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Tifgrand—7,500 sq/ft—Baroness LM56
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Hello all!! I have put together a VERY BASIC tutorial on what numbers you want on your soil test from Logan Labs. This is by no means a way to read your own test as there are a lot of variables that go into everything, but at least you will have an idea of how far off your soil really is. I will go into greater detail down below.



Sample Depth: You want to take the soil sample just from the 1" of soil between the 3-4" depth. As this is where most of the roots are for the grass.

Total Exchange Capacity (TEC): This number basically states how much nutrients you soil can hold. A low number basically means you have a Sandy soil (Anything below 7) and as the numbers rise you will get into better soil holding capacity. A TEC of 12 is optimal but if you have any kind of crazy high number or live around TX, you may need an AA(Ammonium Acetate) test as you will usually have a high content of Calcium which throws the numbers off.

pH of Soil Sample: This lets you know the pH of your soil. Depending on what type of grass you are trying to grow, you will want to have an optimal pH of 6.5-6.8. Now, if you Centipede, you will want that number down in the 5's as it prefers an acidic soil and bermuda will do just fine at about any pH. The closer you are to the optimal pH though, the more nutrients will be available to the grass except Iron, it becomes less available as the pH goes up.

Organic Matter Percent: The more OM you have the better your soil will hold nutrients. 4% is a good base to have but 6-10% is optimal. One caveat to this is that if you are mowing with a reel mower and mowing under .50" it may become an issue as the soil will be soft and your mower will sink into the turf more which may cause some scalping. If you are mowing high (above 1") it shouldn't really become an issue.

Mehlick III Phosphorus: You want this number around 200-250 with an optimal pH but if it's a little off there really isn't a lot to worry about here as Phosphorus doesn't move in the soil really fast regardless of your TEC.

Calcium: This is one of the nutrients at can raise your pH and the test alone will let you know whether you are deficient or not. You do want to have a Ca:Mg ratio of 7-10:1. This is where a good Calcitic Lime(fast acting) is usually recommended depending on your pH and/or Ca:Mg.

Magnesium: As stated above, this is the other nutrient in your Ca:Mg ratio and you would want to add Epsom Salt to the lawn if this number is low or the ratios are out of balance.

Potassium: This too will tell you if you are deficient or not and Potassium(K) does leach from the soil but not as fast as Nitrogen does but it is still not a bad idea to buy some fertilizer with a little bit in it just to keep the numbers from falling depending on your TEC number. This helps harden the grass and also helps to fight of diseases.

Calcium %: You obviously want this number in the range given on the test and it should correlate to the 7-10:1 ratio of the Magnesium %

Magnesium %: In the Range given and within the 7-10:1 ratio with Calcium

Potassium %: In the Range given

Boron (ppm): You want this number in the 1-2 ppm range. Borax is what you would want to add to bring this number up but a bit of WARNING putting too much Boron(Borax) can do extensive damage to your lawn, so you REALLY want to tread lightly here if you are wanting to tackle this deficiency.

Iron(ppm): You want this number as high as possible since it is what gives your lawn that nice dark green color. A number of 400 ppm is optimal. You can spray a foliar app of Iron(Fe) every 2-3 weeks to keep your lawn a dark green but you may also want to watch the temperature as it "can" burn some grasses at higher temps.

Manganese(ppm): You want this between 10-20 ppm

Copper(ppm): You want this between 1-2 ppm

Zinc(ppm): You want this between 5-10 ppm

Anything in the test I did not cover is because I don't have any info on those subjects at this time. This if for INFORMATION purposes ONLY. I just wanted to put this info out there so if you do get a soil test done YOU can understand it better and maybe know more of what is going on with your soil. I don't believe you NEED a soil test done unless you are just curious to see where your soil is at or you have some issues that just can't be explained or fixed but most grasses will do just fine in "less than optimal" soil. Also note that when you start adding things to the soil it can throw other numbers off so please take that into account if you choose to go it alone. Please let me know what you think and I would be happy to discuss any questions you might have.
 

