Sulphate of potash

Thedual1

Member
Not a cheap product, but because it is potassium sulphate there is no nasty chlorine like muirate of potash. Chlorine is not too bad in light soils as it can dissipate through the soil profile. Clay and heavy soils are a different kettle of fish.

I get round the cost by doing a 50/50 blend of MOP/SOP which gives 50-55% potash 50% sulphate and 50% muirate and 22.5%So3 (sulphur worth about £0.80/unit)

Another option is using muirate of potash and polysulphate which would be the cheapest option this gives 42% potash and 18% So3 this also gives 6.2% calcium and 2.2% magnesium
 

Thedual1

Member
Sulphate of potash is an expensive product but you miss the point in the value of sulphur. SOP has 45%So3 which is worth £0.80/unit.

With no heavy industry in the UK sulphur is becoming very deficient.
 

Thedual1

Member
I don't know, it's a good question. There's a high K fibrophos, maybe that's how they do it.
Fibrophos is just burnt chicken muck, that add SOP to it if you need potash. It is good stuff but not good to spread. Work out the cost to put on the desired level of potash.

Think Fibrophos with potash was sub £200/t but what rate do you need to supply 40 - 50 units potash

MOP/SOP blend should be £350-£370

And my special made with Polysulphate about £245/t
 

phil

Member
Location
Wexford
Not really. Or put it this way I don't think K chloride is any worse than K Sulphate seems to be a . I think the salt thing is misleading. Would be interesting to see a salt index of all ferts to compare!
I have a salt index of fert somewhere I'll try find its

I like the idea of polysulphate and mop

Shame polysulphate is a little expensive for what it is
 
Location
Cambridge
Sulphate of potash is an expensive product but you miss the point in the value of sulphur. SOP has 45%So3 which is worth £0.80/unit.

With no heavy industry in the UK sulphur is becoming very deficient.
It's still more expensive than MOP when you take the sulphur into account, but not by as much as it looks on first inspection
 
Not a cheap product, but because it is potassium sulphate there is no nasty chlorine like muirate of potash. Chlorine is not too bad in light soils as it can dissipate through the soil profile. Clay and heavy soils are a different kettle of fish.

I get round the cost by doing a 50/50 blend of MOP/SOP which gives 50-55% potash 50% sulphate and 50% muirate and 22.5%So3 (sulphur worth about £0.80/unit)

Another option is using muirate of potash and polysulphate which would be the cheapest option this gives 42% potash and 18% So3 this also gives 6.2% calcium and 2.2% magnesium

There isn't chlorine in muriate of potash for goodness sake!
 
Location
Cambridge
There isn't chlorine in muriate of potash for goodness sake!
Neither is chlorine used as a disinfectant, it's sodium hypochlorite. When you dissolve this in water you get the chloride ions, which are the harmful things. Is that the same net result as putting MOP into the soil? I don't know, but think it probably is. Not sure if it's enough to cause problems though.

Edit: MOP does dissociate into chloride ions in a water solution, so it should have the same sort of biocidal effect as bleaches etc.

So the fact there isn't chlorine in MOP is pretty irrelevant from what I can see.
 

Richard III

Member
Location
CW5 Cheshire
Neither is chlorine used as a disinfectant, it's sodium hypochlorite. When you dissolve this in water you get the chloride ions, which are the harmful things. Is that the same net result as putting MOP into the soil? I don't know, but think it probably is. Not sure if it's enough to cause problems though.

Edit: MOP does dissociate into chloride ions in a water solution, so it should have the same sort of biocidal effect as bleaches etc.

So the fact there isn't chlorine in MOP is pretty irrelevant from what I can see.
MOP is just a salt, no more toxic than table salt. Infact you can buy low sodium salt for the dining table, which is a mix of salt and MOP.

Sodium Hypochlorite is a totally different beast, and I would not want to put it on my chips. :eek:

Sodium hypochlorite is the salt formed by a negatively charged hypochlorite ion (OCl-) and a positively charged sodium ion (Na+). Pure hypochlorite is highly reactive and unstable; therefore, it is usually supplied as a dilute aqueous solution. In solution, hypochlorite eventually decomposes to yield a variety of byproducts including oxygen, chlorine gas, and salt. One of these byproducts, hypochlorous acid, is a powerful oxidizing agent (meaning it can accept electrons from other materials) that lends hypochlorite excellent bleaching and disinfecting abilities. The term "available chlorine" is often used to describe the concentration of hypochlorous acid in solution (which provides a measure of the solution's oxidative ability).
 
Location
Cambridge
MOP is just a salt, no more toxic than table salt. Infact you can buy low sodium salt for the dining table, which is a mix of salt and MOP.

