Aeration wouldn't really help..

from what I can look up on high Ca in soil It dose not seem to effect anything have you taken a soil/water Ph test?

Toxicity

Calcium, for all practical purposes, is not
considered to have a directly toxic effect on plants. Most of the
problems caused by excess soil Ca are the result of secondary effects of
high soil pH. Another problem from excess Ca may be the reduced uptake
of other cation nutrients. Before toxic levels are approached in the
plant, crops will often suffer deficiencies of other nutrients, such as
phosphorus, potassium, magnesium, boron, copper, iron, or zinc. http://www.spectrumanalytic.com/support/library/ff/Ca_Basics.htm

Not very likely.

Are you working from a soil test? If so, could you post it? Where are you getting the preferred values?

Btw, Gypsum can reduce Mg held by cation sites, but it does so by raising Ca.

Yes, this is the soil test:

http://st.hzcdn.com/simgs/19b298fa069f977e_8-9591/home-design.jpg

My understanding is that my area is known for "tight" clay soils and magnesium is the culprit.

I thought raising Ca would help with the soil's tightness. It seems that it be hard to add so much gypsum that it would be a problem, but I wasn't sure if it would help with the soil's tightness.

Aeration was recommended as a temporary fix for the soil's tightness. But of course it won't reduce Mg per se.

I was confused by your statement that Ca was 2x and Mg 2 1/2 times preferred levels.

Gypsum can knock off some Mg and reduce the Mg affect of binding clay particles to one another. I've found it to be a rather slow process. Applying gypsum post aeration can aid in incorporating it into a deeper profile of the soil, keep in mind that aeration effects less than 10% of the soil per time. I'm surprised that the level of OM hasn't resulted in more acceptable tilthe for you. It's a little unusual to see those Mg/Ca ratios, you in Wisconsin or Minnesota?

This test is wildly inconsistent and I wouldn't even say it's worth the paper it's printed on.

Consider--your pH is listed at 6.7, which is within the optimal range, with a high CEC of 14 (the soil's ability to hold resources). There's no actual PPM or PPA listed for calcium, magnesium, or potassium, just an index value. Excessive Ca and Mg won't produce a pH of 6.7, it should be 7.5 or higher unless balanced by sufficient acidic anions. Yours isn't.

So something's awry there, and that's not even mentioning the whacky results in the minor elements.

Calcium doesn't make a soil tight--quite the opposite. Magnesium does, but if balanced by sufficient calcium, it tends to be countered well enough, so no problems there. Neither Ca nor Mg are toxic to grasses under most circumstances, but may cause chlorosis due to the fact that the high pH limits iron uptake. Other shortages can also result, but again, that's uncommon. People grow great lawns in limestone chips.

I'd have this soil retested through Logan Labs.

Thanks to all, especially morpheuspa, for your counsel. I have a enough of a philosophy of science background to get that real rigor is pretty difficult to achieve, but don't know enough about soil chemistry to find the B.S.

I'll follow up with a Logan Labs test and hopefully I'll then be in a better spot to understand.

The choice to go to Logan Labs was made several years ago. LL was picked after UMASS fell behind in the rankings. Those two labs achieved high marks in accuracy and repeatibility over several years. Soils were sent to all the top recommended labs several times. LL and UMASS hover way above the heap of soil test labs. All the rest are fall into the heap with most university tests forming the actual base of the heap. The lab at Texas A&M had to send out an apology and recant for 10 years of soil tests they later found out were significantly inaccurate.

I missed the index label and assumed ppm, my bad :( In my defense that is a hard image to read for me.

I'm guessing you're in Md. now? :)

Indexes convert ppm/lbs per acre to a scaled number where a score of 100 is considered sufficient for plant needs. Ever more often, the BSCR school of soil nutrient balancing is falling out of favor and being replaced with nutrient sufficiency levels. Commonly, these indexes are being employed to comply with environmental legislation. You will want to see if you have local/state P restrictions.

