Try mined 'Sulfate of Potash'. Use about 5/8 of a pound per 100sf. It has a fast to moderate release, where Greensand has a very slow release over a long period.

Here is a link that might be useful: Sulfate of Potash

The results you see are why it is always important to have that soil test done before adding "stuff" you may not need and not getting "stuff" that you do need, ie wasting your money, time, and energy on what you did not need. While lime does help correct soil pH it is not either the Calcium or Magnesium that really does that although both provide the catalyst to change the number of free radical Hydrogen ions that cause a low soil pH.
What is the level of organic matter in the soil now?
Adding sufficient levels of organic matter, compost, leaf mold, could be all that is needed to change the amount of Potassium.

Michael-
Thanks for the info and the link.
Looks like sulfate of potash (equals potassium sulfate correct) might be what I need. Seems as though there are mined versions (like you mention) and commercial versions (non organic) that have been altered with acids (not omri listed).

So you're kind of thinking I need to use this until my greensand starts kicking in?

There apparently is also "potassium magnesium sulfate (langbeinite) that can be used, and is readily available to me. Problem is that it is also a magnesium source.

Part of my YARD is magnesium & potassium deficient, but the main part of my yard/garden has borderline sufficient/high amounts of magnesium (around 100 lbs per acte). Wondering if I use the sulpomag, at the rate required if it would take my magnesium levels into excessive? Any ideas?

Kimmser-
Yeah, I understand that soil tests are supposed to be taken before incorporating ammendments, but it just didn't happen as I explained.

Kimmser stated:
"While lime does help correct soil pH it is not either the Calcium or Magnesium that really does that although both provide the catalyst to change the number of free radical Hydrogen ions that cause a low soil pH."

I'm not following what you're trying to say here. Please explain.

Organic matter is extremely low. 2 problems with adding organic matter to try to correct potassium deficiency right now.

1. One of the plots is getting ready to have a winter garden planted now.
2. Older plot (which the test was taken from) is getting ready to be cover cropped.

I am going to be incorporating aged pine bark fines but compost is not available to me. Working on that for next season.

And also incorporating alfalfa meal (with the pine bark fines).

Does sulfate of potash lower ph?

My ph is already low and if this would have a tendency to lower it more, I'm wasting my time trying to find a source.

Sulfate of Potash is not an acceptable organic product.
emyers, you might want to spend some time at the Soil Food Web Primer whihc might help answer some of your questions.

Here is a link that might be useful: The Soil Food Web Primer

kimmsr-
According to what I've read it is acceptable, IF, it is in its natural mined state, has not been modified with oils (to keep dust down) and has not been modified with acids to make it faster reacting. I'm summarizing and interpolating but basically that's the gist. Have found some sources of omri certified stuff based on a link someone on here provided.

Oh yeah, & thanks for the link.

I don't completely understand the situation but I do understand that there is a nutrient deficiency you may need to focus on more than just the N-P-K fertilization method. After doing some reading I have found out that soils that are poor are missing minerals. Although a more expensive amendment to soil if you use a worm casting and kelp meal mixture you can Get all of the 72+ essential nutrients needed for supreme soil fertility.

Also I forgot to mention Worm Castings tend to help maintain sufficient moisture in sandy soils.

emyers,

Greensand, rock phosphate, and granite dust are ground rocks. Over the long term they will release nutrients, but should not be expected to do much of anything the same season you apply them. They weather very slowly... like rocks. Langbeinite and potassium sulfate are salts and rapidly go into solution and are therefore readily available to plants. Both are fair game for organic if the are mined. It is likely that the manure bumped your pH up. 5.9-6.6 is a good range to be in, but keep in mind that soil tests are only semi-accurate and will vary from sample to sample even if nothing has actually changed.

kansastropic-
Thanks for your input. I've looked into worm castings in the past, and it just became too expensive for me, so I started looking into other alternatives. I really like the idea and will probably get involved in some vermiculture myself in the not too distant future.

