[Jeaux Bleaux]

Hey guys, I received my first soil test results. Any help on deciphering what it means, and your guys thoughts on it would be appreciated. Thanks

 

[kur1j]

Looks like you need about ~1lb/1ksqft of P and K. Since you have SA grass I'm not sure what the recommendation is for N but with that soil sample I would be throwing out some 19-19-19 at 1lb/1k with Bermuda.

 

[Ridgerunner]

@Jeaux Bleaux
Welcome to TLF.
LSU uses Mehlich 3 for testing and reports values for each nutrient in parts per million (ppm).
Ideally you will want to have your test reported values to fall within the following M# ranges (realistically, with a fine sand loam, your "target" should be somewhere between the middle and the low end of the ranges):

M3 Ranges (in ppm)

P: 26-54
Ca: 500-750
Mg: 70-140, 60-120 for sands
K: 75-176, 50-116 for sands
Na: unreported/N.A.
S: 15-40
Fe: 50-100
Cu: 0.4-2.5
Zn: 1-2
Mn: 4-8, 8-16 for pH >7
B: unreported/N.A. (update: per PACE and R. Carrow: 0.4/0.5- 1.5)

To calculate what nutrients and how much to add of each nutrient read the Simple Method on pg 4:
https://thelawnforum.com/viewtopic.php?f=22&t=1088&p=58112#p58112
Feel free to post any questions that arise.

Regarding pH, anything between pH 6 and 7 is very good. Your back yard is below this range and you will want to raise it. Per the LSU report (titration w/1T equivalents method), adding one ton of lime should raise your pH to 6.7.
To determine how many pounds of lime per one thousand square feet, divide 2000 by 44 (there is about 43,560 square feet in an acre). That works out to 45lbs of lime per thousand square feet, but a pH of 6.7 is a bit on the high side and the LSU calculation is probably for changing pH to a depth of 6.7 to 8". To be safe (it's easier to raise pH than lower it). I'd suggest you apply only 25 lbs of lime this year and see where your pH settles out on a soil test next year.

 

[Jeaux Bleaux]

Fantastic info! Thank you so much

 

[kur1j]

@Ridgerunner Is the Ph change only temporary? If nothing else is really done will the Ph change drastically over time?

 

[Jeaux Bleaux]

Just be clear, I'm assuming you're telling me to add 25lbs of lime per 1000/sq ft? My backyard is 12,000 sq ft roughly, so I need about 300lbs of lime?

 

[Jeaux Bleaux]

And is there certain times of the year or temperatures when applied, that would be better to do it? Any risk in 90 degree weather like right now?

 

[viva_oldtrafford]

And is there certain times of the year or temperatures when applied, that would be better to do it? Any risk in 90 degree weather like right now?

Yeah 300 lbs is what you need. You can do it anytime you choose to, weather will not have an impact.

 

[Jeaux Bleaux]

Great. Thank you

 

[Ridgerunner]

@Ridgerunner Is the Ph change only temporary?

Yes. How fast and how much of a return to a lower pH will occur will depend on a number of factors such as: climate/rainfall/irrigation/leaching/soil texture, CEC of the soil and type and amount of N fertilizer applied.

If nothing else is really done will the Ph change drastically over time?

Not sure if this is what you are asking, but: With the exception of a peat bog for instance, most undisturbed native mineral soils of the world will have a pH between 4 and 9. This is a result of rainfall/leaching, type of parent material of the soil, and OM decomposition. I would think that if left undisturbed for millennia, these factors would have found an "equilibrium" and pH would remain relatively constant.

 

[Ridgerunner]

Just as an example. I live in Ohio. I have sandy silt soil with a CEC of about 10. Average annual rainfall is 38".
I applied 5-7 lbs of urea/M in most years, plus Milo. In six years my pH has lowered 0.4 from pH 6.5 to 6.1.

 

[kur1j]

@Ridgerunner I've did 2 soil tests last year. One around April/May last year, and then another in late summer (Sept).

The April/May Soil test showed I had pH of 6.42. The one late in the year showed I had a Ph of 5.9. So in a matter of 6 months my Ph. dropped .5 which is the reason I asked how much it can change.

I had a local lawn care company doing my "weed" control (it came with house) and they applied Lime in December. I just sent off another soil sample test today to see where I'm at with things. From my understanding, this clay soil is generally acidic and doesn't hold onto nutrients very well at all. The only positive to it is that it holds moisture really well. Even though I was doing 19-19-19 1lb/1k a month every single test came back low on my P and K. April had a recommendation of .7lbs/1k of P and K (it was a generic recommendation of 3.75lbs of 16-16-16 per 1k). The second soil test I did came back with a recommendation of putting down 1.95lb1/1k P and 1.61lb/1k.