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I have a few quibbles and other considerations regarding Mighty Quinn's explanation of the Logan test. First, a quibble. Most labs instruct you to take a sample from 0 down to whatever level you're testing. For turfgrass 0-4 inches is a good depth to test. Using only the inch between 3-4 means you are deliberately blinding yourself to 0-3 inches. There's a lot going on there, as phosphorus and lime move slowly and past amendments may well be in 0-3. You have better information if you use 0-4. Soil test calibrations assume the soil is sampled from the top to the bottom. That said, if you have been using the inch 3-4 in past years, you will have a better comparison to past years' tests if you keep using the same depth as you did in the past.

The TEC number, like Mighty Quinn said, shows how well your soil holds nutrients. I will add that there is nothing much you can do about it. It is useful information, though, especially if your TEC is low. If your soil doesn't hold nutrients well, you should do more frequent applications at lower rates.

Mighty Quinn's target for P2O5 (200-250 lb/ac) works out to 66-83 ppm of P when 4" soil depth is reported. That is above the Sufficiency Level of Available Nutrients (SLAN) target for a Mehlich 3 tested soil, which is 50. Alkaline soils tend to be low on phosphorus because it gets bound up quickly with calcium and is then unavailable so going a bit above 50 may be good for alkaline soil. However, mycorrhizae are inhibited in high phosphorus soils and they are so beneficial, it's worthwhile to keep phosphorus levels from getting too high. 50 ppm of P is 114 ppm of P2O5. 114 ppm of P2O5 is 114 lb/ac at 3", 152 lb/ac at 4", 190 lb/ac at 5", 228 lb/ac at 6".

SLAN recommends 15-40 ppm sulfur. Sulfur, like nitrogen, will vary a lot week to week.

The Logan deficits for calcium, magnesium, and potassium are for lb/ac for whatever depth you reported. You can't use the standard "ppm x 2 = lb/ac" formula. If you report 4 inches, that is your deficit for 4 inches. To apply an amendment to meet the deficit over a 6 inch depth, you must multiply by 1.5. Furthermore, you must then find the amount of CaCO3 or K20 or MgCO3 or whatever to supply the deficit of that element. Then you must find the amount of CaCO3 or K2O or MgCO3 or whatever in whatever product you're using. Then you must convert lb/ac to lb/k.

There is another way to calculate Ca, Mg, and K deficits. The SLAN recommendations for soils (other than sands) tested with Mehlich 3 are:
Calcium > 750 ppm
Magnesium > 140 ppm
Potassium > 110 ppm
To use this method, you have to convert the Logan lb/ac numbers to ppm. If you report 4 inches, multiply by 0.75. if you report 6 inches, multiply by 0.5. if you report 3 inches, ppm is the same as lb/ac. Then, as with phosphorus, subtract your ppm number from the target. Then to get lb/ac for doing an application to amend 6 inches, multiply by two. You then have to find the amount of CaCO3 or whatever to supply that amount of Ca or whatever and the amount of product to supply that amount of CaCO3 or whatever. Then convert lb/ac to lb/k.

If all these calculations are worrisome, then why not use a lab that sends recommendations back along with the test? They will tell you if you need lime and how much you need. They will tell you the lb/k of P2O5 and K20. Then you just have to figure out the products to supply it. If you need lime and magnesium is low, dolomitic lime will supply calcium and magnesium. If magnesium is sufficient, use calcitic lime.

Fast acting calcitic lime does bring up a pH quickly (weeks instead of months). However, it is short lived. If the lime requirement is 100 lb/k, you really do need all 100 lb/k. Using fast acting lime does not mean you can get away with using less. It does mean you can only do a little bit at a time. Application rates for the fast acting lime are limited to around 9 lb/k. With ordinary lime, you can use up to 50 lb/k per application. It is slower but it sticks around for years. I would suggest combining them, using some fast acting lime and some slow lime. When at another site you may have been given a recommendation for 2-3 applications of fast acting lime, it was only to raise the pH for that year only. It was not fulfilling calcium deficits. Those were not normally calculated.

