# Top Dressing and Urea - How Long Does It Last



## VA Haymaker (Jul 1, 2014)

When you top dress your hay with Urea fertilizer, what is the effective lifespan of it? In other words, you apply the urea, is it absorbed in a few days, weeks, etc. From a growth standpoint, how long it it typically being used by the hay?

What I'm asking, you apply the urea after the first cut, wait for the growth, but don't want to take a 2nd cut until after the urea has been completely up taken and used by the hay - so you get the full effect of it. What is that general time span, 2,3,4 weeks, months, etc?

Just curious.

Thanks!
Bill


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## somedevildawg (Jun 20, 2011)

Here we fertilize every 35 days or so.....Bermuda is cut at 30 days, fields are top dressed after cutting, Bermuda is a heavy user of N. a lot depends on your soil, clay or sand, and the weather. Denitrification, leeching and volotization can all significantly change how much N is available to the plant. What you need to know is when is the best time to cut the forage, ie. when is it mature. Too late and it's rank, too early it could be high in nitrates and low in yield. Hth


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## Tim/South (Dec 12, 2011)

We aim for 3 cuttings so I apply the fertilizer of choice after new growth from the first cutting. Mostly so I can see my tire tracks.

I expect to get 40 days out of my nitrogen. If that holds true and I cut the hay 25 days after applying the fertilizer then it will give the third cutting some boost.


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## Tx Jim (Jun 30, 2014)

Clay coated Urea is advertised as being more stable down here where I live.


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## slowzuki (Mar 8, 2011)

If you are talking about volitization ie the nitrogen leaving in the air instead of going into the plants I think it depends on moisture levels too.


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## Vol (Jul 5, 2009)

Under my normal conditions, it works out to about 6 weeks here....about like Tim/South.

Regards, Mike


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## hay wilson in TX (Jan 28, 2009)

Somedevildawg

The information I get from Georgia says expect 12% CP cut on 6 42 days intervals.
Most of the time I have 12 to 14% CP.


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## Hugh (Sep 23, 2013)

Depends on many things. For example, if you have sandy soils and a lot of rain, the N may leach past the roots very quickly. On the other hand, if you have clay or high organic matter levels the N will move slowly. Soil temperatures and plant metabolism matter as well. I believe you will need to learn by experience, unless you can pick the brain of a nearby producer with similar soils, crop, etc.


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## somedevildawg (Jun 20, 2011)

hay wilson in TX said:


> SomedevildawgThe information I get from Georgia says expect 12% CP cut on 6 42 days intervals.Most of the time I have 12 to 14% CP.


We never get 6, well sometimes we do but the first cut is usually about 40% Italian ryegrass....damned pest as far as I'm concerned.....CP is usually around 11% -13% for Alicia, 13-17% for T-85, T-44 a little better than Alicia but not much, supposed to have better digestibility but it seems to look the same coming out of the south end of the northbound horse.....we cut n 30 day schedule, weather permitting. I know one feller that cuts every 30 whether its raining or not


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## SwingOak (May 19, 2014)

What rate do you guys use for urea? I've been putting on 100 to 150lbs/acre.


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## Hayman1 (Jul 6, 2013)

I typically apply 60# actual N/ac with about 24# S as a combination of Ammonium Sulfate and Urea when I top dress. Went to 75# N this year after first cutting as we had plenty of moisture in the ground and were getting adequate rainfall for distribution and utilization of the N. Just top dressed three fields the other day with 60# as we will be cutting in 30-40 days while we can still make decent hay with Sept weather. October gets tough here most years.


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## SwingOak (May 19, 2014)

Thanks, it's been pretty dry here lately, although we've had a couple of inches of rain in the last week. My fields clearly need some N if I'm going to get anything for second cut.


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