If no one gets to you in a day or two, I'll get back to you.

Observation and Question: A TEC of 15 indicates a silty loam and is sometimes a low end for clay. What is your soil like? You should do a jar test.

The top four inches of soil are black with a lot of sand... at about 5 inches, it;s almost pure white sand. I had to make sure I only pulled up the first 3-4 inches when getting my samples. Most of the land around me had "sugar sand" on it before the homes were put in. It's a really soft type of sand that a car can get stuck in if you drive on it. Overtop they usually put down some black soil and the grass.

Your resident soil analysts on leave? I'm just visiting from another forum, but I have some time tonight so I'll give you my take.

Sample Depth:
4 inches, perfect. The recommendations below are for that 4 inch depth.

Total Exchange Capacity: 15 falls into a silt loam, even a silty clay
range I think this may be inflated by the an amount of free calcium in your soil. A TEC of 10-12 may be more accurate, but it's not critical for our purposes. It is still a good number that will hold decent
amounts of nutrients.

pH: 7.5, moderately high, higher than the ideal 6.8 but will not be a detriment to an attractive
lawn. Use of synthetic ammonium based nitrogen fertilizers can help temporarily lower this and may make some dent long term, but don't bet on that.

Organic Matter Percentage; 4.76. A very nice place to be normally. I suspect the OM has quite a bit to due with your sandy soil's TEC. On sandy soils, OM in excess of of 3% can create drainage problems. Just a heads up, not an issue otherwise.

Sulfur: 17 is safely above minimum levels.

Phosphorous: 172 lbs/acre reported as P2O5. Right smack in the middle of optimum levels. Good place to be. Optimum levels would be between 138 and 230. I would recommend that you let this ride until a future test shows a drop. Your OM should be a sufficient source. You don't need to avoid a P source, and if you do add any- keep a record, but I advise against it.

Calcium: More than sufficient, although I believe it is skewed to the high side.

Magnesium: 78. Very low. Deficient. Isn't this quaint. I no more say that the skewed TEC shouldn't be a problem and now this. You should get an enhanced pH ammonium acetate test on your soil so you have accurate base cation numbers to work from. From here on out, to be safe, we shoot for minimums rather that optimums. This needs be raised to above 120. Ideally it would be nice to be above 280 here. But that's dreaming. The most common source for magnesium is Epsom Salt. The problem? It's a Salt. So it needs to be applied judicially. It should be applied at rates no greater than 2 lbs per application with each application 90 days apart. In Fla. you can do 4 a year. Always try to avoid applying it within 2 weeks of a synthetic N application or within 2 weeks of any other high salt amendment like potassium chloride etc.

Potassium: 35 Very low. Deficient. Ditto above. We're going to splurge a little here a shoot for about 220. Apply 6 pounds of potasium sulfate (sulfate of potash) SOP. Avoid applying within 2 weeks of a synthetic N app or an app of Epsom Salt. The more gap the better. Avoid applying more than 3 lbs in any one app and avoid more than 2 lbs in an app during the hot summer. As you are in Fla, if you can separate the K app by 6 weeks from any other app, you could make a 4 lb app in winter. (Decemberish?) So 2-3 lbs early this spring, then your choice on the other 3-4 heeding the restrictions.

Sodium: Within the acceptable range.

Trace Elements: Aluminum is not at issue.

All other trace elements appear at or above recommended levels but nothing that should be detrimental. You've got enough on your plate. No sense stirring the pot.

I think I'm done with doing recommendations on this forum unless they are easy and the residents don't do them. :/ :)

I've been reading Bill McKibben's book "The Art of Balancing Soil Nutrients" to try to make from tails on a soil analysis. Here's what I understand based on my reading so far

Magnesium and Potassium are the big problems. Could I fix both with a starter fertilizer or should i find some KMAG (potassium magnesium sulfate) and put that down?

I've got high calcium, and nothing is to be done about that due to the high amount of coral sand in the soil. I think that also. Drives the Ph up... not going to sweat it, St Augustine grass will handle this ok.

Manganese is low - do I really care for grass? A chelates manganese as a foliage feed is what is recommended to fix this, just not sure that I need to worry about it as I'm not growing a nutrition crop.

I just realized a starter fertilizer isn't an answer... that's got high phosporus, not the potassium I need

Hi Dave. I'm no expert but I have learned a few things in this forum:

Magnesium is low and is best raised by using epsom salts (MgSO4). I don't have the application rates for you as I haven't done those calcs before. I probably could figure it out, but I'm sure others like ridgerunner already have the formulas handy.

Potassium is also low and can be remedied with potassium sulfate 0-0-50. This is a little hard to find and a little pricey. I think I spent about $40 on a bag and another $35 for shipping, twice. But, if you can keep your CEC up you might not need to add more for a long time. You can google around for potassium sulfate for lawn care. Also see if any local gardening/lawn centers will order it for you.

