Slate 2017 Soil Test

[Slate]

Area: ~6000SF lawn
Grass Type: New Construction - Sod Northern Mix ~1year
Mowing/Irrigation: Mow at tallest setting. Have been watering 0.5" (~45min), 2x/week when there has been no rain. Supplement with irrigation during rain events <1".

Moved in to the new construction last year, looked ok at the time we purchased but by the end of fall the yard was covered with weeds & grass did not fill into many spots. Coming out of winter it seemed that most of the yard was dead or had snow mold. Raked the whole yard to help with airflow and aerated. One week later, about June 1st, used starter fertilizer & crabgrass preemergent. Memorial day used 2 bags of milorganite. The company that aerated the lawn then came out unexpectedly and fertilized 1 week later @ 2/3lb N. (total ~1.4lb N within a week). Started watering deep & infrequently around mid June as temps were around 95deg.

Currently plan to aerate, compost, and overseed through a soil quality restoration program with the city this Fall.

Soil pH seems high, I took samples ~4-6" but reading the topic by andy I may have gone too deep into the subbase. I don't belive that I did since looking at the construction nearby is all clay with black topsoil above. We have a dog and I hope I didn't sample from a bad spot. Will be interesting to see results next year. Low OM I hope will be improved by composting this fall.

Appreciate your advice. Thanks.

[Slate]

I wanted to add that this area is known to have very hard water which may contribute as to why the soil is alkaline.

[Slate]

From the Soil Management Part II

CEC is different from TEC (“Total Exchange Capacity”) in that TEC accounts for what the capacity could be if the Hydrogen was replaced with primary cations. A little more sophisticated, it draws a better picture of the capacity in acidic soils. In alkaline soils, TEC and CEC are always the same.


Occasionally, the CEC can be overstated in tests. This happens when there is so much of a cation present that the soil has the cation present that is greater than what is bound to the soil. With a little practice, the soil test interpreter can spot likely cases of this situation.

My soil test seems to be a good example for this. Is this since all of the colloids have picked up the Ca, Mg, K, and Na. There is no room left for the Hydrogen to make it acidic? Could you explain the Other Bases (variable) shown on the Logan Labs report?

[TimmyG]

Slate, your image doesn't seem accessible.

[Slate]

[andy10917]

OK, where to start? The first thing that you need to decide is what program you're going to follow. The "city program" that you're considering will highly-likely not blend well with what we will recommend - our program is pretty intense and you can't lay a different program on top of it or aside it. Many people feel our aggressive program is intense and unorthodox. But it works very well.

You've made mistakes that will haunt you this year. Hopefully you either have the product bags you used or you remember what brand/product it was. The crabgrass preventer applied around 6/1 was ridiculously late for crabgrass and will do nothing to prevent crabgrass -- it should have been applied probably in early April when the Forsythia bloomed. The "haunting" is that the pre-emergent in the product will be effective for 3-4 months and will prevent overseeding of the lawn from succeeding.

And mechanical aeration isn't generally recommended here, as its effects are very temporary and yet it encourages buried weed seed to be dredged up and germinate.

So, to the soil itself...

The soil is NOT showing signs that the sampled areas are high in clay, or that they are a calcareous soil. Both of those conditions would show an inflated TEC and your's doesn't. A TEC of 9.26 indicates a soil that is just to the slightly-sandy side of a good Loam. The OM% of 0.85% is one of the lowest I've seen this year, and is just terrible. Yes, compost and mulched leaves will help -- with intense care on your part it may increase by 0.5% per year, and your target is 5%. Do the math - your goal is a decade away.

In the cations, Calcium and Magnesium are very high and Potassium is low. That's leading to the pH of 7.9 and that will not come down substantially, although some movement toward neutral is possible as the OM increases.

When the Potassium is low, I look at the Phosphorus number right away. If they're both low, we can avoid a lot of extra applications by using balanced fertilizers like 10-10-10 or 19-19-19. That's your angle. Pick a balanced fertilizer and post the NPK numbers, and we'll get you app rates and frequencies.

The Iron is low, but it wouldn't matter anyway - at a pH of 7.9 Iron is not available to plants. You will have to use chelated Iron, naturally-chelated products like Milorganite or the foliar FAS applications (read the articles on Iron).

In the micro’s, it’s Boron, Copper and Zinc. Get Twenty Mule Team Laundry Soap (grocery), Copper Sulfate (Amazon/EBay), and Zinc Sulfate (Amazon/Ebay) and apply each at three tablespoons/K every 60 days. Read the Micronutrient Application Guide for application specifics.

Do not expect that a Northern Mix lawn is going to spread and fill the gaps in your lawn. That only happens with KBG lawns. Your lawn will require overseeding and you need to calculate when the crabgrass pre-emergent will wear off to do overseeding. Take that into over to the Cool-Season Forum.