# First Soil Test



## TravisT (Oct 20, 2019)

Submitted my first soil test last week and received my results today. Would love any recommendations:


----------



## g-man (Jun 15, 2017)

Logan takes me a bit longer to process since they do the calculations in lb/acre at 4in depth. Mentally calculating, P and K are low. A balance fertilizer will be appropriate. Follow the guide  for rates of what to apply to your soil.

One item of note is the ratio of calcium to Mg. I normally don't comment on it, but yours is atypical. I think you should do gypsum to increase your calcium without affecting your pH. In the past, did you apply lime to this soil?


----------



## TravisT (Oct 20, 2019)

G-man, thanks for the reply. I've been using your sticky to try and decipher the results, but have yet to come to any solid solutions.

The 4" depth I think was due to what I told them, not the norm. I believe it said the default was 6" unless they are told otherwise.

I did add lime last season, but I did it completely blind based on the recommendation of neighbors. I doubt they had anything they based this recommendation on.

The only other thing I did last year was the fall nitrogen blitz using urea. I'm glad to have a soil test to now be able to make informed decisions.

I will keep reading but plan to go with a balanced fertilizer for now. Looks like due to being on the high end of the pH spectrum, iron applications should be FAS. Aside from the gypsum (what rate would you recommend?), does it look like any other applications are necessary in the near term?


----------



## g-man (Jun 15, 2017)

The lime likely raised your mg levels. It also could push your pH above 7. How much you did?

See what you find locally for the balanced fert. Lowes, HD, Walmart sell it.

7.1 pH is not too high. My yard is close to 8. Some of the iron you have will still be available via the roots at that level. So, don't sweat the FAS. Do a bag of Milo or carbonX or Scott GreenMax if you want more color.

I will need to get back to you on the calculation of gypsum.


----------



## TravisT (Oct 20, 2019)

Honestly don't remember how much lime I put down last year. That was before I started getting serious about this and logging everything.

The fertilizer shouldn't be a problem. I've picked up 10-10-10 in the past from southern states. I'm sure there are other sources as well. 46-0-0 was harder to find, so I ended up ordering it online last year. Still have some left, and may not need it given the other elements are lacking.

I have some more reading to do on the Milorganite. Don't understand exactly what it is when compared to other fertilizers. How does that compare to a balanced fertilizer? What does milorganite have that greens up the lawn that a normal balanced fertilizer doesn't?


----------



## Pete1313 (May 3, 2017)

You can put down 20-30 lbs/M of gypsum every 60 days. Separate the P and K apps a few weeks apart from the gypsum. Note that it will take multiple apps over years to significantly change the Ca/Mg ratio and the need can be debatable. I do it, and am seeing benefits. A lower ratio and the soil has the feel of being tighter and seems compacted due to the imbalance.

These were my base saturation % in 2016, a Ca:Mg ratio of 1.39:1 (your ratio is 1.11:1)


These were my base saturation % in 2019, a Ca:Mg ratio of 2.33:1


Over that period I added 96 lbs/M of gypsum. Since that last test in 2019 I added 63.75 lbs/M of gypsum and will know the effects of that in about a month once I get my soil test done, but as you can see it is a long term deal. When calculating, 30 lbs/M of gypsum(21% Ca and 17% S) should add 274 lb/acre of Ca, or around 205 PPM of Ca at a 4" depth, although actual test numbers will most likely show less of an increase. Adding gypsum should displace some Mg, as well as some other cations.


----------



## g-man (Jun 15, 2017)

Pete gave me the number I needed.

Logan calculated you need 747lb/acre
747lb/acre = 747lb/43.5ksqft= 17lb of Ca/ksqft

Gypsum is 21% Ca, so 17/.21 = 82lb/ksqft of gypsum. Like Pete said, apply it every 60 at 30lb/ksqft rate until you get to 82lb/ksqft.

Milorganite is a biosolid. It is a byproduct of the Milwaukee sewer treatment plant. It is expensive in a per nitrogen basis. But it is a good source of iron that is available to the root at higher pH. The NPK changes since they can't control their inputs. I think it is currently 6-4-0.


----------



## Ridgerunner (May 16, 2017)

@Pete1313 and @g-man When did you two get to be such refined pencil pushers? So nerdie. :lol:


----------



## Pete1313 (May 3, 2017)

Ridgerunner said:


> @Pete1313 and @g-man When did you two get to be such refined pencil pushers? So nerdie. :lol:


I've always geeked out when it comes to numbers! :lol:



g-man said:


> Pete gave me the number I needed.
> 
> Logan calculated you need 747lb/acre
> 747lb/acre = 747lb/43.5ksqft= 17lb of Ca/ksqft
> ...