Epsom salt does not raise pH. If your pH is low and you need magnesium, dolomitic lime will raise pH and supply magnesium. If your pH is high and you need magnesium, Epsom salt will supply magnesium without raising pH. Gypsum does not raise pH. If your pH is low and you need calcium, calcitic lime will raise pH and supply calcium. If your pH is high and you need calcium, gypsum will supply calcium without raising pH. Potassium sulfate and potassium chloride do not raise pH. It is the carbonate action of lime that raises pH.

A good calcium to magnesium ratio helps with soil flocculation. The ratio can vary, though. For a sandy soil, 3:1 would tighten up the soil. Logan's "ideal" of 68% Ca to 12% Mg is 5.7:1. For a clay soil, a higher amount of calcium to magnesium might be better. In general, if you make amendments to meet soil test recommendations, you will have an acceptable ratio. Note that the SLAN targets of 750 ppm Ca and 140 ppm Mg are a 5.4:1 ratio. I have never seen a 10:1 ratio recommended.

Micronutrients are rarely needed for turfgrass. However, in alkaline soil, iron, manganese, copper, and zinc are less available. Molybdenum is less available in acidic soil. Boron is less available in moderately alkaline soil. Robert Carrow in Turfgrass Soil Chemical Problems and Fertility gave these sufficiency ppm numbers for micronutrients tested with Mehlich 3:
Fe > 100
Mn > 6.0 (pH 6.0)
Mn > 12 (pH 7.0)
Zn > 2.0
Cu > 2.5
He did not give a number for boron or molybdenum. Boron toxicity is more of a problem than deficiency. This article gives information and suggests tissue testing if you are concerned about boron:
https://www.google.com/url?sa=t&source=web&rct=j&url=http://archive.lib.msu.edu/tic/golfd/article/2002marT11.pdf&ved=0ahUKEwiLmNuE8eXUAhVGcT4KHfldBx8QFggdMAA&usg=AFQjCNEoIcpe7N7RQij1jeD5DD1NgFAiUw
Note that the ppm discussed there is ppm of the tissue, not of the soil. Many fertilizers say they "contain micronutrients" and that is one way to get some.

Logan does not send recommendations or do a buffer pH test without additional charge. There are many private labs and state college labs that include both recommendations and the buffer test for about the same cost or even less. And you won't have to puzzle through all the math just to know what your deficits are. All you will have to do is figure out which products will supply the deficits and when to apply them and how much at a time. There are plenty of people who can help with that.
 

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Tifgrand—7,500 sq/ft—Baroness LM56
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Discussion Starter · #6 ·
Virginiagal said:
I have a few quibbles and other considerations regarding Mighty Quinn's explanation of the Logan test. First, a quibble. Most labs instruct you to take a sample from 0 down to whatever level you're testing. For turfgrass 0-4 inches is a good depth to test. Using only the inch between 3-4 means you are deliberately blinding yourself to 0-3 inches. There's a lot going on there, as phosphorus and lime move slowly and past amendments may well be in 0-3. You have better information if you use 0-4. Soil test calibrations assume the soil is sampled from the top to the bottom. That said, if you have been using the inch 3-4 in past years, you will have a better comparison to past years' tests if you keep using the same depth as you did in the past.

The TEC number, like Mighty Quinn said, shows how well your soil holds nutrients. I will add that there is nothing much you can do about it. It is useful information, though, especially if your TEC is low. If your soil doesn't hold nutrients well, you should do more frequent applications at lower rates.