I'm interested to see what this new soil test comes back with. If everything is low...I'm going to up my fertilizer rate. But I digress. I don't want to hijack this post any more than I already did.

 

[Ridgerunner]

@kur1j Ahhh. I was going to mention that but thought it was TMI. Yes, pH can drop up to 1 full point between Spring and Fall due to OM decomposition and N fertilizer application then raise over Winter as H+ is removed from the soil solution during cool temperature rainy months. This is especially pronounced in low CEC or sandy soils in the South. It's one of the reasons why soil testing should always be done in the same month from year to year.

Edited phrasing for accuracy and clarity.

 

[kur1j]

@Ridgerunner I update my post with some more details. I'm going to start a new thread or post in another thread about soil testing to no detract from this person post.

 

[Jeaux Bleaux]

Lol. No worries. I'm learning the more you guys post

 

[viva_oldtrafford]

@Ridgerunner I've did 2 soil tests last year. One around April/May last year, and then another in late summer (Sept).

The April/May Soil test showed I had pH of 6.42. The one late in the year showed I had a Ph of 5.9. So in a matter of 6 months my Ph. dropped .5 which is the reason I asked how much it can change.

I had a local lawn care company doing my "weed" control (it came with house) and they applied Lime in December. I just sent off another soil sample test today to see where I'm at with things. From my understanding, this clay soil is generally acidic and doesn't hold onto nutrients very well at all. The only positive to it is that it holds moisture really well. Even though I was doing 19-19-19 1lb/1k a month every single test came back low on my P and K. April had a recommendation of .7lbs/1k of P and K (it was a generic recommendation of 3.75lbs of 16-16-16 per 1k). The second soil test I did came back with a recommendation of putting down 1.95lb1/1k P and 1.61lb/1k.

I'm interested to see what this new soil test comes back with. If everything is low...I'm going to up my fertilizer rate. But I digress. I don't want to hijack this post any more than I already did.

Clay is great at holding nutrients...for the same reason it is great at holding water, it is negativley charged - water is polar and the cations are + charged, so they stick to clay very easily.

@ridgerunner would OM decomposition really factor into pH adjustments so quickly, especially in a turfgrass envrionment? Sure, OM decomposes, but as long as there's healthy sward, OM is accumulating at an even faster rate (why we see %om in soil tests always increase and not decrease). 1 full point is a ton...using an acidifying fert? Sure. OM degradation leading to a point drop (logarithmic measurements here) seems a little much.

 

[kur1j]

@viva_oldtrafford Interesting. Someome at a local nursery told me the exact opposite. They sent off a soil test for me and when it got back they were explaining why all the nutrients were really low. The tests were showing that I was low 1-2lbs for both P and K. It was showing everything being low except calcium and surfer. I've got a soil test on headed to a lab now so I'll see if anything has changed. But if everything is still really low, would I just need to dump a lot more fertilizer and some micronutrients?

 

[g-man]

@kur1j Do you have a copy of those test results (from local nursery)? If you do post them in a new thread and then add report from waypoint when you get it.

 

[viva_oldtrafford]

@viva_oldtrafford Interesting. Someome at a local nursery told me the exact opposite. They sent off a soil test for me and when it got back they were explaining why all the nutrients were really low. The tests were showing that I was low 1-2lbs for both P and K. It was showing everything being low except calcium and surfer. I've got a soil test on headed to a lab now so I'll see if anything has changed. But if everything is still really low, would I just need to dump a lot more fertilizer and some micronutrients?

This person lied to you.

 

[kur1j]

@g-man

I posted them here. I'll add the waypoint test as soon as I get it.
https://thelawnforum.com/viewtopic.php?f=24&t=3447

@viva_oldtrafford Thats been the story of my life when dealing with anyone locally unfortunately. At the time I knew enough about the soil test to know what the recommendation ma meant. I asked them if I should apply the recommended amount all at once and they were like just continue doing the 1lb monthly "since this soil doesn't hold nutrients well you will always get low nutrients scores like this".

I certainly believe your knowledge over them. But unfortunately that is the assumption I was working under and just took it as fact. I'm glad I made the comment and you cleared that up for me. This gives me completely different outlook on my soul samples and raises more questions.