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Soil Preparation and Analysis

Subject:  puzzling results

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Captain 97

Stanwood, Washington

So I did a soil test in September and used the Langley soil calculator to try and balance things out and bring the levels of certain nutrients up. I just did another soil test in prep for the spring and found that not only did the things I add not bring any of my numbers up, pretty much all of the numbers went down across the board and my ratios are basically unchanged. The only thing that changed for the positive was the Boron and that was still nowhere near where it should have been. Any Thoughts? We had the rainiest January on record and I started my cover crop late so it never really got very well established. Did everything just leach out? Feeling like I wasted my time.

Here are my fall numbers what I added and the spring numbers My patch is 400SF

Potassium -
fall value 697 Added 10 pounds of 0-5-25 langley predicted value 783 actual Spring value 475

Phosphorus -
fall value 102 Added 3 Pounds of Triple Phosphate & 10 Pounds of 0-5-25 langley predicted value 148 actual spring value 87

Calcium -
fall value 1972 Added 2 bottles of liquid gypsum langley predicted value 6997 actual spring value 1631

Manganese -
fall value 3.0 Added 2 pounds of manganese sulfate langley predicted value 37.8 actual spring value 3.0

Boron - fall value 0.4 added 1 pound of borax predicted value 7.2 actual spring value 1.1

Predicted Ca:mg 10:1 actual 3:1
Predicted Ca:k 17:1 Actual 7:1
Predicted Ca:P 47:1 Actual 19:1
Predicted P:zn 13:1 Actual 9:1
Predicted P:Mn 4:1 Actual 29:1
Predicted P:Cu 26:1 Actual 20:1
Predicted zn:cu 2:1 Actual 2:1
Predicted mn:zn 3:1 Actual 1:3
predicted mn:cu 7:1 Actual 1:1
Predicted K:b 109:1 Actual 432:1
Predicted mg:k 2:1 Actual 2:1
Predicted Ca:B 972:1 Actual 1483:1
Predicted mn:fe 1:2.1 Actual 1:20


2/25/2020 7:36:07 PM

Little Ketchup

Grittyville, WA

Thanks for posting. Did you add lime in the fall/ what was your soil ph in september? How did sulfer do? I could write a lot but suffice it to say I believe my soil does get stripped of nutrients after five maybe six feet of rain ... Add anything soluble before that much rain. . .sadly not much remains. Very interested in this topic.

2/25/2020 8:20:20 PM

Pumpking

Germany

It is a combination of various effects:

- Manganese is easily transformed (oxidized) to MnO2, which is practically insoluble in water, thus large amounts of Mn added to the soil don´t show up as soluble nutrient after a while. Especially with higher pH this becomes a problem, whereas in acidic soild Mn remains rather soluble. Therefore, you better apply Mn as foliar spray or at least as soluble fertilizer in small amounts as the plant grows.

- Leaching by rain water: Have a look at sodium, this is one of the cations which gets washed out easily (like K and Mg) and its content dropped the most. The others dropped, too, but less dramatic because you had added them during soil prep.

- Have a look at the CEC, in the 2nd analysis it is lower (12 instead of 14), and the same applies to organic matter. Thus, I would guess you had taken samples for the 2nd analyses from down to deeper depths (another 1 or 2 inches deeeper, thus collecting more sandy soil and less of the organic matter containing top soil). Sand doesn´t hold so many minerals, and therefore addition of a larger portion of sandy loam to the sample would cause some rather proportional dropping of nutrient levels.

2/26/2020 6:55:05 AM

Pumpking

Germany

What I usually do: I add organic matter in fall before I sow the cover crop. Samples for soil analysis are taken in spring (to see what´s left after all the rain and snow has washed out things from my soil). Then I add the soluble minerals (such as epsom salts, borax etc.) in spring.