As far as the kelp meal goes, It's one of those things that I kind of keep forgetting about. Partly because it's also pricey, but it certainly has it's benefit of all the micronutrients that you mentio. I actually started with greensand primarily for those same reasons, but didn't realize it would take longer to work. I think it's time to look into kelp meal again.... but perhaps in bulk from a feed store? I think I asked about it the other week, when I was looking for alfalfa meal, and if I'm remembering right, the feed store was also a source for it. If so, I'll pick up a bag.

fertilizersalesman-
So composted cow manure has a liming effect? Yeah, I'm starting to understand now that the rock powders are slow to release. I actually ordered some of the organic potassium sulfate that I will use to temporarily get my potassium levels up and leveled out.

Wondering if you could clear up one more thing for me...
Rock phosphate is a mined substance also (as you mention). Note that in the original post above, that the only thing I added (I think) that could have increased my Phosphorous levels was rock phosphate. For whatever reason, my P levels went from high/very high to very high/excessive. Do you have any explanation for that? The rock phosphate was espoma and it's texture changed from stuff that I used to get so I called the company. They apparently started pelletizing it (rather than the very fine powder) to make it more usable with drop spreaders etc. Anyway, just wondering if you had insight into why the rock phosphate as a rock powder, changed my phosphorous level, while the greensand as a rock powder apparently didn't seem to move my potassium levels.

Of all the things on a soil test, P is probably the least accurate so I wouldn't put a whole lot of weight on the exact number. Change in pH, temperature etc affects P availability, and certainly the rock phosphate had an effect. Different rock sources have different levels of solubility, and if Espoma is grinding it fine that would make it more available.

And thanks again...

To expand a bit on what fertilizersalesman said about phosphourus, it is difficult to make any kind of P adding recommendation given that P is nowhere near as important to plants as it was once believed to be and the lab making recommendations may be using old info on what amount is required or newer info.

My personal opinion is that the NPK way of looking at things is fundamentally broken. This doesn't just apply to organic gardeners, but even 100% synthetic commercial agriculture has for decades placed more importance on P that appears to have been wise.

To this day one can find high P fertilizers promoted as bloom inducing when it is not at all true.

Best I can tell the reason folks got so concerned about P is that it generally isn't very available in mineral soils in cool weather. To deal with the lack of P availability in cool soils folks got the idea that they should dump a lot more P on their soil so that the amount available would hopefully increase. This then led to the erroneous idea that high P was a good thing to get plants flowering and producing.

More recent research suggests that most plants will use less P over their lifespan than they will calcium and sometimes magnesium (the ingredients in lime).

To me this breaks the entire NPK concept and if we really want to over simplify plant nutrition we should replace NPK with N-Ca-K at a minimum.

The good news is that in many cases elevated levels of P (such as is common in my state and certainly common in my yard) are of no real consequence because it suffers from availability problems in my northern, cool soil garden. So, even though P is elevated in a soil this doesn't mean a plant will get an excessive amount of it.

We could discuss other nutrients and the common misconceptions of them, the reasons why amounts lower or higher than a soil test recommendation may or may not be important, the role of pH and how critical it is or isn't etc, but let's not :)

As has been mentioned numerous times if you wish to pursue organic methods to growing things, please release your mind from NPK and pH. Start by adding organic matter and then see how things go. High amounts of organic matter in a mineral soil neatly resolve most (but not all) problems related to soil chemistry issues.

It (organic matter) is the starting point.

Settle down there justaguy, lets not get crazy. The problem with P is that the amount in the soil does not give a good indication of how how much is available to plants. Soil testing tries to account for this but is only partially successful which are why you should look at your soil test results with squinty eyes.

As far as how important P is, it is vitally important. Just like all the other essential nutrients. NPK are singled out because they are the ones that need to be added to soil in the greatest quantities to maintain good growing conditions. But they are not any more important than nutrients like boron which are only needed in tiny quantities, if anything is deficient plant growth is inhibited. P is added in large quantities not because plants need a whole lot, but because it reacts in soil forming relatively unavailable compounds.