Depending on the testing procedures used, nutrient value results can vary significantly. The tests employed are not given and would impact a reading as specific recommendations are given based on known test values and that cannot be done accurately without conversion. However, that doesn't preclude some generally useful observations

Converting your index numbers to lbs/ac results in a Ca;Mg ratio of 5.5:1. Although a bit low for the BSCR school (and a Mg ppm over 300-yours is 330- is predicted to have some detrimental effect to soil tilthe), the ppm values are well above nutrient sufficiency levels and not a nutritional problem, nor do they present any other problem. That they are above sufficiency levels is why they are indexed as excessive. In the case of Mg, K and Ca that is not a warning of danger, just a label.

All in all, your soil is near perfect and should produce a great lawn with standard management practices.

Quite apart from that, my point is actually that there's absolutely no way reasonable sulfur levels and indices over 200 on calcium and magnesium are producing a pH of 6.7. Something's wrong, and it's not clear what the error is.

Maybe, but most likely not. Baring any sampling error, the LL test should coincide with this test producing a CEC in the mid teens, a Ca reading of about 3700 lbs/ac., Mg around 650 lbs/ac, sulfur about 22 ppm and a pH in the mid to high 6s. We'll see. Maybe you are attributing over inflated values to the indices?

We've had this argument; suffice to say it's another example of sufficiency levels not accounting for the soil particulars and panicking the customer needlessly. Assuming the test is correct, and given the accuracy of many soil tests, I won't make that assumption.

So no, I'm not over-inflating the indices. Pretending the test is correct (again, something I won't do at this point), it's that I'm saying the index values are set without consideration for the soil itself and poor LGW got a fright from it for no good reason. It's why I find the sufficiency levels a very poor guide; they'll produce an overly alkaline sandy soil and an overly acidic silt/clay mix, which itself impacts the nutrient uptake efficiency and changes those "sufficiency" levels.

As mentioned, we've had the argument before and I'm just so not going there again.

A BCSR vs. "sufficiency level" argument? Hardly. I assume that is your attempt to deflect.

This test is wildly inconsistent and I wouldn't even say it's worth the paper it's printed on.

I disagree.

[T]here's absolutely no way reasonable sulfur levels (in this case, 22 ppm) and indices over 200 on calcium (in this case 3682 lbs/ac.) and magnesium (in this case 661 lbs/ac.) are producing a pH of 6.7.

This is an "argument" that can come to final judgment when the LL test is posted. As I said: We'll see.

It looks like my Ca and Mg are nothing to fret about. I do note that my K is low. I'd be interested in any fall fertilizer recs to help my mostly fescue lawn with that? It does make me feel good about my purchase of a quad-blade Honda mower, I think mulching in place my massive quality of autumn leaves should help conserve K.

That's more like it, and not internally inconsistent. So much for that first test's graphs, they were way off and scared you unnecessarily.

ME 16: A very dense soil (most likely very silty, but some clay types aren't out of the bounds of possibility). Once balanced, and that won't take much, you can simply re-test every three or even five years and be just fine. This soil isn't going to drift fast enough to send it into unacceptable territory very quickly.

pH 6.2: Much more like it. Your soil will probably balance at 6.4 or so (could be 6.3) when all is said and done. I suspect the original test was seeing the pH of the testing solvent (probably water); the difference between the two tests is a factor of slightly over three times as acidic.

OM 10.8%: Stellar, off the charts fantastic. Certainly mulch mow and mow all your fall leaves, but you don't need to make any special effort to raise this. You can certainly feed organically if you like, but there's no OM-based reason to do so.

Sulfur 12: Normal. This is a far cry from your old test...which I'd just throw out and forget you ever had done.

Phosphorus 454: Very high (your old test listed an index of 120; try 225+). Normal levels are around 200. Excess P isn't toxic until truly ridiculous levels, but you certainly don't need any more, and don't want any more. High levels of P start to block the uptake of other elements. I'd avoid phosphorus sources as much as possible for the foreseeable future.

Calcium 68%: On the nose perfect. No calcium is required or desired, but you don't have to specifically avoid calcium, either.

Magnesium 12%: On the nose perfect. No magnesium is required or desired. I wouldn't use much in terms of magnesium sources on this soil, but you don't have to avoid small amounts going down incidentally with another product.