Mighty Quinn's target for P2O5 (200-250) works out to 88-110 ppm of P. That is well above the Sufficiency Level of Available Nutrients (SLAN) target for a Mehlich 3 tested soil, which is 50. Alkaline soils tend to be low on phosphorus because it gets bound up quickly with calcium and is then unavailable so going a bit above 50 may be good for alkaline soil. However, mycorrhizae are inhibited in high phosphorus soils and they are so beneficial, it's worthwhile to keep phosphorus levels from getting too high. 50 ppm of P is 114 ppm of P2O5. If you want to know your deficit, subtract your number from the target. To get lb/ac, multiply ppm by 2. To get lb/k, divide the lb/ac number by 43.56. If your number is above 114 ppm of P2O5, you have sufficient phosphorus.

SLAN recommends 15-40 ppm sulfur. Sulfur, like nitrogen, will vary a lot week to week.

The Logan deficits for calcium, magnesium, and potassium are for lb/ac for whatever depth you reported. You can't use the standard "ppm x 2 = lb/ac" formula. If you report 4 inches, that is your deficit for 4 inches. To apply an amendment to meet the deficit over a 6 inch depth, you must multiply by 1.5. Furthermore, you must then find the amount of CaCO3 or K20 or MgCO3 or whatever to supply the deficit of that element. Then you must find the amount of CaCO3 or K2O or MgCO3 or whatever in whatever product you're using. Then you must convert lb/ac to lb/k.

There is another way to calculate Ca, Mg, and K deficits. The SLAN recommendations for soils (other than sands) tested with Mehlich 3 are:
Calcium > 750 ppm
Magnesium > 140 ppm
Potassium > 110 ppm
To use this method, you have to convert the Logan lb/ac numbers to ppm. If you report 4 inches, multiply by 0.75. if you report 6 inches, multiply by 0.5. if you report 3 inches, ppm is the same as lb/ac. Then, as with phosphorus, subtract your ppm number from the target. Then to get lb/ac for doing an application to amend 6 inches, multiply by two. You then have to find the amount of CaCO3 or whatever to supply that amount of Ca or whatever and the amount of product to supply that amount of CaCO3 or whatever. Then convert lb/ac to lb/k.

If all these calculations are worrisome, then why not use a lab that sends recommendations back along with the test? They will tell you if you need lime and how much you need. They will tell you the lb/k of P2O5 and K20. Then you just have to figure out the products to supply it. If you need lime and magnesium is low, dolomitic lime will supply calcium and magnesium. If magnesium is sufficient, use calcitic lime.

Fast acting calcitic lime does bring up a pH quickly (weeks instead of months). However, it is short lived. If the lime requirement is 100 lb/k, you really do need all 100 lb/k. Using fast acting lime does not mean you can get away with using less. It does mean you can only do a little bit at a time. Application rates for the fast acting lime are limited to around 9 lb/k. With ordinary lime, you can use up to 50 lb/k per application. It is slower but it sticks around for years. I would suggest combining them, using some fast acting lime and some slow lime. When at another site you may have been given a recommendation for 2-3 applications of fast acting lime, it was only to raise the pH for that year only. It was not fulfilling calcium deficits. Those were not normally calculated.

Epsom salt does not raise pH. If your pH is low and you need magnesium, dolomitic lime will raise pH and supply magnesium. If your pH is high and you need magnesium, Epsom salt will supply magnesium without raising pH. Gypsum does not raise pH. If your pH is low and you need calcium, calcitic lime will raise pH and supply calcium. If your pH is high and you need calcium, gypsum will supply calcium without raising pH. Potassium sulfate and potassium chloride do not raise pH. It is the carbonate action of lime that raises pH.

A good calcium to magnesium ratio helps with soil flocculation. The ratio can vary, though. For a sandy soil, 3:1 would tighten up the soil. Logan's "ideal" of 68% Ca to 12% Mg is 5.7:1. For a clay soil, a higher amount of calcium to magnesium might be better. In general, if you make amendments to meet soil test recommendations, you will have an acceptable ratio. Note that the SLAN targets of 750 ppm Ca and 140 ppm Mg are a 5.4:1 ratio. I have never seen a 10:1 ratio recommended.