2/26/2020 7:00:37 AM

Captain 97

Stanwood, Washington

I posted both the fall and spring tests in my diary. Ph was 7.2 in the fall and dropped to 7.0 in the spring. The other interesting thing was that the organic matter almost halved. This is my new patch so it had quite a bit of new manure and new compost added in the fall.

2/26/2020 10:44:24 AM

DJ SpudKin

Nampa

My 2 cents are that if you have had a lot of rain or snow, the soluble nutrients could have leached. It is also very easy to have variation in the soil sample. You might give Western labs a call and get their opinion. Another soil test is probably the best way to get any confidence at this point. Going off of a petiole sample would be accurate also.

2/26/2020 10:51:42 AM

Pumpking

Germany

That´s what I addressed with the different sample depths used in fall and spring. However, another option would be thorough mixing with low organic matter subsoil during patch prep (in the time between the two soil analyses), which could also lower the percentage of organic matter in the sample (even though it did not lower the total amount of OM, just mixed some parts of it into the deeper layers of soil).

2/26/2020 10:53:43 AM

Orangeneck (Team HAMMER)

Eastern Pennsylvania

Matt, that your organic matter was halved is further indication that you went deeper when pulling the second sample than the first.

2/26/2020 11:04:38 AM

Pumpking

Germany

Yes, I agree with Orangeneck. Good to see that someone else shares my opinion which I had listed as the 3rd reason in my first post here.

2/26/2020 11:23:03 AM

Porkchop

Central NY

this is why you guys get paid the big bucks...I would probably test again?...it must be tough going from growing on your driveway to a garden...good luck captain...we'll be watching...

2/26/2020 1:22:49 PM

Captain 97

Stanwood, Washington

I would bet money that I didn't go deeper with my second test. I take my soil samples the exact same way every time. All of my manure and compost was tilled in before the fall test and then I did one till after I added the above mentioned amendments. I took the spring test before o filled. Personally I think leaching is the most likely. Having record january rain is saying something in this neck of the woods. It's still hard to believe I didn't at least get a little bump. I guess from now on I will not bother testing in the fall.

2/26/2020 3:29:05 PM

Marv.

On top of Brush Mountain, Pa.

Ever consider covering your garden with a tarp after you add your fall nutrients? No leeching. Take tarp off in early spring.

2/26/2020 7:14:45 PM

Little Ketchup

Grittyville, WA

I am already trying marv's suggestion this year. A foot or two of rain might be ok but beyond that, with three or four feet over the winter... it starts to get discouraging. For me, to have nutrients go back to zero in just two years. Thats my guess..based on observed results. So my guess is your soil test shows nutrient loss to excessive winter rain. With a plastic cover... loss would be limited to volatized ammonium and slight decay of organics... the only downside would be excesses for example sodium could eventually build up but you would get in place enough nutrients to hit 2k well before the sodium was a problem.

2/26/2020 10:43:56 PM

big moon

Bethlehem CT

I like the suggestion of the tarp. or you'll have to wait until spring with the applications. I believe many of the ferts you put down are in plant available forms and should not be expected to remain stable in the soil. They go into the soil in solution and stay there. The soil can hold them, up to a certain point (depends on how high you C.E.C. is) The plant takes them up with the water which is good, but they can also be lost through leaching. I know that borax is lost pretty quickly, through first hand experience. In my case I was very glad about that because I over applied. ( that's a whole other story)
Like pumpking said, In the fall I would work on my soil structure through the addition of organics etc. Perhaps correct the pH as well (if needed). Retest in the spring, then adjust accordingly.
I am not sure why your organic matter decreased.

2/27/2020 9:27:18 AM

Captain 97

Stanwood, Washington

The soil is extremely loose because I completely excavated out 12" of soil and added all the soil, manure and compost back in in layers tilling as I went. Perhaps that contributed to increased leaching.

Putting a tarp on in the fall pretty much eliminates using a cover crop. at that point I am thinking you might as well just wait till spring to apply your amendments.

2/27/2020 4:30:44 PM

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