Urea

[CornishTone]

'Sore on land' How so? I was always led to believe it was less acidifying and kinder to soil microbes, than AN. I'm back on AN this year, after 2 years of urea, the decision being made purely on price. I'm already wondering if I'm made the right decision though.

Without going too deeply into the biochemistry of it all... The process of converting Urea to Ammonium increases pH and then the process of converting Ammonium to Nitrate reduces pH, just the same as AN. So at the end of the day there isn't a huge amount of difference, some but not much.

It is fair to say that Urea is kinder to soil and plant than AN. As the plant can't utilise Urea, it has to wait for he conversion to ammonia and Nitrate in order to be able to use the N. this takes time so the plant takes it up slowly.

Because AN is immediately useable the plant takes it up very quickly. However, it can only process N at a certain rate, so it stores it as a salt in solution. This means it has to take up large amounts of water. The perceived rapid growth rates associated with AN are usually just this process of taking up water to dilute the Nitrate. The water fills the cells, which then expand and stretch giving the plant the appearance of growth. The cell walls become thinner as they stretch meaning the chlorophyll becomes more visible and the plant looks greener.

This also has implications for plant health as the thin cell walls are more susceptible to disease.

 

[Forever Fendt]

Is urea an issue spreading amongst livestock?

Don't spill any, I had a blockage on spreader and had a spill of maybe 3 double hand fulls and kicked it about enough as i thought would not burn grass of ,next day 4 dead ewes within 60 ft of this spillage, lesson learnt so will not be doing this again obviously

 

[Kiwi Pete]

Is urea an issue spreading amongst livestock?

In hot weather I would usually apply it before grazing with dairy cows, just a day or two before they went in, and then it wouldn't go 'up in smoke'. I wouldn't recommend going any further ahead than that, in case it was rained in and gave the stock nitrate poisoning.. I have applied it to a paddock with cows in but of course they shouldn't be grazing to the dirt. Sheep- I wouldn't know because I don't know of any sheep farmers applying N.
On say a 4 week round I'd just hit the paddocks grazed in the last week, each week.

 

[Punch]

We apply urea to sheep grazing. Always empty what's left on it. Then it's a little and often type approach.

As said don't spill it in a pile. I think on grass it's not as likely to volatilise.

Went to a maize meeting a few years ago and they were reckoning ok on maize as top dressing early on. 1 chap said if some is lost in vapour maize can take that in through leaf!

As already said avoid high ph soils and dry weather.

How much rain fall to wash it in?
Heavy dew or 5 mm?

 

[ollie989898]

Top dressing maize with N. Whatever next.

 

[czechmate]

Have to say in the dry east, I have switched back to an. Urea has been a waste of time nearly especially on high ph soils. But I would say on the west especially Ireland it would be a good product.

Back in the day when I Ici where deciding to build fert plants it wasn't by incident as it was the more expensive option but an was the most suitable for the uk.

A lot of hot countries place the urea in the soil, not on top

I was growing milling wheat, what 20 miles from you? When I switched to urea, I didn't up the "N" over the previous an years and yields imoroved. I wouldn't look at AN

 

[willy]

I was growing milling wheat, what 20 miles from you? When I switched to urea, I didn't up the "N" over the previous an years and yields imoroved. I wouldn't look at AN

Yes but I bet you weren't brushy limestone.....20 miles is quite a lot of variance

 

[Old McDonald]

Am I right in thinking that Urea applied in liquid form is less likely to be lost to the atmosphere than if it is applied in solid form? My reading of info from various sources, mainly US, suggests that this is so.

For the past couple of years I have applied liquid N as urea rather than solid N fertilisers to trees that are drip irrigated. When previously using overhead spray irrigation I was quite happy to water in solid N fertilisers to replicate rain.

 

[Kiwi Pete]

Am I right in thinking that Urea applied in liquid form is less likely to be lost to the atmosphere than if it is applied in solid form? My reading of info from various sources, mainly US, suggests that this is so.

For the past couple of years I have applied liquid N as urea rather than solid N fertilisers to trees that are drip irrigated. When previously using overhead spray irrigation I was quite happy to water in solid N fertilisers to replicate rain.