Potassium 2.1%: Technically OK, but I don't like the soil shortage--and you have plenty of spare capacity in this soil for K storage. Personally? I'd raise this. We use potassium sulfate (sulfate of potash) to fix this, which you can get from some garden or landscape stores, or they'll order it for you. Get the granular, it's far easier to handle. Recommendations below.

Minor Elements: Did you steal my soil? Most minor elements are absolutely on the nose perfect. Even boron is perfect (a hair high, but that won't harm anything). I mention iron below, but only incidentally. Copper is technically high, but this won't be an issue.

Iron 229: Perfect. However, iron isn't toxic until absolutely ridiculous levels (50,000 PPM in most soils of normal pH). If you feel your grass color isn't quite as green as you wish, you can always use Milorganite at bag rate to very slowly raise iron levels over time and give the grass a quick shot of available iron.

Recommendations:

September 1: Apply 2 pounds of potassium sulfate per thousand square feet.

October 1: Apply 2 pounds of potassium sulfate per thousand square feet.

April 1: Apply 2 pounds of potassium sulfate per thousand square feet.

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

morpheuspa,

Many, many thanks for your counsel! The sleuthing to figure out lawn problems is fun, but it is still great to have some expertise to get things moving in the right direction.

I'm off to get some potassium sulfate! Hopefully this, combined with a bit more wisdom about seed varieties and overseeding windows will help the lawn get through next summer without suffering too much.

Potassium will enhance heat and cold resistance (somewhat), and seeding in fall will also help by assuring that the root systems are developed well enough by the following summer to do fairly well.

Most lawns actually don't have trouble with US winters if the species chosen are compatible with the location. Mine is often still green in February here in Pennsylvania (and not the southern part of it, either!)

But you'll still want to water the first summer as the grass isn't as established as it will be in future years.

Thanks, morpheuspa. I've been running into a problem where fall and spring were great and winter was Ok, but in Summer the heat and humidity combined with the extra shade that time of year was really thinning the lawn.

I'm overseeding very soon with more heat and humidity tolerant varieties. That's enough work I'd like to see some longevity in the results, hence my looking more closely at the soil.

Sorry, I'm not buying it, but I'll drop it.

LGW,

Still, near perfect soil. Regular N application is all that is necessary. Did you still want options for trying to loosen it up? Keep in mind there is no magic.

To satisfy my own curiosity: How long ago was that first test done?

yardtractor1,

Thanks for chiming in on this. I'm willing to entertain many perspectives on this sort of thing. While I'm no soil or chemistry expert, I get that understanding is a challenge regardless and being open-minded is almost always a good idea.

I'll consider that I just need to some aeration before my overseeding and that the weird weather pattern this year has left the soil a bit too crusty. With the next overseeding I'll shift my selection of varieties from most shade tolerant to most heat/humidity tolerant. As I told morpheuspa, the lawn was lovely going into May, but once the dog days set in the it was obviously hurting under the stress.

I'm also receptive to K being an issue since yellowing has been a part of the lawn's stress. The lawn is ringed by enormous trees, including maples and poplars, and for years the tons of autumn leaves have been carted away, possibly creation a K depletion dynamic in soil. I got a quad-blade honda and hopefully this fall I've save K and time by mulching the leaves in place.

The previous soil test was from about 11 months ago, done by a public university at a small mid-Atlantic state.

Thanks for responding.

The previous soil test was from about 11 months ago...

That helps explain a few things. Thanks.

Some observations in regards to your issues with your soil's physical profile:

High Mg soils tend to be tighter and to compact.

Some turf specialists report that additions of K to high Mg soils exacerbates the problem by increasing soil particle dispersion.

Common recommended remedies are:

Addition of OM.

This means incorporating finished (late stage) OM like peat moss, finished compost/manure (faster) or surface application of any form of OM (slower-much, much slower on finer or compacted soils). One thing that stands out to me is the level of your soil's OM and its status. Your soil tests reveal very little change in OM%. Unless fairly significant OM is added or the soil is in a cold climate, OM% will commonly fall. Compacted soils are low in air infiltration and gas exchange. This impedes the ability of the soil microbes in processing OM. Your OM status may be absolutely fine or it could reflect a very compacted soil where OM is not being properly processed creating additional soil health issues. Problem soils will not have an earthy smell, they have a more unpleasant odor. Consequently, I don't think incorporating OM is a default remedy in this situation.

