timtsb

Logan Labs Soil Analysis

timtsb
last month

Posting for a friend. Morpheus - hoping you’re still on here analyzing these?

Comments (6)

  • morpheuspa (6B/7A, E. PA)
    last month

    No. No I'm not. :-)


    Your friend has really nice soil, actually. I'd guess kind of sandy, kind of silty, off the cuff. Clay seems unlikely, but he or she (he from here on out to avoid double-typing) could have Bentonite or one of the lightest, lowest-EC clays. The soil won't hold vast resources at any one time, but won't be bouncing all over the place, either.


    pH 6.7 average: Perhaps a bit high, but who cares? It's close enough. The technical top range is around 6.8, I like to see a "perfect" balance a little lower than that if it can be managed. pH really makes no never-mind but people seem to care about it, so I mention it.


    OM: 4.2 and 5.1: Excellent. There's no reason to not mulch mow, mow in fall leaves, feed organically, and so on, but there's also no reason to make a special effort to increase OM.


    Sulfur 7, 8: Works for me. It's textbook a bit low, but that's not a problem. We'll be pushing this up a little bit anyway.


    Phosphorus 600-ish: Very high. No P is or will be needed for the foreseeable future. We're talking many years to decades, for the average lawn. If he's using starter fertilizer or anything with phosphorus (the second number) in it, stop. It's not doing harm, but there's certainly no need to spend the money. Most vegetable gardens also won't require any more. Flower gardens will be OK with this, but some will need more (mine are balanced around 1,000 for a long list of reasons and other things the P is balanced against that are high).


    Calcium 71%, 74%: Textbook a little high and setting off the pH I noted above. It's no big deal and having a little extra calcium in this range is not a problem. It's not particularly competitive in this tiny an excess, won't cause issues, and I'd rather see a little more than a little less--particularly when compared against the magnesium.


    Magnesium 15%, 15%: At the high end. Excess Mg will tighten a soil and make it problematic to dig. This might be happening here, it's a borderline case, but there's enough calcium to be offsetting that tendency...barely. I don't want to and really can't fiddle with these specifically, so we live with what we have. I can't jettison the magnesium and don't want to add any more calcium.


    Potassium 2.3, 2.1: On the low end. K is the least of the three that influence the pH on this scale (there are really four, but the fourth is toxic and next down...we'll get there). I'd actually like to see more. I've made recommendations below, and we're going to use potassium sulfate to fix this. If your friend can't source that, I can make other recommendations, but I have a strong preference for potassium sulfate. Most landscape places and garden stores will order it for you in larger quantities, but don't often have big bags in stock.


    Sodium Around 1%: This is a little high-ish, but not of great concern. If he uses softened water on the lawn, or is near the ocean, or is just off a heavily-salted roadway (in winter), that explains it. I wouldn't want to see it go too terribly much higher, but if it does, it can be fixed. In this range, it should have little to no impact on anything.


    Minor Elements:

    Boron is a tad low (target being 0.7 PPM), but not enough for me to bother tapping it. Trying to adjust 200 parts per billion can be a bit of a trial and I'd rather not overshoot with somebody whose experience level I don't know. It's not important anyway, grasses aren't going to have a problem with 0.52, and 0.68 is perfect.

    Everything else is within optimal range, amazingly, including iron. There's certainly no bar to adding more iron if your friend wants to, in the form of iron sulfate, or Milorganite, or Bay State, or anything else they want. Iron's not toxic until 50,000 PPM or more and a low pH.


    Retest: With this EC, retests can be every 2 years for the hobbyist, every 3 years for the concerned, and when stuff looks bad for the merely curious. :-)


    Recommendations:


    We have time to squeeze an app yet this year if things can be purchased quickly. If not, just ride an app into next year. This soil is good enough that there's absolutely no rush and grass/gardens shouldn't be showing any problems arising from any "shortage" in the soil. These amount to adjustments.


    October 20th, 2020: Apply 2 pounds of potassium sulfate per thousand square feet.


    May 1, 2021: Apply 2 pounds of potassium sulfate per thousand square feet.


    June 1: Apply 2 pounds of potassium sulfate per thousand square feet. Feed the lawn normally around this time.


    September 1: If you skipped the October 20th, 2020 app, apply 2 pounds of potassium sulfate per thousand square feet. Regardless of that, feed the lawn normally around this time.



  • timtsb
    Original Author
    last month

    Wow, that was fast! I’m happy to see his Ph is good...he installed sod last year and put down a lot of lime without a soil test but I guess it worked out nicely. Funny his test is similar to what mine was last year with the same corrective measures. We live close to each other so I guess that makes sense.

    Phosphorus - not sure what he used previously but I recently switched him over to Oceangro (milorganite).

    Sodium - we live a few miles from the ocean but just down the street from a back bay. He has a well but I’m on city water. Would the well in close proximity to tidal waters explain the high sodium?

    Thank you as always for your time and assistance!

  • morpheuspa (6B/7A, E. PA)
    last month

    You got lucky, normally I'm busier than a one-armed paper hanger on Thursdays. Tonight is an exception.

    If he dropped lime blindly, he somehow hit optimal levels very, very closely without trying. That is almost miraculous...

    OceanGro is fine. It's kind of high in terms of phosphorus, but it won't build that fast. And with the slightly-on-the-high-end pH, the P is more bound than it would be otherwise (and P is well-bound at any pH, really). I'm OK with it. If things start to kilter out of control, we simply raise the P antagonists to counter the fact that they won't be well-absorbed. At this point, this is not an issue.

    Really, people make much ado about nothing in terms of P fighting other resources, it's not a big deal at these kinds of levels (you really have to bork a soil for it to be a problem). I'd be more concerned about potential erosion of soil from the property into waterways or the bay, in his case. High-P soils in waterways cause major algal blooms and are a major pollutant.


    I'm not a well-water expert, but I'd think 1% sodium would make the water kind of brackish and distasteful? Although it could simply be that repeated shallow(ish) watering is causing a sodium buildup in the soil, in which case the water would simply be a little sodic, and the resulting watering just leaving behind sodium with each watering.

    During years of decent precip, which this sure wasn't, that should tend to wash out, with sodium amounts dropping in winter, spring and fall.

    It's not so high that I'm worried all that much and we can file it under "Keep An Eye On, Things To" for now. Grass won't panic over 1% sodium at that soil exchange capacity, although it's likely to wilt more easily when getting close to the dry end of the spectrum just due to increased osmotic pressure from the salt.

  • timtsb
    Original Author
    last month

    I should clarify his house is on city water and the well is only for lawn. It leaves his (and all other neighbors who have one) sidewalks, tree trunks, and everything else the sprinklers hit brown with what I assume is rust, but maybe it’s related to sodium? Or both. We’re about 1/10 mile from the water, and the wells have to be surprisingly deep here...over 100 feet I believe

  • timtsb
    Original Author
    last month

    I just went back and revisited my soil sample from last year (skipped it this year) and my sodium is actually a hair higher than his, so I guess unrelated to well vs city water

  • morpheuspa (6B/7A, E. PA)
    last month

    Probably it's localized then. I don't have much experience with areas very close to ocean/bay water, but a quick trip through Memory Lane (research) indicates that salt spray is not exactly rare even several miles away. Sodic sources are, actually, planetary (I knew that one, which is why desert soils are sodic as well), but it's much more common even some distance from the ocean.


    It's just also more often washed out by the more-than-sufficient rainfall in those locales. Except where the soils are rather sandy (as the EC here indicates) and the amounts aren't large, but show in the EC. Which, as I look above, is the case. Fifty pounds per acre isn't all that much, really.


    So no worries.