Micronutrients are rarely needed for turfgrass. However, in alkaline soil, iron, manganese, copper, and zinc are less available. Molybdenum is less available in acidic soil. Boron is less available in moderately alkaline soil. Robert Carrow in Turfgrass Soil Chemical Problems and Fertility gave these sufficiency ppm numbers for micronutrients tested with Mehlich 3:
Fe > 100
Mn > 6.0 (pH 6.0)
Mn > 12 (pH 7.0)
Zn > 2.0
Cu > 2.5
He did not give a number for boron or molybdenum. Boron toxicity is more of a problem than deficiency. This article gives information and suggests tissue testing if you are concerned about boron:
https://www.google.com/url?sa=t&source=web&rct=j&url=http://archive.lib.msu.edu/tic/golfd/article/2002marT11.pdf&ved=0ahUKEwiLmNuE8eXUAhVGcT4KHfldBx8QFggdMAA&usg=AFQjCNEoIcpe7N7RQij1jeD5DD1NgFAiUw
Note that the ppm discussed there is ppm of the tissue, not of the soil. Many fertilizers say they "contain micronutrients" and that is one way to get some.

Logan does not send recommendations or do a buffer pH test without additional charge. There are many private labs and state college labs that include both recommendations and the buffer test for about the same cost or even less. And you won't have to puzzle through all the math just to know what your deficits are. All you will have to do is figure out which products will supply the deficits and when to apply them and how much at a time. There are plenty of people who can help with that.
Great addition Virginiagal!! I only posted the above info for a general rule of thumb so people could get a basic idea of what to look for and it had been over a year since I had done any soil test reading so I was a little rusty to say the least :D . You've really been doing your homework on the subject and it shows :thumbup: Thank you for filling in a lot of the blanks.
 

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One thing I may not have made clear: the best way to know how much lime is needed is to have a buffer pH test, which is a pretty normal thing in soil tests. You have to pay extra at Logan to get one. The lab uses that result to make a lime recommendation to bring your pH up to a target, most likely 6.5. And if you use the SLAN approach, use the "values reported," not the deficit.
 

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Gosh! I'm glad I stumbled here!

I bought a 3/4" soil sample tube and it's taking FOREVER to get two cups of soil between the 3-4" level. If I read this right, just grab the whole core and have it tested?

Also, Logan Labs has been the Holy Grail. I live in Massachusetts and understand UMass' tests are pretty good. Has anybody used them? Have you called them for recommendations and that sort of thing?

As an aside... I've always thought that the guys and gals at the extension would be enthusiasts like me and only too happy to spend time discussing tests.
 

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There is a soil test being promoted (on youtube, The Grass Nut?) and marketed as Soil Savvy. As Soil Savvy/Unibest is not particularly forthcoming on their site with any details regarding the chemistry, lab procedures or results of any studies performed, it is impossible to make any assessment of the accuracy and validity of this product and none is intended in making this post. However, the point of caution: Even if this is an accurate and valid test for determining soil nutrients, Soil Savvy (when contacted) has stated that the recommendations are for one application only and that a new test should be performed prior to making each of any future applications. That would require performing at a minimum, two tests, and possibly many more before nutrients reach desired levels.
 

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dfw_pilot said:
That's probably debatable. $25 without shipping with no interpretation marks it off my list of "Grail" candidates. UMass or your local extension is probably just fine.
Yep! It's county extension for me. They know the soil around here in Massachusetts, do the required tests for my area, and provide recommendations.

The only reason why I would have gone Logan would have been to get some help from people who have experience with a test. Logan is known around the country and I figured I could find help if I needed it.

My county guys and the good folks at The Lawn Forum are all I will need. Thank you so very much!
 