Increasing Ca and the Ca:Mg ratio.

This is accomplished by adding gypsum to any soil and can be augmented with lime for low pH soils. Incorporation (aeration on an established lawn prior to application) can assist in effecting a deeper soil profile and slightly speeding change vs surface application.

Mechanical Aeration.

This is the employment of a core aerator (especially if an amendment is going to be applied) or a spoon aerator. Mechanical aeration creates holes and fractures the soil allowing for better water and air penetration and gas exchange. Although the holes and fractures are short term, the temporary improvement in the soil environment promotes rooting and fauna (e.g. worms) movement and infiltration. Over time, the increase in rooting mass and fauna/worms will improve the soil environment to where aeration is no longer needed or advantageous.

I agree with your inclination to mechanically aerate, but it's not necessary for seeding.

Good luck.

On the up side, lawngonewrong, you don't have a magnesium excess...and 8 pounds of potassium sulfate won't set off an imbalance, it's the rough equivalent of 170 pounds of elemental K per acre (an acre of soil weighs around 2,000,000 pounds). So that's not going to be the cause, or ultimate effect, of either tight soil or adding potassium respectively.

an acre of soil weighs around 2,000,000 pounds

That means 1,000 square feet would be about 46,000 pounds. How much finished compost would it take to raise OM by 1% ? What about something like alfalfa or corn?

I might start a new thread on this, but given amplification effects and soil changes, the math is far from linear. Or clear. Or consistent between locales and soil types.

yardtractor1,

Thanks! I'm really enjoyed your detailed response. I'm hoping to improve my lawn, but I also enjoy learning for its own sake and so all of this is great mind candy.

About my OM numbers:

My interest and enthusiasm has meant I have added additional OM since the last soil test. I made a half successful attempt at dormant overseeding and early in the season I added a few things to increase moisture retention/germination. This included about half a cubic yard of leaf compost/1k sqft, 20-30lbs. alfalfa/1k sqft, and (my goodness I sound over enthusiastic) 10lbs humates/1k sqft. Overkill and probably mis-directed, but it explains the tests, I think.

Going forward, I'm going to try mulching the massive leaf fall with my Honda mower. Doing this regularly should help keep the OM fairly high, though I have no idea about the actual math.

I also worked harder this time to get a representative soil sample, taking soil from more locations and spending much more time mixing my sample. Basically, I can't rule out sampling error as a cause in the tests' difference.

Compaction:

I'm pretty sure that's been an issue. This has been a lawn for over 100 years and it has seen many feet and other activity in that time. I think I have made some gains, both with last year's aeration and a schedule of shampoo/soil conditioner applications. This year areas that had suffered from heavy moss appearance in the past are now a fescue/triv blend. My hope is that by raking up the stolon carpet and overseeding I can give the fescue on edge. I'll try another round of aeration and a few more of the soil conditioner applications to further ameliorate compaction.

My big realization is that more than most, I need both a fall and spring growing season for new grass to really flourish. The summer humidity in MD/DC is truly awful and I think given that this is when the lawn is in its greatest shade means that June-August will always be a stressful season. And as morpheuspa suggested, the additional K I'm adding might help with stress resistance. I'm selecting varieties more for humidity resistance and less for shade, given that those are the most severe stresses. Here's to hoping that this combo of work results in a more successful overseed. In any case, I enjoy the experimenting so I never feel like this a waste.

This has been a lawn for over 100 years

That's more than likely where your high OM is coming from. On turf it is estimated roots produce up to 7,000 pounds of organic matter per acre per year. And it's the kind of OM that lasts 40-50 years in the soil, not the wimpy kind that turns to CO2.

j4c11,

Fascinating! This is just the kind of stuff I love learning. Do you know if the nearby trees, mostly poplars, some maples, and a few cherries, as well as the hedge plants, privet, honeysuckle, and cherry laurel, have any impact on OM? In any case, it sounds like from a soil perspective, I've lucked out. The humidity and heat are another story, though!