In my experience it's worth applying as a liquid if poss. Downside is wind of course (and probably time if you're mixing your own) granules will throw when you've got the sprayer parked up for the afternoon due to wind. But IME far superior results.

 

[CornishTone]

Am I right in thinking that Urea applied in liquid form is less likely to be lost to the atmosphere than if it is applied in solid form? My reading of info from various sources, mainly US, suggests that this is so.

For the past couple of years I have applied liquid N as urea rather than solid N fertilisers to trees that are drip irrigated. When previously using overhead spray irrigation I was quite happy to water in solid N fertilisers to replicate rain.

We sell a lot of dissolvable Urea into the vine yard market to be put out through the drip irrigation lines. All valid points.

 

[Steevo]

In my experience it's worth applying as a liquid if poss. Downside is wind of course (and probably time if you're mixing your own) granules will throw when you've got the sprayer parked up for the afternoon due to wind. But IME far superior results.

I'm seriously considering spreading the centre of fields normally with the spinner as we do currently, but applying the 24m round the headland as liquid 20N homemixed and applied through sprayer. Should save wasting it to the hedge, and not helping the weeds grow into the field.

I can't keep up with mixing and applying as 20N across the whole field everywhere so this seems a logical compromise and trial into liquid. I may also try one field of liquid only.

Also means I double capacity as can spin and spray at the same time.

 

[Kiwi Pete]

I'm seriously considering spreading the centre of fields normally with the spinner as we do currently, but applying the 24m round the headland as liquid 20N homemixed and applied through sprayer. Should save wasting it to the hedge, and not helping the weeds grow into the field.

I can't keep up with mixing and applying as 20N across the whole field everywhere so this seems a logical compromise and trial into liquid. I may also try one field of liquid only.

Also means I double capacity as can spin and spray at the same time.

That should be the best of both worlds then. We had limited sprayer capacity which was an @£$= with only getting 8ha per tank. We Were using a product called LessN which has since had the kibosh. I was amazed at the rate of uptake with the liquid though. The LessN effectively halved the application rate
Not sure if you have coated Urea but it is great stuff IMO. I spilt a little on the lane and it was still there 2 weeks later in summer, whereas regular granules would have been gone in 2 days.

 

[Old McDonald]

In my experience it's worth applying as a liquid if poss. Downside is wind of course (and probably time if you're mixing your own) granules will throw when you've got the sprayer parked up for the afternoon due to wind. But IME far superior results.

We sell a lot of dissolvable Urea into the vine yard market to be put out through the drip irrigation lines. All valid points.

I was amazed at the rate of uptake with the liquid though.

Thanks for the responses. I do not use the boom, but an attachment I made that lets me place the liquid N right along the olive tree lines only and close to the drip irrigation - the idea being that an irrigation immediately afterwards will moisten the soil around the emitters (1 metre spacing) and hopefully increase the efficiency of the application of N. Wind does not affect application that way. I can keep up with the mixing OK.

I use that method as I can vary the amount applied to each individual tree. Two orchards are of different ages and I have had to replace the odd tree too. Heavy yielders last season (marked) or the current one need more N than those carrying lighter crops. I can see the current season's crop as I approach each tree.

I am considering a venturi when I fit an extension of the drip lines to the new almonds next month. All three orchards are irrigated at the same time from one pump, although I can isolated them and irrigate each individually. Takes time though. The problem would be that liquid N would be taken up too quickly by first season almond trees and they could burn. The other drawback, which will not matter in a few years, is the need for different amounts of N for each tree. As they mature it will be more economic (in time and ease of application) to apply the same amount of N to them all through the emitters. I see that as the most efficient in use of N too. Straight into moist soil in the root zone.

 

[Kiwi Pete]

Thanks for the responses. I do not use the boom, but an attachment I made that lets me place the liquid N right along the olive tree lines only and close to the drip irrigation - the idea being that an irrigation immediately afterwards will moisten the soil around the emitters (1 metre spacing) and hopefully increase the efficiency of the application of N. Wind does not affect application that way. I can keep up with the mixing OK.