Regarding the recommendation of 82 lb/M of gypsum, although that will get you close to the desired level of Ca reported by Logan labs, due to your high levels of Mg, your Ca:Mg ratio will only change some. Getting the Ca number to 2603 lb/acre will bump the meq to around 9.75 for the Ca. Ratio wise, assuming a bit, the Ca:Mg ratio will go up somewhere around the 1.5:1 to 2:1 ratio.

This is where some of the debate comes in, you need to over apply Ca(gypsum) in order to get those numbers to change an appreciable amount and whether or not it is worth it. I have seen some of the positive effects on my soil. Starting out in 2016, my soil had the consistency of thick fudge when wet, concrete when dry. The tilth is improving now, but at a cost of 160 lbs/M so far of gypsum and I am not done yet. I personally think the number is worth working on, especially on a higher CEC soil.


----------



## TravisT (Oct 20, 2019)

Ok, so I put down my first application of gypsum today at about 30lb/ksqft. I'll do 2 more applications at the same rate 60 days apart. By that time, I'll probably be ready to retest.

I'm trying to pick apart both the test results and the recommendations so I can understand all this better, so bear with my questions...

First, the soil test results show desired values - is this what I should use as my targets? I'm also using the GDD DarkSky spreadsheet that I came across on this site. On the "Soil Deficit" tab, I entered my test results after converting lbs/acre to ppm (multiplied by .5). Unless I'm reading the spreadsheet wrong, I'm getting different targets.

For example, the MLSN target is showing 625 ppm and the MLSN + removed is 628. This is less than half the 1301 ppm (2603 lbs/acre *.5) target given by the report above. Is my conversion correct? Which should I use?

Also, how can you tell how much NPK you need? Based on the spreadsheet (again, if I'm reading/understanding it correctly), it shows my usage of NPK is approximately 5.1 - .65 - 2.61. How does this equate to using a balanced fertilizer? From what I have read, the nitrogen drives the grass to demand/use the other elements, but if the usage ratio is not 1:1:1, then wouldn't an unbalanced fertilizer be best?

I'll stop there for this post and keep reading to understand this better. Again, I hope this isn't taken the wrong way - I don't doubt the knowledge that's been shared in any way. I'd just like to understand it better, and am conflicted on the info I have.


----------



## Ridgerunner (May 16, 2017)

There are two major soil analysis philosophies. One is SLAN, or a variant, MLSN, both of which target nutrient levels necessary for acceptable plant growth. The other is BCSR which targets ideal ratios between certain nutrients that are believed will result in most fertile soil. Logan recommendations are based on BCSR. Kinda apples and oranges.

It appears you have already read up on SLAN/MLSN.
This is BCSR: https://www.agvise.com/wp-content/uploads/2015/02/SSSA-Cation-Ratios.pdf
or a shorter read: https://sesl.com.au/blog/what-s-wrong-with-the-base-cation-saturation-ratio-concept/


----------



## Ridgerunner (May 16, 2017)

A pretty good point/counterpoint:
https://sturf.lib.msu.edu/article/2012jan24.pdf
Joel Simmons became pretty defensive thereafter.
http://www.earthworksturf.com/no_more/


----------



## g-man (Jun 15, 2017)

@TravisT don't try to compare the target values from Logan Labs to MLSN. It is to completely different approaches.

How much P or K a lawn needs is really hard to tell. What the studies did is say, hey that lawn over there looks really nice, what is the P and K for it. They repeated this for 10k golf greens. They graph the data and then looked at the distribution. Then noticed, 80% of the good looking greens had a value of P greater than X. So for a lawn to look good it should have at least that. And that's how MLSN got created (21ppm for P).

But now we have studies in the works (Dr. Kreuser and Dr. Soldat) of building lawns with 0ppm and then testing how it looks at 1ppm, 2ppm, etc. Here is an image of them writing a P in the lawn by just applying phosphorus. What these studies are trying to find is, what is the real low limit.


__ https://twitter.com/i/web/status/1122877252138622977
Soil, nutrition and turf can get you into a rabbit hole of reading a ton of research at night in the winter months (from what I've been told).


----------



## TravisT (Oct 20, 2019)

@g-man and @Ridgerunner I appreciate all the time and effort you spend here sharing your knowledge. I'm still digesting all this info, but I'm learning.

Thank you


----------



## TravisT (Oct 20, 2019)

Another question - I put 4 bags of milorganite down (.9lbs/ksqft N) last weekend. If moving to a balanced fertilizer (i.e. 10-10-10), when/how often should I re-apply?

Temps are still cool here (50's today, 70's for the next two days, but snow in the forecast for early next week), and the grass isn't growing yet. I have read that you don't want to push growth during the summer, but what about leading up to it (now)?


----------



## g-man (Jun 15, 2017)

The main problem with Milo right now is that it needs microbial activity. You applied almost a pound per ksqft. If you had warm weather and the grass growing, you should wait at least a month for your next N application.

Milo also has P in it. So you could just add K via SOP to get the NPK you need.


----------