When you add these minerals it will kick off some of the calcium and lower that value a bit. But, like you say, if you have a calcium based sand it will probably always be an issue. The calsium in and of itself isn't a problem, it's just that your pH will tend to be high. Just continue to add clippings/leaves (if you get any down there) and anything else organic to mulch in. The more organic matter you can get into your soil the better your CEC will be, and the more minerals your sandy soil will be able to hold onto.

I would personally use milorganite instead of Scotts as it is organic, and really only adds nitrogen to your soil (plus some iron, which is hard pressed to get used anyway at your pH). I don't know the application times for milorganite for southern lawns, but it is difficult to hurt a lawn with milorganite. You could search this forum for "milorganite St. Augustine" and see what you can find. If you have your P and K levels where you want them you don't need it from Scotts.

I'm sure others might have a slightly different take on things, but you won't go wrong with the epsom salts and the potassium sulfate.

I just realized a starter fertilizer isn't an answer... that's got high phosporus, not the potassium I need

Nope. :)

That leaves the Mg and K question: Kmag is fine. It is essentially nothing more than a mixture of SOP and Epsom Salts. I don't like it for two reasons. One is that I don't particularly like all the math required to calculate application rates of applying products containing two amendments and to a lesser extent because K will inhibit the grass uptake/use of Mg., not that applying them separately is all that big of a counter measure. Salt index is about the same (Epsom and potassium sulfate is actually mid-range, but salt index is something to keep in mind especially in hot drought times.), so no advantage there.

And

The Mn. question. Yes your Mn is a bit low, >30 would be desired, but as I say, Trace elements very seldom result in turf issues. Grass is very forgiving. Adjustment is totally up to you, follow manufacturer directions carefully for application rates.

Thanks Daniel and RIdgeRunner.... I'll work on figuring out the K and Mg additions this week.

Ridgerunner, I got an email on another post you made, but I don't see it here. Not sure if you deleted it or if Houzz's forum software glitched and didn't save it properly.

Double check me here... an acre is 43560 sq feet. So the pounds of a admendment that I'm short for an acre, I'd just divide that by 43.56 to the the right number, correct? For example, I'm short 276 lbs/acre for potassium. That means I need to apply 6.33 lbs per 1000 sq feet. If I do over three apps this year, thats about 2lbs per 1000 sq ft each app. Does this make sense?

I've read that for potassium I need to apply 2x to get the uptake value (If I'm short a pound, I need to apply two pounds)... is this correct?

Ridgerunner, I got an email on another post you made, but I don't see it
here. Not sure if you deleted it or if Houzz's forum software glitched
and didn't save it properly.

Nope. I didn't post and delete the post. It's my understanding that you will also get notified if a post is edited, I have edited posts in the past, but I don't recall doing that on this thread.

276 lbs of elemental K would require the application of 6.33 lbs per thousand square feet. Correct. To apply 6.33 lbs of of elemental K via SOP you would need to apply 12.66 lbs of SOP product per thousand square feet as every 1 lb of SOP only contains 0.5 lbs of elemental K. Correct. If you were to substitute MOP (potassium chloride) for SOP you would need to adjust the amount of product because potassium chloride contains 0.6 lbs of elemental K for every 1 lb potassium chloride product.

There is a good reason that I suggested that you only try to adjust to 220 lbs at the most for elemental K. I apologize if my figures may have confused you.

220-35=185lbs elemental K. 185/43.5=4.25 lbs of K needed per thousand square feet. 2X4.25 ( to determine the amount of SOP product needed per thousand square feet) =8.5 lbs of SOP per thousand sq. ft. So why did I advise 6? I decided to be even more conservative. 165.5 lbs of K per acre is well above bare minimum levels of 80-100lbs per acre and if my concern is unfounded (not likely) you still would be at 2% of base saturation (see soil report recommended % range for K).

Clear as mud?

My concern is that your reported calcium levels (and maybe your Mg) is significantly over inflated. That would result in an over inflated TEC and skew base saturation percentages. If we base our calculations using these inflated numbers, there is a very real possibility that we can create soil imbalances which could be very harmful to your turf and the world could end.

So 276lbs? I strongly advise against it.

Confused? I wouldn't blame you. If you want more clarification, please feel free to ask.

@ridge: What do you think about magnesium? I notice in rereading some of morpheus' old lab recommendations that he does not seem to account for actual % of something like K in SOP. For instance, he might take the 276 and divide it by the 43.56 to get the 6.3 lb per thousand. Split that into maybe three applications of 2 lb/k each. I realize this will apply only half of your recommendations, but I know morpheus was aware of the difference. I'm thinking he was conservative in his recommendations, not wanting to change anything too quickly. SOP is water soluble and will go into the soil easily, so maybe that has something to do with it.