@lawngonewrong: I have the same Honda mower you have. It does great with leaf mulching. The leaves also clean the inside of the mower deck kind of like walnut blasting, so it will be nice and clean for winter storage.

I've read that dandelions don't like to grow where maple leaves have been mulched. Kind of interesting if true.

This year areas that had suffered from heavy moss appearance in the past
are now a fescue/triv blend. My hope is that by raking up the stolon
carpet and overseeding I can give the fescue on edge. I'll try another
round of aeration and a few more of the soil conditioner applications to
further ameliorate compaction.

Short on time, but STOP. If you have triv (or annua), do NOT aereate, That can spread it. I have found only 2 things effective with triv: kill it and all plant life within a foot around it with glyphosate or cut it and a surrounding area out with a sod cutter.

Also on aeration, what symptoms do you see that the soil may be compacted? Does water pool? Have you tried the screw driver test and what results? When you dig (dug for soil samples), what does/did your soil look like? What did the side of the hole look like (google images of "fertile/high tilth" soils and compacted soils)? How would you describe the texture? Sandy coarse? Clay like? Mucky?

There is no such thing as liquid aerator. If it is a surfactant, it can make compaction worse.

That means 1,000 square feet would be about 46,000 pounds. How much
finished compost would it take to raise OM by 1% ? What about something
like alfalfa or corn?

In 1000 sq ft of this hypothetical acre furrow slice, with no consideration to all the variables, a very ball park 550lbs of corn or 400 lbs of finished compost.

In 1000 sq ft of this hypothetical acre furrow slice, with no
consideration to all the variables, a very ball park 550lbs of corn or
400 lbs of finished compost.

I shouldn't post when I'm in a hurry and I shouldn't try to do math in my head,

The formula is: 267/carbon content of the applied material.

If corn has a carbon content of 32% then it would take 834 lbs of corn. add 15% water content, it's 959. Very, very much ballpark as it ignores the multitude of variables. Compost carbon% is just too variable to even guess, so i will not try to answer that, as I should have done when I first saw this question :/

lawngonewrong,

Also during your digging did you notice the depth and mass of the turf roots?

yardtractor1,

I've heard some of the warnings on aerating
and poa triv. The only issue with it is right at the lawn's margin in a
more shady area that used to be mostly moss. I've pulled a bunch of triv
and was going to rake up the remaining stolons to assure better
seed-to-soil contact. If I were to aerate, I do everything else first
and cover that patch last.

The screwdriver test shows no
problems. Branches fall all the time and get impaled in the soil to
something like 4 inches. Water does seem to collect on the surface, but
perhaps that is just since we've had very heavy rains this year? The
soil feels like a dense clay cake, though I am able to break it up it
seems to prefer dense clods.

The root mass in the soil sample struck me as skimpy. I would've expected deeper and longer, but I don't have good comparables.

I'll
consider skipping on the aeration and just trying to get the seed in
the ground. Noting what I said before, that June-August tends toward
turf murder here, having the longest possible growing season before that
is likely to make a huge difference in the future.

yardtractor1, great detailed writeup. One question - ppm on what test? (Especially for P.)

desirous,

Phosphorous is based on Melich III testing. I surmise from your question you are looking at SLAN. Keep in mind, SLAN values are sufficiency levels for "average soils" (approximately CEC 5 to 15), the higher the CEC, the higher the number in the range. Remember also that SLAN means additions may or may not (50/50) result in a beneficial change. Additions when numbers are below the range are expected to have a high probability of improving quality and growth.

When compiling this I made a concerted effort to, and to the best of my knowledge, all ppm recommendations are based on Melich III extraction/testing as it is becoming the default.

I've noticed some more edits that I'd like to make to clarify some things. Knowing me, this is likely to be a continuing process. So as not to drive LGW crazy with notifications, I may move it to a separate post.

Your welcome to comment there if there are other questions or points I need to clarify once I repost.