I use that method as I can vary the amount applied to each individual tree. Two orchards are of different ages and I have had to replace the odd tree too. Heavy yielders last season (marked) or the current one need more N than those carrying lighter crops. I can see the current season's crop as I approach each tree.

I am considering a venturi when I fit an extension of the drip lines to the new almonds next month. All three orchards are irrigated at the same time from one pump, although I can isolated them and irrigate each individually. Takes time though. The problem would be that liquid N would be taken up too quickly by first season almond trees and they could burn. The other drawback, which will not matter in a few years, is the need for different amounts of N for each tree. As they mature it will be more economic (in time and ease of application) to apply the same amount of N to them all through the emitters. I see that as the most efficient in use of N too. Straight into moist soil in the root zone.

This sounds really interesting. What sort of rates per tree, and what makes up your liquid nitrogen (rate per litre)?

 

[yellow belly]

The independent trials data puts the difference between urea and an as negligible for yield but better for margin as urea is cheaper per kg of n

 

[Punch]

The independent trials data puts the difference between urea and an as negligible for yield but better for margin as urea is cheaper per kg of n

Shhh. Don't let everyone know!

 

[Old McDonald]

This sounds really interesting. What sort of rates per tree, and what makes up your liquid nitrogen (rate per litre)?

It is one of those "it depends" questions. I have a self authored Guide to Almond and Olive Production and IPM. I frequently learn something new, especially about almonds, from Claifornian and Australian sites, so it is an going work, but a ready reference for me (and a neighbour) of all the info I have found over the last 14 years. Here are a couple of excerpts since this is easier than typing it all out again:

Almonds should have a maximum application of 30g of Nitrogen per tree per application for each year of establishment. U.S. designation of trees is 1st leaf in the establishment year, 2nd leaf the next, etc. The Almond Doctor site (www.thealmonddoctor.com) suggests restricting N to 90 to 110g a tree as 1st leaf spread out in 4 to 6 applications. Soil tests will reveal whether P and K are also required, but these should be corrected prior to planting so that none is required at 1st leaf. Growth requirements in subsequent years are about 125g N/tree plus crop requirements. If more growth is required an allowance of 150g/tree could be given.

Trees are classified as “mature” at the 8th leaf and the recommended N amount to be applied is 10% of anticipated yield of kernels. If trees are yielding over 9kgs before the 8th leaf then their growth requirements are met in this 10%. If yielding less they should have 100g N/tree in addition to the crop requirements.

The problem with fertilising on anticipated yield is that an accurate forecast of yield is needed as soon as the trees have flowered – they flower before leafing out. Fertiliser applications should start after the leaves begin to appear on the trees, and not before because the tree cannot take up fertiliser before leaf break-out. I prefer to fertilise on the basis of the weight of the previous harvest. A decision should be made before leaf out how much to apply that year. This will be based upon last year’s yield, how much growth is wanted, and whether the trees are still increasing in annual productivity. The decision can be adjusted mid-season if necessary.

Olives - I apply a minimum of 500g N per tree to all fruiting trees and those estimated to have yielded nearly or over 10kgs have N increased to 1kg in the following season. In some years, such as 2015 the full application of N is not made because the trees were not irrigated due to water shortage, and some suffered enough stress to lose their crop.

At higher yields I will use an extra 500g for each estimated 10kgs increase in yield, so that a tree yielding 30kgs will receive 2kgs of N in the following year. 3kgs per tree will be the limit – which would mean the tree would need to have yielded 50kgs the previous year.

I shall review this strategy with more experience.

.........................................

I need to vary the amount of Urea in the mix according to the amount of N I want to apply. I know the quantity of water that I will be applying because I use the same gear and revs each time. e.g. I apply 600 litres to 300 trees in one block, and 350L to 180 trees in another block - near enough 2L a tree again. Easy calculations. Replants, or high yielders have a guesstimated adjustment to the continual travel with the pipe running out the liquid N.

The weather has a big bearing on the number of applications I make in the year and I have to do some juggling to keep up the amount of N I want to aplly later in the season. Timing is quite critical, but too long an answer to post here - it is a very long post as it is.

