Urea VS AN
- Thread starter ajd132
- Start date
- Location
- Lincolnshire
Urea I think requires soil biology to convert into usable forms? So if you've wrecked the biology then it's not going to work so well?
An more like crack cocaine.
Even on our grass which ough have "better" biology we get better growth from an. Cold wet clay so bloomin ages for the biology to get going. Optimum soil biology temperature is loads later than we want to see some decent growth.
An more like crack cocaine.
Even on our grass which ough have "better" biology we get better growth from an. Cold wet clay so bloomin ages for the biology to get going. Optimum soil biology temperature is loads later than we want to see some decent growth.
- Location
- Cornwall
Its quite a complex interaction. AN is, as you say, a salt product so, as the plant rapidly takes up the Nitrate, it has to take up the corresponding amount of water. This means the cells expand as they fill with water and the plant "stands up" as a result. It also means the cell wall becomes thinner as the cell stretches meaning the chlorophyll becomes more visible. These two factors give the illusion of rapid growth and greening. It also means, as the cell wall stretches and becomes thinner, it becomes more susceptible to disease infection and pest damage. The plant can only process the Ammonium and Nitrate at a certain pace regardless of the form it is applied so, all things being equal, the same amount of Nitrogen will give the same growth whether from AN or Urea.
Urea requires Urease enzymes to transition from Urea to Ammonium so the plant can begin to use it. This takes time and requires a soil temp of roughly 7 or 8 degrees. As such it tends to be slower availability and the plant takes it up at a more sustainable pace rather than gorging on Nitrate and water so it has the visual effect of being "slower growing", but it should create DM at the same rate as AN ultimately. Urea does require a certain amount of moisture to wash it in and allow the enzyme to do its thing. If left on the surface, heat can cause volatolisation of ammonia over time, but it needs to be in excess of 27degs for that to be a worry.
That's a bit of a basic run through the process so I hope it makes sense. There are arguments for and against both products depending on the situation but your friendly fert rep is only really interested in emptying his warehouse, so it pays to know the ins and outs. We are pretty much the only country that uses AN in any real quantity, a result of ICI flipping a coin for AN production or Urea production years ago.
Urea requires Urease enzymes to transition from Urea to Ammonium so the plant can begin to use it. This takes time and requires a soil temp of roughly 7 or 8 degrees. As such it tends to be slower availability and the plant takes it up at a more sustainable pace rather than gorging on Nitrate and water so it has the visual effect of being "slower growing", but it should create DM at the same rate as AN ultimately. Urea does require a certain amount of moisture to wash it in and allow the enzyme to do its thing. If left on the surface, heat can cause volatolisation of ammonia over time, but it needs to be in excess of 27degs for that to be a worry.
That's a bit of a basic run through the process so I hope it makes sense. There are arguments for and against both products depending on the situation but your friendly fert rep is only really interested in emptying his warehouse, so it pays to know the ins and outs. We are pretty much the only country that uses AN in any real quantity, a result of ICI flipping a coin for AN production or Urea production years ago.
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Great answer, this is the conclusion i have been coming to. I think many of our problems with weeds pests and diseases is caused directly by this over use of nitrogen in general. Been looking into buffering n applications with humic acids etc (been using straight molasses for a while now), and should theoretically be able to drop total n doses if we can get soil working properly. Soil is just a vehicle for standing a plant in at the moment for most of the U.K.!
If you fancy a project, look at the mysterious world of CULTAN....
NIAB TAG did some work on urea vs AN vs UAN that will be worth a look. No significant differences in yield but some useful discussion comments. Jim Orson's Oracle was one of the more pithy analyses.
Lots of the ammonium is converted to nitrate, so I don't quite agree with all you say there @CornishTone . Out of interest, do you get that blue tinge of nitrate poisoning in wheat after a good hit of urea like you do after a dose of AN and a shower of rain? Your comments about disease susceptibility are absolutely right. We're stuck in a cycle of dependency where high N forces more fungicides and PGRs.
Worth considering in future that urease inhibitors are likely to become a legal requirement in an effort to reduce GHG emissions, no doubt lobbied for by manufacturers of AN like Yara and CF who want to stop bulk global urea holding AN prices down. AN is a material used in WW2 explosives and just a way of finding an alternative market for it after the war.
NIAB TAG did some work on urea vs AN vs UAN that will be worth a look. No significant differences in yield but some useful discussion comments. Jim Orson's Oracle was one of the more pithy analyses.
Lots of the ammonium is converted to nitrate, so I don't quite agree with all you say there @CornishTone . Out of interest, do you get that blue tinge of nitrate poisoning in wheat after a good hit of urea like you do after a dose of AN and a shower of rain? Your comments about disease susceptibility are absolutely right. We're stuck in a cycle of dependency where high N forces more fungicides and PGRs.
Worth considering in future that urease inhibitors are likely to become a legal requirement in an effort to reduce GHG emissions, no doubt lobbied for by manufacturers of AN like Yara and CF who want to stop bulk global urea holding AN prices down. AN is a material used in WW2 explosives and just a way of finding an alternative market for it after the war.