Also, the potassium should be applied before rain, or it should be irrigated.

As far as the Mg goes, by morpheus' rates, David would need 5 lb epsom salts per thousand sf, which would raise his levels conservatively, requiring more the following year, after another test.

EDIT: Somehow I missed ridge's full recommendations early in this thread, so ignore my numbers and just do "what he said." :O)

daniel,

:)

Every app of any amendment should be watered in and regular, at least weekly waterings should be made. I've got to remember to state that when I'm giving recs. Another thing I noticed upon review is that I don't make clear is that no more than three of four applications a year should be made and they should be spaced as far apart as possible 60 to 90 days. I usually try give total deficiency and the total amount for the year, but I need to watch my p's and q's. Thanks.

As far as the Mg goes, by morpheus' rates, David would need 5 lb epsom
salts per thousand sf, which would raise his levels conservatively,
requiring more the following year, after another test.

5lbs? To satisfy David's total Mg deficiency? or do you mean 5lbs Epsom is the max to apply in any one year?

Could you link to one of the posts that you are referencing. I'm pretty sure he calculated % elemental content in a product when giving recs. (he just may not have revealed how the sausage was being made).

@ridge: sure, here's one example, but I've looked at several and they all follow the same calculation pattern:

http://forums2.gardenweb.com/discussions/3893411/logan-labs-soil-test-results-advice-high-phos-low-nutrients?n=12

In this case the test shows a K deficit of 255 lb/acre. 255/43.56 ksf/acre equals 5.85, call it 6.0 lb K/ksf. morpheus recommends two apps at 3 lb each. There are many examples of this, including a Mg deficiency of 93 lb/acre. His recommendation is for 2.0 lb/ksf split across 4 applications.

Using the same formula for this thread, Mg is short 209/43.56 which equals about 5 lb/ksf. I know this is low assuming Logan is reporting Mg as elemental. As a side note, potassium is often reported as K2O, but I'm assuming from your analysis that Logan reports deficiencies in elemental K.

I really am not qualified to do a full test as I do not consider the interactions of different applications, but adding K seems pretty simple and harmless.

Thanks for the link.

In this case the test shows a K deficit of 255 lb/acre. 255/43.56
ksf/acre equals 5.85, call it 6.0 lb K/ksf. morpheus recommends two
apps at 3 lb each.

You couldn't find an example that wasn't a complete disaster? It's hard to
determine why he made the K recs in that case. It's not aggressive but
it's certainly not terribly conservative. See if you can find one where K
is the only or nearly only deficiency. That will give you better
insight into his analysis and recommendations. I can assure you that he doesn't determine recommendations simply based on dividing a deficiency by 43.5.

There are many examples of this, including a Mg
deficiency of 93 lb/acre. His recommendation is for 2.0 lb/ksf split
across 4 applications.

I understand that you may have found a pattern, but, once again, I assure you that he doesn't determine recommendations simply based
on dividing a deficiency by 43.5. Soil test analysis is not that simple.
Give him some credit.

Using the same formula for this thread, Mg is short 209/43.56 which
equals about 5 lb/ksf. I know this is low assuming Logan is reporting
Mg as elemental.

This is where your theory fails. Above you found that 93 divided by 43.5 is approximately 2, so the application rate is 2lbs/ per thousand. How did he come up with the 4 apps? why not 2 or 3? Here, by employing your theory, you come up with 5lbs. spread over 4 applications? or is it 4 apps of 5 lbs each? You may want to consider that this is surface application on an established lawn and 2lb applications, although a bit conservative, is the max rate recommended. so no matter what the deficiency, as long as it is greater than 43.5 lbs per acre, the recommendation is going to be 2lbs per thousand 4 times a year.

As a side note, potassium is often reported as K2O,
but I'm assuming from your analysis that Logan reports deficiencies in
elemental K.

Yes. If the label states potassium or K, I assume it is the elemental form. Where have you seen a soil test that reports K2O?

Edit: However, if you are referring to the use of K2O when stating K content % of the various types of potash, I don't know why it is used as the standard or why it is used interchangeably with K, the elemental form. For instance: As I'm sure you are able to calculate, elemental K is 52% of the (molecular) weight of KCL (potassium chloride). So a 100lb bag of potassium chloride would contain 52lbs of elemental K. However, the bag of KCL lists the contents as 60-62% K2O or K (and we treat it as 60% elemental K in soil amending). How is that? 52% of 100lbs is 52lbs of K not 62% !!!!. 83% (the amount -molecular weight- of K in K2O) of 100 lbs of K2O is 83lbs of elemental K. 52lbsof elemental K ( the amount in KCL) divided by 83lbs of elemental K (the amount of elemental K in K2O, the standard for some reason) is 0.62. So any given weight of KCL is the equivalent of 62% of K2O and it is accepted that that is the elemental K content of KCL. Why this conversion is used, I have no idea. Nor do I have any idea why we accept this conversion to represent the elemental K content of a bag of KCL (or any other potash source) for soil amendment adjustment. I know I fudge it to avoid having to have this conversation each time a K rec is made.