Sodium Hypochlorite is a totally different beast, and I would not want to put it on my chips. :eek:

Sodium hypochlorite is the salt formed by a negatively charged hypochlorite ion (OCl-) and a positively charged sodium ion (Na+). Pure hypochlorite is highly reactive and unstable; therefore, it is usually supplied as a dilute aqueous solution. In solution, hypochlorite eventually decomposes to yield a variety of byproducts including oxygen, chlorine gas, and salt. One of these byproducts, hypochlorous acid, is a powerful oxidizing agent (meaning it can accept electrons from other materials) that lends hypochlorite excellent bleaching and disinfecting abilities. The term "available chlorine" is often used to describe the concentration of hypochlorous acid in solution (which provides a measure of the solution's oxidative ability).
OK, fair enough. But then consider this:

http://www.sciencedirect.com/science/article/pii/S0038071714000315

• Increasing the Cl concentration inhibited the soil nitrification.

• The association of AC and KCl reduced the microbial biomass.

• Chloride ions inhibit nitrification and are therefore a potential soil biocide.
 

Richard III

Member
Location
CW5 Cheshire
OK, fair enough. But then consider this:

http://www.sciencedirect.com/science/article/pii/S0038071714000315

• Increasing the Cl concentration inhibited the soil nitrification.

• The association of AC and KCl reduced the microbial biomass.

• Chloride ions inhibit nitrification and are therefore a potential soil biocide.
I can't see from that what the dose rates are, so hard to tell. Chloride will leach readily from the soil, so I don't think low doses are really a problem. Drier areas where leaching doesn't occur as much could be very different though.

I'm with your use of fibrophos, I would do the same. I use compost here, topped up with a little SOP or MOP, depending on how big the price gap is.

Nearly all chemical fertilisers upset biology unfortunately, but unless I went organic I'm stuck with them.
 

York

Member
Location
D-Berlin
MOP is just a salt, no more toxic than table salt. Infact you can buy low sodium salt for the dining table, which is a mix of salt and MOP.

Sodium Hypochlorite is a totally different beast, and I would not want to put it on my chips. :eek:

Sodium hypochlorite is the salt formed by a negatively charged hypochlorite ion (OCl-) and a positively charged sodium ion (Na+). Pure hypochlorite is highly reactive and unstable; therefore, it is usually supplied as a dilute aqueous solution. In solution, hypochlorite eventually decomposes to yield a variety of byproducts including oxygen, chlorine gas, and salt. One of these byproducts, hypochlorous acid, is a powerful oxidizing agent (meaning it can accept electrons from other materials) that lends hypochlorite excellent bleaching and disinfecting abilities. The term "available chlorine" is often used to describe the concentration of hypochlorous acid in solution (which provides a measure of the solution's oxidative ability).
Just a little hint from what a client near Samara, Russia, with Soils >7pH. they use the MOP in the late winter prior to potato planting to get rid of wire worms. Very effective he says.
York-Th.
 

Richard III

Member
Location
CW5 Cheshire
One small thing I consider when working out whether to use MOP or SOP is when the chloride leaches it will take with it the most available cation, which is usually calcium. So for every tonne of MOP used I add on a tonne of lime to the cost.
 

Thedual1

Member
One small thing I consider when working out whether to use MOP or SOP is when the chloride leaches it will take with it the most available cation, which is usually calcium. So for every tonne of MOP used I add on a tonne of lime to the cost.
This is where a MOP/Polysulgphate mix could be an option as is supplies potash, sulphur, calcium and magnesium.

I am a keen follower of Albrecht soil analysis which uses the cations, calcium, magnesium, potash and sodium for calculations. I have created my own copyrighted system that cross checks between RB209 figures and Albrecht. I have a 100% success rate in finding and resolving the limiting factor/factors.

My system not only gives base saturations, but because I use laser soil texture I can define the actual soil type. I can then recommend the correct nutrition program to create the CEC required for the soil type found. My systems gives shortfall/surpluses results all of the following:
Calcium, magnesium, potash, sodium, phosphate, sulphur, manganese, copper, zinc, boron and molybdenum. For grassland it includes selenium and cobalt.

Nutrition is a bit of maze though because if you supply large amounts of nutrients to correct shortfalls, you can end up antagonising other nutrients

As a result I adopt an over and under feeding system, to counteract these antagonisms.

I don't go for expensive muck & magic options for my recommendations, quite often a small change in fertiliser type is all that is required.

My system is not as expensive as some of the Albrecht based companies out there, a good friend of my said they charge a lot of money for very little information, whereas you don't charge enough for the mass of information you supply.
 
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Thedual1

Member
As I have said there is no real problem with light and free draining soils and the chlorine in MOP as it soon dissipates through the soil profile.
The problem is on heavy clay soils and poorly drained ones where the chlorine cannot dissipate through the soil profile.

I stand by my recommending a MOP/SOP blend as it has 50% less chlorine and also delivers 22.5% So3 which is worth £0.80/unit. 125kg/ha will supply 28kg/ha So3 = £22.40 in monetary terms
 

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109: Monitor Farm takeover

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The first episode in the Farm Excellence series of the AHDB podcast focuses on cereals & oilseeds. The Monitor Farm programme comprises a network of farmers from across the UK and Northern Ireland committed to driving innovation and best practice. They host regular meetings at their farms in which they discuss issues facing agriculture in their...
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