I use prilled fertiliser early in the season, when the ground is always fairly wet. As posted earlier, I will be using only prilled fertiliser on the almonds this year.

Many places in the world, and some advisers, consider that little, if any, N should be applied to olives. Trials with proper fertilisation show that it is economic to apply N. Requirements for olives are less than for almonds. The olive fruit is all that is removed from the orchard, but the almond kernel, shell and hull are all removed, so additional N and other nutrients are removed with the shell and hull.

This is what I have enjoyed most by farming around the world - new crops, new things to learn.

 

[Kiwi Pete]

It is one of those "it depends" questions. I have a self authored Guide to Almond and Olive Production and IPM. I frequently learn something new, especially about almonds, from Claifornian and Australian sites, so it is an going work, but a ready reference for me (and a neighbour) of all the info I have found over the last 14 years. Here are a couple of excerpts since this is easier than typing it all out again:

Almonds should have a maximum application of 30g of Nitrogen per tree per application for each year of establishment. U.S. designation of trees is 1st leaf in the establishment year, 2nd leaf the next, etc. The Almond Doctor site (www.thealmonddoctor.com) suggests restricting N to 90 to 110g a tree as 1st leaf spread out in 4 to 6 applications. Soil tests will reveal whether P and K are also required, but these should be corrected prior to planting so that none is required at 1st leaf. Growth requirements in subsequent years are about 125g N/tree plus crop requirements. If more growth is required an allowance of 150g/tree could be given.

Trees are classified as “mature” at the 8th leaf and the recommended N amount to be applied is 10% of anticipated yield of kernels. If trees are yielding over 9kgs before the 8th leaf then their growth requirements are met in this 10%. If yielding less they should have 100g N/tree in addition to the crop requirements.

The problem with fertilising on anticipated yield is that an accurate forecast of yield is needed as soon as the trees have flowered – they flower before leafing out. Fertiliser applications should start after the leaves begin to appear on the trees, and not before because the tree cannot take up fertiliser before leaf break-out. I prefer to fertilise on the basis of the weight of the previous harvest. A decision should be made before leaf out how much to apply that year. This will be based upon last year’s yield, how much growth is wanted, and whether the trees are still increasing in annual productivity. The decision can be adjusted mid-season if necessary.

Olives - I apply a minimum of 500g N per tree to all fruiting trees and those estimated to have yielded nearly or over 10kgs have N increased to 1kg in the following season. In some years, such as 2015 the full application of N is not made because the trees were not irrigated due to water shortage, and some suffered enough stress to lose their crop.

At higher yields I will use an extra 500g for each estimated 10kgs increase in yield, so that a tree yielding 30kgs will receive 2kgs of N in the following year. 3kgs per tree will be the limit – which would mean the tree would need to have yielded 50kgs the previous year.

I shall review this strategy with more experience.

.........................................

I need to vary the amount of Urea in the mix according to the amount of N I want to apply. I know the quantity of water that I will be applying because I use the same gear and revs each time. e.g. I apply 600 litres to 300 trees in one block, and 350L to 180 trees in another block - near enough 2L a tree again. Easy calculations. Replants, or high yielders have a guesstimated adjustment to the continual travel with the pipe running out the liquid N.

The weather has a big bearing on the number of applications I make in the year and I have to do some juggling to keep up the amount of N I want to aplly later in the season. Timing is quite critical, but too long an answer to post here - it is a very long post as it is.

I use prilled fertiliser early in the season, when the ground is always fairly wet. As posted earlier, I will be using only prilled fertiliser on the almonds this year.

Many places in the world, and some advisers, consider that little, if any, N should be applied to olives. Trials with proper fertilisation show that it is economic to apply N. Requirements for olives are less than for almonds. The olive fruit is all that is removed from the orchard, but the almond kernel, shell and hull are all removed, so additional N and other nutrients are removed with the shell and hull.

This is what I have enjoyed most by farming around the world - new crops, new things to learn.

Thanks for the info. Really interesting, other than pine trees and piddling on my lemon it's all new stuff to me!