# Nitrogen Fertilizer for Alfalfa



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

When is nitrogen fertilization of alfalfa beneficial? Almost never!

http://ucanr.edu/blogs/Alfalfa/ Then entire article from California is interesting. 
If you are in a hurry read the 
A copy & paste 
*In summary:* There are some growers who routinely apply large amounts of N fertilizers to alfalfa. This has been especially true in desert soils. In our view, this is a mistake. The science doesn't support it. It's expensive, requires fossil fuels, and isn't necessary. If nodulation (infection with beneficial bacteria which fix nitrogen) is not successful, try harder to solve that problem. It could be an issue of making sure that viable bacteria of the right species and strain is applied successfully to a field (and re-applied if necessary), correcting a soil factor such as low pH, salt, or low molybdenum, or improving irrigation practices so that roots are not as compromised. Some desert growers routinely apply N fertilizers, but if they examine the economics of this practice, it's rarely beneficial. In rare circumstances, application of modest amounts of N to 'jump start' alfalfa growth can assist if the roots are compromised, the plants are young, the soils are cold, or other stresses exist, but this should be looked on as only a short-term mitigation measure, not a routine practice


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## R Ball (Feb 26, 2013)

I planted alfalfa / og last fall along with the test results for p, k, boron, and lime. Then hit it with 275# acre of triple 19 early in spring. It all jumped.


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## Vol (Jul 5, 2009)

I wince at the cost of P & K.....I sure as heck am not going to throw N on straight alfalfa....you would have to have money to burn.

Regards, Mike


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## swmnhay (Jun 13, 2008)

*I would find it hard to believe that anyone would put N on straight alfalfa other then what comes along with DAP or MAP*


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## vhaby (Dec 30, 2009)

On the western Coastal Plain, nitrogen on alfalfa had very little effect on increasing yield of alfalfa interseeded into a stand of Coastal bermudagrass in a three-year study, regardless of the rate on applied N.

https://articlesearchdatabase.tamu.edu/tmppdfs/viewpdf_1105_22985.pdf?CFID=6472419&CFTOKEN=bde035fb2ce013b1-D4A61AE1-F78A-9071-C7C0C1C1E354F777&jsessionid=e4303e1f4238a6411efc27766e771556c2c1

The only time one might want to apply a very low rate of N to alfalfa is when late seeding in fall into cold soils. Even then, as indicated in a previous post, sufficient, and probably excessive N is applied if the phosphate source is DAP applied at 100 lb P2O5 per acre.


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## mlappin (Jun 25, 2009)

We use 6-15-40 mainly because we can buy it in 25 ton lots then haul it ourselves. I've never seen a soil test come back suggesting any nitrogen even for a new seeding. Could be that we follow beans with hay when we plant and have residual nitrogen leftover from the soybeans.


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## barnrope (Mar 22, 2010)

When I haven't planted beans or alfalfa on a piece of ground for a few years (coming off corn on corn) I inoculate the bean seeds with a substance that promotes nitrogen forming nodule development. Is there a similar product used on alfalfa seed? Maybe it is not needed for alfalfa?

A healthy, well established legume plant will produce all the nitrogen the plant needs and will add extra to the soil.


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## askinner (Nov 15, 2010)

barnrope said:


> When I haven't planted beans or alfalfa on a piece of ground for a few years (coming off corn on corn) I inoculate the bean seeds with a substance that promotes nitrogen forming nodule development. Is there a similar product used on alfalfa seed? Maybe it is not needed for alfalfa?
> 
> A healthy, well established legume plant will produce all the nitrogen the plant needs and will add extra to the soil.


The alfalfa seed I buy is precoated with rhizobium, as well as starter nutrients and lime, just tip it in and go. It does have a limited shelf life though.


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## rjbaustian (Oct 16, 2012)

That's because alfalfa is just like soybeans. It makes its own N so to speak. I can't remember the classification the call them...


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## swmnhay (Jun 13, 2008)

rjbaustian said:


> That's because alfalfa is just like soybeans. It makes its own N so to speak. I can't remember the classification the call them...


Legume


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## rjbaustian (Oct 16, 2012)

I think it's something else though.... Shouldn't have slept as much in FFA class I guess lol


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## rjbaustian (Oct 16, 2012)

You're probably right though lol


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## PaCustomBaler (Nov 29, 2010)

N should only be put on Alfalfa at plantings if the soil is cold. I've found out that adding inorganic N to straight alfalfa only decreases the nodule size and the amount of nodules on the roots. It's a little different on soybeans,...soybeans, on average, will produce enough N to grow up to around 60 Bu/ac. Any higher yields need a little bit of supplemental N applied to them. This could be much different for other parts of US or Can. However, I don't hesitate to putting N on Alf/OG stands that are <70% alfalfa.


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