# It All Starts Here For Alfalfa



## Vol (Jul 5, 2009)

From Hay & Forage Grower...

Regards, Mike

http://hayandforage.com/article-322-It-all-starts-here-for-alfalfa.html


----------



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

It all starts here for alfalfa Unfortunately this is not a Universally True. Completely ignoring those of us with calcareous soils. or even Sodic soils.

Alfalfa

Oct. 20, 2015
It doesn't matter where you hang your hat or pay taxes, alfalfa will not grow or be productive unless soil pH is 6.5 or higher (preferably 6.8 to 7.0). According to the Alfalfa Management Guide

No mention is made for the soils that have a >8.0 pH due to high sodium content, or excessive magnesium, or the excessively high calcium levels.

No mention was made for the 8,000 to 9,000 ppm Ca analysis. Nor any mentioning of a 5 or 6 percentage of free lime soil test.

Just as with the Great Truth of a wide swath will dry faster than a nice tight windrow, can be not applicable for some climates, a neutral pH also can be not applicable for some soils.

All in all this is a good article just not universally applicable.


----------



## JMT (Aug 10, 2013)

The article mentioned top dressing fine lime in "rescue mode". What about pelletted lime? Does that work? What are pros and cons?


----------



## Hugh (Sep 23, 2013)

JMT said:


> The article mentioned top dressing fine lime in "rescue mode". What about pelletted lime? Does that work? What are pros and cons?


It will work. A U of Illinois paper from the 1970's shows that as long as some part of a plants roots are in the correct pH, then enough nutrients will be taken in to satisfy the entire plant.


----------



## vhaby (Dec 30, 2009)

The linked article is not quite correct on where to start for alfalfa. Actually, selecting a well-drained, well-aerated soil with a capability classification in the range of I to III relative to slope and erosion is more like the starting point. Once this is done, then a soil test is in order. For acid soils that fit the above categories, collecting soil samples by one-foot depths to at least 4 ft is the necessary second step. If the pH of these depths is greater than 5.5 the soil will be okay for producing alfalfa. If the pH is below 5.5, subsoil acidity, i.e. aluminum and manganese, can become toxic to alfalfa root growth and extension into the soil depth, limiting water uptake during dry conditions. If the surface depth pH is such that the soil needs to be limed to decrease acidity to pH 7 or so, then addition of boron becomes a factor. Liming strongly acid soil to the correct pH for alfalfa, or clover for that matter, ties up plant-available boron in the more coarse textured soils. IMO, one need not do a soil analysis for boron bc the test is not correlated with alfalfa response to applied boron in a 6-inch depth soil sample. On recently limed soils intended for alfalfa, application of 3 to 4 pounds of actual boron per acre should be applied as insurance against possible boron deficiency. Other plant nutrients should be applied pre-plant according to soil test.

Use of pelleted limestone for large scale field application is not an economical approach because of its cost. In addition, limestone pellets limit coverage of the soil surface compared to fine ECCE 100 % limestone, and this coverage is still limited even after the pellets are dissolved by rain and incorporated into the soil. As indicated in the article, correcting soil pH for alfalfa also has to do with Rhizobia fixation of atmospheric nitrogen for the alfalfa. Plant roots growing near the soil surface, in an area that did not receive limestone to correct the pH will not be adequate hosts for activity of Rhizobia, and thus potentially can lead to a nitrogen deficiency in alfalfa.


----------