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I'm going to keep using Logan because that's what I started with. I've got 4 years of tests and now I can see the changes between each year it's kinda interesting. I did think it was odd that I needed a secretive team to interpret it for me, but as I learn more about what all the numbers mean I realize that is not the case. I also like that it's a nice PDF format =P
 

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GrassDaddy said:
I'm going to keep using Logan because that's what I started with. I've got 4 years of tests and now I can see the changes between each year it's kinda interesting. I did think it was odd that I needed a secretive team to interpret it for me...
I'm hip! I figure I can handle the numbers, too. I'll probably be looking for source material to make adjustments. Like, if something "nerdy" like zinc is low, how to move the dial on it.

From what I've read, it's mostly NPK, pH, calcium and magnesium that I should zero in on. I'm glad I learned about the different kinds of lime. I will need help on that one.

My eye-opener for lawn care was the difference gypsum made to the edges of my lawn near the salty sidewalk. Wow! Talk about an "a-hah!" moment! Once I saw crabgrass coming up there, I knew it wasn't long before I could get real grass to grow there! :lol:
 

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BXMurphy said:
Gosh! I'm glad I stumbled here!

I bought a 3/4" soil sample tube and it's taking FOREVER to get two cups of soil between the 3-4" level. If I read this right, just grab the whole core and have it tested?

Also, Logan Labs has been the Holy Grail. I live in Massachusetts and understand UMass' tests are pretty good. Has anybody used them? Have you called them for recommendations and that sort of thing?

As an aside... I've always thought that the guys and gals at the extension would be enthusiasts like me and only too happy to spend time discussing tests.
FWIW, in July I used the same soil sample to send to Logan Labs and Umass for testing. There was definitely some variation between the two and the Umass test did come with some very rudimentary recommendations. I did ask Umass a few questions via email (to [email protected]) and they were answered within a couple of days, although not what I would call at the "enthusiast" level. I was considering starting a thread and showing both reports and comparing the "lawn nut" approach I've seen with similar Logan Labs reports online to the Umass "ho hum" recommendations, but I've been doing things like spending the better part of my afternoon dethatching my front yard. :D

FWIW, the lab reports are cheap enough where I'll probably send soil samples to both labs next spring too.
 

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Indexed common fertilizer acidifying effects:

Sulfur coated Urea (38-0-0): 1.18
Ammonium Sulfate (21-0-0): 1.10
Urea (46-0-0): 0.81
Ammonium Nitrate (34-0-0): 0.60

Higher numbers indicate greater acidifying effect. For reference, the index of Elemental Sulfur is: 3.12. One pound of sulfur will neutralize 3.12# of 100 CCE limestone; therefor, 1# of Ammonium Sulfate (21-0-0) will neutralize 1.10 pounds of 100 CCE limestone and 5# of 21-0-0 (equal to an application of 1.05 lbs/k of N) would neutralize 5.5 lbs of 100 CCE of limestone. Theoretically, of course. :)
 

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BXMurphy said:
FWIW, in July I used the same soil sample to send to Logan Labs and Umass for testing.
Thank you for jumping in, massgrass.

I think there will always be variations. It's just like the guy with two watches... he never knows what time it is. The guy with one watch? He always knows the time!

I figure I am Leap Years ahead of the neighbors with a soil test and "close enough" apps of the proper enhancers at the right time but... I would LOVE to see a thread on two soil samples. Do you think they would be so far off as to make a serious impact?

BTW... next year I'm driving to Quincy for Bay State Fertilizer. It's an hour and a half but at about $3.50 for 40 pounds... yeah, I'll drive.

Thank you again.
 

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Ridgerunner said:
Indexed common fertilizer acidifying effects:
Very interesting chemical analysis. I will be starting the fall nitrogen blitz for the first time with some urea. I'm waiting on soil tests but anticipate acidic soil. Nice to know that urea has a lower affect on acidity.

I am so glad to be free of the hardware store bags of whatever is on sale. I am happy to know what I am actually doing for a change! :)
 
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