I really am not qualified to do a full test as I do not consider the
interactions of different applications, but adding K seems pretty simple
and harmless.

That's vaguely accurate to a point, I guess. True if you're comparing it to lbs of Boron, not so true if you compare it to lbs of alfalfa or maybe gypsum.

daniel,

Ok. You're a clever guy. Eventually, you are going to back me into a corner and expose my areas of ignorance. Cut me some slack. You're more of an investigator- interrogator than engineer. Why are you wasting your time here? You really should join this site: Those folks are more your peers than I and much more likely to be able to answer your questions. Besides you might be able to help them challenge some of the "know it alls" that give morpheouspa and andy10917 a hard time.

Registration for membership is at the top left on the linked page.

I just opened this post on my computer, and see the post you made Friday that starts "Your resident soil analysts on leave?" - over this past weekend, I was looking at this post several times on my iPad, and it never refreshed. Very weird. That's why I posted that I had received an email but couldn't see a post. Sorry about that... silly technical glitch of some sort.

I'll have to look at this tonight and dig into the recent dialog, as I missed all these posts over the weekend for some reason.

Thanks everyone!

@ridge: I'm sure you're correct that there is more to it than dividing by 43.56. Now that I've found out where morpheus has been hiding I'll ask him what his thought process was. This reminds me of that insurance commercial where Lucy from Peanuts keeps telling the guy she wants to charge 5 cents. He finally says, "Everything can't be 5 cents"!

As far as the epsom salts, I was saying that using the morpheus example, David would need 5 lb epsom salts. I did not foray into the timing or number of applications to get the 5 lb. In morpheus' case, he recommended 2 lb total and split it up into four applications of 0.5 each. I didn't do that as I'm not sure about interaction with other things he needs to do, etc.

Engineers are interrogators, it's kind of in the job description. I've changed careers, but will take your comments as a compliment. I did join that other site yesterday. Hmm, you're not trying to get rid of me, are you? :o)

RIdgeRunner and Daniel... thank you both for the comments - they are educational for everyone, and sorely needed by me. Before my note above indicating I realized there was a post from RIdgeRunner, I called Logan Labs first thing this morning.

They clarified something I wanted to share with everyone. The lab recommends that if the soil is 7.4 or higher in PH that the ammonium acetate test is run, as RIdgeRunner mentioned. The reason is the standard test uses an acid reactant that is about a Ph of 2.4. For high Ph soil, it skews the testing. Another issue is the high calcium content, which the acid will end up dissolving and causing an indicator of a higher soluable calcium level than really exists.

Logan Labs also gave me Bill McKibben's number, so I rang him up. He further explained that when the soluable calcium numbers are whacked in the standard test (due to having calcerous soil - mine has lots of coral rock sand), it doesn't skew the observed measures for potassium and magnesium, but the reported IDEAL values are higher than they should be. So for my test above, I likely do not need to apply as much K and Mg as is noted in the deficit numbers.

What I've decided to do with RidgeRunner and Daniel's explainations, along with the conversation I had with Bill, is to apply K and Mg this year, either using Epsom salts and SOP or KMAG, whatever is easier for me to get my hands on. My K and Mg is so low, it needs work. Next year, I'll test again and request the ammonium acetate along with a paste test (the paste test uses distilled water). I'll call Logan back, if they can run the ammonium acetate test on the existing sample, I will ask them to do so. Would be nice to have that as a baseline.

I called my local Lesco/John Deere store, which is very close by, and they have KMAG. When I get there later this week, I'll see if they have SOP (and maybe Mg) and compare costs to make my decision on what to apply.

This is fun!

I'll call Logan back, if they can run the ammonium acetate test on the
existing sample, I will ask them to do so. Would be nice to have that as
a baseline.

They can run it on the unused portion that they stored for an additional fee, probably $10-15, and you should get the results by the end of the week.

Would you mind posting them for my curiosity?

FYI Mg can also be skewed (rarely) if the soil contains magnesium carbonate (could occur if there was a recent dolomitic limestone application application or depending on the soil parent material). For some reason I thought you recently moved in. :(

It sounds like you have all you need and are well on your way. Good luck.

PS. One other FYI, the high pH is due to the carbonate which the low 2.4 pH extractant neutralizes, freeing up the calcium (and Mg). This over inflates the the TEC and the BCSR percentages used for balancing the soil. Consequently, as you stated, this inflates the reported Ca, Mg, and K deficiencies.