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Coldwater, Michigan | Last question first. Why do they add salt to fertilizer? Salt primarily comes from the nitrogen content and the potash content of a fertilizer. It is in some of the other compounds, just not usually as much. In the case of Potash, originally we were talking about wood ash "Pot Ash", very caustic (I don't know whether that would have qualified as "salt" or not. As we usually use it Potash somewhere around 0-0-60 to 0-0-62, is near the form it was taken from the ground and is a KCL(pottasium Cloride) element. The Cloride is the salt part of the product. There are other Potassium products that supposedly have lower salt content. Possibly pottasium sulfate, or Sul-Po-Mag (K-Mag 0-0-22-11-22).
If you were to remove the cloride fom the Pottasium such as in the process of Pottasium Hydoxide, you achieve a nearly salt free product(KCL-CL+H20= approximately KOH). It takes some elaborate processing to accomplish the feat, so the price is considerably higher.
With Nitrogen NH3 isn't a particularly high salt product in and of itself. Reacted with water you get Aqua Ammonia which is a very low salt product. Partly because it is in dilute form. Urea which is normally next in line is quite salty. When they were making it with formaldihide(sp?) in order to harden the prill, it was possibly even saltier. I don't really know on that one. 28% is very salty.
Some seed placed starters have lowered the potash content in the mix in order to claim low salt. One I know of even uses KCL in their seed placed starter and can claim "low salt". Most low salts come from the KOH potash. Either Urea or 28% used in a seed placed starter will be unsafe at higher rates of use, not just because of the salt, but because of the Urea contained in Both (Urea and Urea ammonium Nitrate (28%, 32%, etc)).
What makes Urea unsafe at higher rates, dry soils, or light soils, is that Urea drives the soil Ph to extremely high levels for a short period of time after contact with moisture in the soil. This can cause seed burn or even seed death if too high of rates are used. Or if the soil is extremely dry at planting. Sandy soils are generally worse than are the heavier soils.
If a seed placed starter has some potash content, and the nitrogen is as high as 7-8 you can bet that it has some Urea in it. That's why with some seed placed starters, such as a 6-24-6, 3-18-18, you can safely apply up to 5 gallons (in some cases even more), and with others such as 9-18-9, 8-19-3, 9-19-3, and some others, you could easily damage you corn seed with rates as high as 3 gallons.
There are exceptions to what I just told you but those are generally true. If you are planting in medium or heavier soils you can often "get away with" higher rates of these unsafe products, but wait till you get dry soil at planting that persists for a couple of weeks. Put a yield monitor on it if you must to see the difference. Many people then cuss the seed placed salesman, and often he is at fault.
This is one of my concerns with the increased usage of Urea I see in the midwest for corn: the potential for damage to the corn seed from this urea affect. It was bad enough a couple of years ago that Purdue had an article on their website talking about Urea Hydrolysis. If Urea alone can do this, let's make it even worse by adding a seed placed starter that contains Urea! One is bad enough, the two combined may be enough to finish the job.
Let's add one more here: suppose he has used Urea broadcast, then a Urea based seed placed starter (already a hot spot), then he uses a "Squeeze pump" to meter the fertilizer. Squeeze pumps have a habit of surging. More product gets delivered just ahead of the rollers, less product after the rollers. If the above mix is aready hot, what do you have if you delivery system increases the product delivered to that foot of row? Even worse! Picture included.
Some crops are much more sensitive to this affect than is corn. Most bean crops, Sugar beets, sweet corn, and others can be much more so than corn. On the other hand, wheat generally tolerates the Urea and salt fairly well. But Barley does not! Have to know your crops.
Man this thing has gotten long. I haven't gotten into how I feel the seed placed products should be sold, but I think you can already get the idea that I don't fit the normal sales person either. These are some of my concerns when I walk onto a guys farm, even before he has a chance to ask me "what are you selling". I'll post about the selling later today, if there is an interest.
Edited by Bill Moyer 11/11/2006 15:13
 (Squeeze pump -best2.jpg)
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 Squeeze pump -best2.jpg (56KB - 197 downloads)
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Tell me about liquid 6-18-18 fertilizer