Looked very closely at cultan last year. Even was booked up to visit German farms and manufacturers after the base trip in Denmark but we crashed the car and never made it!
The science behind it makes a lot of sense however logistically and labour wise it is very time consuming.
The AN manufactures should be held accountable for this. Why do we allow ourselves to be led around by the companies.
Sandy
Member
- Location
- Aberdeenshire
- Location
- Cirencester
Been using Urea/Sulphur here for the last 7-8 years and wont be going blue bags ever again. I like the slow release and it's effect on the crop. Less bags needed too, doesnt corrode everything in sight and spreads well.
- Location
- the brecks norfolk
Much the same here. I definitely think the slower steadier growth is a plus and I think that's partly why I can keep dirty varieties clean with a modest cheap fungicide spend.
The down side to urea is getting into the mid set to bring all aplications forward by a week or two and to be able to time applications with weather events, which works on my scale but may be difficult for the big boys.
We've gone a stage futher and putting the S on in early wnter so we can use just straight urea, imvho that needs to go on a bit earlier to get things going in DD so it suits using urea as less risk of washing way, as you say big bonus isnot rusting machines away
What product are you using? Elemental sulphur? Tiger 90?
Yes its a tiger 90 type product sourced via crop advisors comes in 25kg bags which does a hectare in cereals,cant remember the cost a hectare off the top of my head but was a good saving compared to a urea/S blend
What time of year do you spread it? I could never quite find the optimal time to chuck it on
Urea fan here. Used it for 10 years now at least. Crops don't go black green when using it but I don't care.
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when the soil has cooled down I was told, first year I did it mid dec IIRC, would like to do it mid Jan on a frost ideally but if the gound is dry in Dec I wouldnt want to miss the chance
- Location
- Cornwall
You're quite right, like I said it was a basic run through the process. Plants only use a small amount of Ammonium, the rest has to be converted to Nitrite and then Nitrate via nitrogenase enzymes. By starting off with AN, the plant has this nitrate available in relatively large quantities and takes it up quickly whereas Urea starts from a point further up the chain and takes longer for the various enzymes to go through the processes of getting it to Nitrate. As there's more stages, it takes longer and feeds through the system at a trickle rather than a flood... if that makes sense?!
And I've never noticed the blue tinge after urea to be fair. We all forget at times that there is 7 odd tonnes of N sat above every hectare of crops. We just need to get better at extracting it, stuffing it into the soil and keeping it there long enough for the crop to use. Sounds easy aye?!
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You're quite right, like I said it was a basic run through the process. Plants only use a small amount of Ammonium, the rest has to be converted to Nitrite and then Nitrate via nitrogenase enzymes. By starting off with AN, the plant has this nitrate available in relatively large quantities and takes it up quickly whereas Urea starts from a point further up the chain and takes longer for the various enzymes to go through the processes of getting it to Nitrate. As there's more stages, it takes longer and feeds through the system at a trickle rather than a flood... if that makes sense?!
And I've never noticed the blue tinge after urea to be fair. We all forget at times that there is 7 odd tonnes of N sat above every hectare of crops. We just need to get better at extracting it, stuffing it into the soil and keeping it there long enough for the crop to use. Sounds easy aye?!
- Location
- Cornwall
I was told to buffer liquid N with Humic and Fulvic acids as a safener to limit scorch in the heat in Australia once. Seemed to work!
Got a couple organic blokes playing about with Molasses to encourage soil biology after sowing down here as well. Looking forward to seeing the results... if the results can be seen!
I will go against the grain and admit to having gone back to AN this year.
I backed my hunch that following the wettest winter I can remember, would come a dry spring, and late drilled poorly rooted crops.
I am currently still glad that I did.
This thin brash soil is not well served by having the frequently occurring 6 weeks of no or minimal rain in spring, and the misery of watching starving crops looking at urea laid on the surface I can manage without.
Add in busy lambing in late Feb/early March, and it is all too easy to get caught out and miss the necessary rain to wash it in.
I believe that chucking a 90kg/N slug of urea on as soon as you can travel in February, (or as soon as is legal), is the best way to use it here. That way the crop will have enough N available to see it through the spring drought until now.
I backed my hunch that following the wettest winter I can remember, would come a dry spring, and late drilled poorly rooted crops.
I am currently still glad that I did.
This thin brash soil is not well served by having the frequently occurring 6 weeks of no or minimal rain in spring, and the misery of watching starving crops looking at urea laid on the surface I can manage without.
Add in busy lambing in late Feb/early March, and it is all too easy to get caught out and miss the necessary rain to wash it in.
I believe that chucking a 90kg/N slug of urea on as soon as you can travel in February, (or as soon as is legal), is the best way to use it here. That way the crop will have enough N available to see it through the spring drought until now.
- Location
- Cirencester
Yes that is exactly what I do and a neighbor who also uses Urea, we both have found the same, bang a decent slug on early pre rainfall event ideally, has served us well so far.
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