# Soil test results



## golfingtrigger (Jan 15, 2020)

I got the soil test results back. My question is how many times do I need to apply the triple Superphosphate and lime. Is this a one time deal or do I need to apply multiple times throughout the year?


----------



## Redtwin (Feb 9, 2019)

From what I understand, it takes a long long time to change your soil pH. You'll have to do it little by little and consistently.


----------



## g-man (Jun 15, 2017)

They recommend 50lb/ksqft of lime. You can do 50lb/ksqft every 6 months. So for you, it will be once and done on the lime.

Phosphorus will take a while to get corrected.


----------



## corneliani (Apr 2, 2019)

The problem with smaller yards like yours is that buying a dedicated Phosphorous fertilizer is too much product for your needs, so the 0-45-0 recommendation isn't that feasible (you'd only need 6# for each application, once in the spring and again in the fall). Instead you could consider going with a high P starter fert. If you don't have turf suppliers nearby try Lowes, they carry an 18-24-6 Starter Fert that, when applied at 1#P/1000 (4.16#/1000) would bring you up to the recommended levels. A 50# bag should give you 4 applications, applied monthly starting in spring. Or you have the all-clear to go full Milorganite for the next couple of years if you prefer the organic route.

As for the low pH, if your soils are like ours that 5.5pH seems about normal w/o any amendments. To bump it up to the mid 6's you'll need approx 100# of lime, ideally in 2 separate apps. Again, Lowes sells Dolomitic Pelletized limestone in 40# bags. If you apply 1 bag/1000 in the spring and again in the fall you should be sitting pretty for the next couple years.


----------



## Ridgerunner (May 16, 2017)

Recommended sufficiency range for P (elemental) is between 30 to 60 lbs/acre. The lab is splitting the difference and targeting 45 lbs/acre of elemental P as they are recommending 80 lbs/acre of P2O5 (P2O5 is the form of P that is listed on fertilizer bags). It takes 2.3 lbs of P2O5 to result in the application of 1 lb of elemental P. 
80 lbs/acre of P2O5 = 1.8 lbs of P2O5 per thousand square feet.
That would be 4lbs/M TOTAL of 0-45-0 for the whole year or
7.5 lbs/M TOTAL of the 18-24-6 for the whole year.
If you apply the 18-24-6 at the rate of 4.16 lbs/M, you will meet the lab recommendation for P (plus a pinch to grow on) after only two applications.
But I'm getting old and my reckoning skills may be wanting.

Before applying more than the recommended 50lbs/M of lime, I suggest you check with the lab. I believe when they did the lime calculation they were targeting a final pH of 6.5. Applying more lime can raise your pH above 6.5 and possibly above 7.


----------



## corneliani (Apr 2, 2019)

@Ridgerunner - your reckoning skills are still to be reckoned with, it seems... it is I who miscalculated that simple equation. Thanks for catching that, friend. As for the lime, if one ton of dolomitic will raise soil pH in clay soils by approx 0.5pH, his 1-ph rise would require 2 tons/A... no? Or is my math completely off today.


----------



## Ridgerunner (May 16, 2017)

It's not your math, but the assumption:


> if one ton of dolomitic will raise soil pH in clay soils by approx 0.5pH, his 1-ph rise would require 2 tons/A


Soil pH is a measurement of the amount of hydrogen in solution. Besides the amount of H+ in solution, there is also a "hidden" amount of H+ called reserve acidity or buffered H+/pH. If this reserve pH isn't also neutralized, the solution pH will quickly become acidic again. The amount of reserve H+ is related to the CEC of the soil. Low pH, high CEC soils will usually have more reserve H+/acidity than a low pH, low CEC soil. Therefore, it will take more lime to neutralize the high H+ reserve in a low pH, high CEC soil than is needed to neutralize the smaller H+ reserve in a low CEC soil. Sands are usually low CEC and clays are usually high CEC, so if the solution pH is 5.5 it will take more lime to raise the pH in the clay than the sand soil. However, these are just generalities. These assumptions may or may not be accurate. For instance: although most clay soils have a high CEC (>15) that is not always the case. Clay Soils of the Piedmont region often have a CEC below 7.
Although experience may reflect that adding 1 ton of lime will raise the pH of a clay soil with a CEC of 20-25 by 0.5 of a point, that relationship won't hold true for a Piedmont clay soil with a CEC of 6. 1 ton of lime would raise the pH much more than 0.5 points. In the present case, although I can't tell if the soil is a clay or not, golfingtrigger's CEC is -+ 9ish. 
Having a Buffer pH test (where the lab measures the amount of H+ in solution and reserve) done is the most accurate method currently available for determining the amount of lime needed to achieve a desired pH. Auburn has through buffer pH testing, determined that 1 ton of lime/acre is sufficient to raise the pH to about 6.5 in his 9ish CEC soil..


----------

