, I'm slightly concerned with the 'high' mag test of 106/51 and the impact applying more mag in the form will have on this. To confuse things further, I have another field test at a different place with 82/51 recorded (categorised as 'normal') and the recommendation is to apply mag there to get it up a bit which I am struggling to follow.

Do any of the TFF collective have an opinion on calcium vs. mag lime? Thinking mainly about risk to cattle due to staggers risk and related benefits of addressing the calcium/mag balance with an application of calcium lime. The ability to get mag lime of that quantity delivered and spread in the dry, and with very little wind is also a consideration as the stars might not all align.

Many thanks for your help!
 

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Location
Ceredigion
Dont put Mag on, but price means nothing. I can get lime tipped for £25 and limed tipped for £30 , the £30 is cheaper as the tnv value is a lot higher , don't get blinded by the NV Value as its meaningless if the limes to course
 

Macsky

Member
Livestock Farmer
Location
Highland
Are you likely to get another 5 years? There may be a slight risk of mineral lock up from the 2t, and if you’re puting it across the whole place then you might see some problems, may be a better idea to go 3t/ac but not cover everything, as in the rotation they would be exposed to ground that hadn’t been limed and in theory get access to any minerals that may be locked up by the lime.

I wouldn’t touch course mag lime with a barge pole, the calcium is the stuff to go for.
 

Gibbybox

Member
Thanks for the feedback folks. I’m half tempted to put a reduced rate of calcium lime on (1.5t/ac) which would bring the options closer in cost and perhaps be a better compromise.

The advice I’ve been given is the fundamental problem I have is very low pH and it would therefore be better to get 2t of mag on rather than 1.5 of calcium on to make the biggest difference to the pH. However, I don’t want to suffer elsewhere as a result.

It’s really not my area of expertise but I’ve a contractor (and good friend) telling me mag lime on one hand and the old man adamant on calcium lime on the other, so no obvious answer.
 

Gibbybox

Member
Are you likely to get another 5 years? There may be a slight risk of mineral lock up from the 2t, and if you’re puting it across the whole place then you might see some problems, may be a better idea to go 3t/ac but not cover everything, as in the rotation they would be exposed to ground that hadn’t been limed and in theory get access to any minerals that may be locked up by the lime.

I wouldn’t touch course mag lime with a barge pole, the calcium is the stuff to go for.
Yes further 5 years agreed in principle and every confidence it will go ahead. My understanding is not to apply more than 2t at a time so I don’t think I’ll be going above that, just deciding on the mag vs. Calcium is the issue.

Dad’s opinion is like yours, nothing except calcium is worth having. Contractor (and friend, so is keen to advise ) sees that as old fashioned thinking and spreads mostly mag lime for livestock boys on rented ground.
 

Gibbybox

Member
£1600 difference sounds a lot, until you realise its only a paltry £3.20 a year per acre for a better product.
Also you need to ask what the pH5.3 has cost you in lost grass and quality over the previous 5 years, which will be significantly more than the total cost of the lime.
Definitely a good way to look at it. I’m definitely aware the 5.3 is not a great place to be and am keen to do something about it as soon as possible now I have a bit of security.

With a big rent payment due in June as well as other costs due before any income later in year, I think I’ll have to go for either 1.5t calcium or 2t mag as a maximum. With such a low pH at the moment I can see the contractors argument for 2t mag but will sleep on it I think. Many thanks for your input folks 👍🏻
 
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Just do the liming process in 2 or 3 hits to spread the pain?

With numbers like those I wouldn't mess about, 2 tonne is the rate. Without spending the money on lime you are going to have invisible losses in grass growth, stock carrying capacity and also less effective fertiliser use. All this lot will soon make £1600 look cheap.
 
Location
Ceredigion
Definitely a good way to look at it. I’m definitely aware the 5.3 is not a great place to be and am keen to do something about it as soon as possible now I have a bit of security.

With a big rent payment due in June as well as other costs due before any income later in year, I think I’ll have to go for either 1.5t calcium or 2t mag as a maximum. With such a low pH at the moment I can see the contractors argument for 2t mag but will sleep on it I think. Many thanks for your input folks
I would sooner do 20 acres right than mess about with 40 and to much mag can
do harm . Your putting petrol in a diesel car to be honest. But your fields
 

Sid

Member
Livestock Farmer
Location
South Molton
Just do the liming process in 2 or 3 hits to spread the pain?

With numbers like those I wouldn't mess about, 2 tonne is the rate. Without spending the money on lime you are going to have invisible losses in grass growth, stock carrying capacity and also less effective fertiliser use. All this lot will soon make £1600 look cheap.
When I took on a block, did 2t/ acre across the whole lot.
If cash flow was an issue I would split 50/50 first 2 years.

Question is, do you do half at full rate or all at half rate?
 
Half at full rate.

Many times over the years, folks have put half rate over a whole block of land and said it didn’t really make much difference.

Well, it won’t, will it? You wouldn’t put half a tank of fuel in your tractor and expect it to chop grass all day and half the night, would you?

Do half the ground at full rate and see a difference.
 

Rejuvenating swards: Which option is best?

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Written by Brian McDonnell

Maintaining grass quality during mid-season grazing is important. Farmers can maintain quality by entering ideal grazing covers of 1,300 – 1,500kg DM/ha, and grazing down to a residual of 4cm every rotation.

If you are now in a situation where cows are not cleaning out paddocks as well as they should be, leading to the development of steamy grass within the sward, here are some options.

Common options for rejuvenating swards include:

  1. Take a silage cut, probably into bales, remove the material and start again with the aftermath...
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