# sulfur and alfalfa



## FranchiseFarms (Nov 16, 2014)

Ok guys been doing alot of reading on establishing alfalfa stands and what I'm gathering is that sulfur plays a key role in its growth. I've read that thick stands and require as much as 100# per acre per year. Anyone with a vast knowledge of alfalfa care to give me some insight


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## Vol (Jul 5, 2009)

Depends on your locale as for your needs.....here I add 5-10 pounds per acre every few years...a little sulfur here goes a long way. Soil testing with recommendations are best. You will also need to add a little Boron when establishing alfalfa.

Regards, Mike

https://ag.tennessee.edu/spp/Pages/soiltesting.aspx


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## PaCustomBaler (Nov 29, 2010)

I agree with Mike. Most soils these days need sulfur because of the tighten emissions and less acid rain. Best way to determine sulfur amounts are to tissue test. Also, 2 lbs of actual boron/ac/year.


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## FranchiseFarms (Nov 16, 2014)

Thanks for in info gentlemen.... I know here my coop carries pure sulfur in 100 pound bags that I can buy and add to my bulk n/p/K to be spread. Does the boron come in bags like that or does it come liquid to be sprayed?


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

Send off a hay sample to be tested for Minerals.

Look at the N/S ratio. If the ratio is 16/1 you are fat. If the ratio is 8/1 you need to add Molybdenum to pull in Nitrogen from the air and make it avaliable to the alfalfa.

A usual hay analysis does not mention Sulfur. It will mention CP not N. I buy a plant analysis so it reports N% not CP. To find CP multiply the N % by 6.25 to find the CP.

Rememper a hay analysis will report for the full plant not the top third you usually see in a tissue analysis.

The big thing is you need to save most of the leaves. So pay attenion to the amount of leaf shatter.


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## hog987 (Apr 5, 2011)

FranchiseFarms said:


> Thanks for in info gentlemen.... I know here my coop carries pure sulfur in 100 pound bags that I can buy and add to my bulk n/p/K to be spread. Does the boron come in bags like that or does it come liquid to be sprayed?


Elemental sulfur takes time to break down to become plant available. Different climates vary in the amount of time. Here at my location they figure about half of what is applied is available that year. Even recommended to apply late summer early fall to get most benifit next year.
I have been applying 20 pounds per acre per year. To get close to a 10:1 ratio of N:S my feed tests say I need 10-15 more pounds of S per acre. Iam still trying to figure out what the best option to apply this extra S is. I can get 4 different types of S from 3 different places. Not each place carries the same supply. These are elemental sulfur. AMS. Potassium sulfate. Gypsum. If your low in Mg you could even consider some epsom salt.


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## TJH (Mar 23, 2014)

If you want to know exactly what to put on your land, send a soil sample to Kinsey Ag in Charleston, MO. and you will get back recommendations that will make your jaw drop on what is needed to grow your alfalfa. His instructor and mentor was Dr. William Albrecht and he is good. KinseyAg.com if you want to check it out.


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## Hugh (Sep 23, 2013)

I doubt 100# per year. If you cut 10 tons per year, you will remove about 40# of sulfur per year. 6 tones per year would remove about 25 pounds of S. (think 4-5 lbs. of S per ton per year) If you haven't done a soil test, I would say learning the PH is far more important.

For alfalfa, get the Ph to about 7 before you worry about anything else. The reason being is that alfalfa plants have a symbiotic relationship with a bacteria that inhabit the roots and these bacteria supply nitrogen to the plants. Below a Ph of 6.5, these bacteria have a low survival rate.

A good soil test will tell you about the Ph, (you may need lime) and then the other nutrients you need to apply. Think of the nutrients as links in a chain. If the soil is low in any nutrient, then that is the weak link and that low nutrient will limit your production. I would follow TJH's advice and use the lab he mentions in the above post.


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## Hugh (Sep 23, 2013)

P.S to the above. Boron can be extremely toxic. Overuse can kill your plants.


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## FranchiseFarms (Nov 16, 2014)

The attached file is a copy of the soil results I got from the University of tennessee. They are not very detailed.i have heard that the buffer pH will be different than the actual pH but don't know by how much and if it will be lower or higher. This field has never been worked or taken care of until I got it. It has had a total burndown and will be sown in forage Pease and triticale this spring to control the weeds, help loosen soil compaction and to increase organic matter as well as add nitrogen. So break it down and tell me what you buys think.


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## vhaby (Dec 30, 2009)

Reply # 6 left out KMag/ potassium magnesium sulfate. 0 - 0 - 22 K2O - 10.8 Mg - 22 SO4 This is a good source of potassium, magnesium, and sulfur that doesn't lower pH as elemental sulfur does.

Regarding boron, unlike clover, alfalfa is quite tolerant of boron. I apply 4 lb of elemental boron per acre to alfalfa on limed acid soil. Liming acid soils ties up what little plant available boron is in our sandy soils. In one of our research studies, application of 3.75 pounds of elemental boron per acre on a well-limed soil increased alfalfa dry matter yield by 2 tons/acre.

Also, liming these soils makes molybdenum more available. As hard as it is to find fertilizer boron in these parts, try finding a company that carries molybdenum. We could not get a response of alfalfa to applied molybdenum on one of our limed acid soils, but that was here.


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## Hugh (Sep 23, 2013)

Looks like your Ph is real low, and they are recommending 2 tons of lime per acre. Alfalfa is a legume, so you don't need nitrogen. They are recommending 90# of phosphate and 90# of potassium per acre. I would use muriate of potash and triple superphosphate. Muriate is 60% potash so you will need 150# of that per acre. Triple superphosphate is 45% P so you will need 200# per acre. I would also give the U of Tenn. a call to double check with them on rates and timing.


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## Vol (Jul 5, 2009)

FranchiseFarms said:


> So break it down and tell me what you buys think.


Just follow the recommendations that Deborah Joines made for you of 2 tons of lime per acre along with 90 pounds of Phosphate and Potash each and you will be much further ahead. She knows what you need for HERE.

Regards, Mike


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## Hugh (Sep 23, 2013)

Consider working in the phosphate. You can broadcast it and then disk it in or till it etc. Phosphate travels slowly through the soil so top dressing is not the best way to get it to the root zone. You could put down the lime, Potassium and phosphate all at the same time and then work all of that in the top few inches of soil.


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## PaCustomBaler (Nov 29, 2010)

I agree. K is a slow mover, someone correct me if I'm wrong, but I believe K only moves about 1/8"-1/4" a year. I'd work all of those in....P, K, lime.


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