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Help me Interpret my Logan Labs Soil Sample Please

10 years ago

I have 3 raised beds and have never gotten a soil test. I'll give a breakdown of them and then hopefully you guys can tell me what to do.

Two of the beds are about 5 years old and were built with Mel's mix and have been amended with compost every year. These are wooden 4x4 beds that are 2 2x6's tall. These are the "Raised Bed N" and "Raised Bed S" on the soil sample. "Raised Bed S" has almost the same results as "U Bed" because I topped it off earlier this year from "U Bed" because I was planting it then.

The other bed is made from steel and is 2' tall. I filled the bottom half with a garden soil mix from a local landscape supplier. It is a mix of sand, soil, and compost. On top of that I mixed in compost from a few sources, rice hulls, and peat moss. This is "U Bed" on the soil sample. A friend helped me build it a few years ago (more on that later).

I have added compost that I make 3 times because the steel bed seems to drop about 4"-6" each year. My compost includes chicken litter, cattle manure, horse barn clean outs and wood mulch. It is 2 years old and screened before applying so there aren't any large wood chips left.

I have used Neptune's Harvest and Tomato Tone as fertilizer and mulched with straw last year.

The beds did really well the first year but weren't as great last year so I decided to do a soil test before I did any amending. Last year was a bad year for everyone in my area so it could be weather to blame not my soil. Regardless I'm sure it can be better so Please Advise!

The 4th sample (David's) is my friend that is a metal fabricator and built the steel bed for me. He was impressed with my beds after year 1 and built some for himself. His initial results were poor but things got better as the season progressed. [Post from last year about the problem.[(https://www.houzz.com/discussions/new-raised-beds-vegetable-plants-are-dying-and-or-yellow-please-help-dsvw-vd~3117323) Please advise on his as well and maybe he will build you a steel bed (probably only if you pay).

The obvious thing to me is that I need to raise the calcium. Someone suggested lime for this but I was afraid it would increase the PH too much. Any option to increase calcium would be great. I'm assuming if I do use lime that it should be calcitic since my magnesium is high. Would Gypsum be a better idea?

The organic matter seems high. Should I back off on the compost when the soil drops this year? Is it possible I need more nitrogen?

Thanks!

Comments (3)

  • 10 years ago

    I didn't miss this in my rounds, I'm just thinking about it a bit. I'll give you a full answer a bit later this evening.

  • 10 years ago

    OK. I argued with myself about how much adjusting to do, and the answer is decidedly "some but not a great deal." These soils are in very good shape.

    David's is the easier of the two. It's like Mary Poppins...practically perfect in every way. I'd absolutely avoid phosphorus in his beds, and use nothing with any magnesium in it. Both are excessive, but not a problem (although excess P can cause vegetables to be somewhat bitter and chewy).

    His yellowing and failing veggies last year were probably from raw compost, or poor hardening off. Compost is, actually, completely unnecessary this year.

    Your beds are a little more complicated. For the most part, what I said for David's goes for yours as well. Except in your case, absolutely avoid phosphorus sources. Your levels are sky high. Ditto with magnesium.

    OM levels are very high, but that's not a concern (my gardens are at similar levels from having mulch applied every year). So you can back off on the compost if you like, but if you don't, there's no problem with that (except that the soil will settle faster and further if you use the compost).

    With good pH and not exactly low calcium levels, I'm hesitant to do too much fiddling about. Only the U bed is even faintly out of range, and for vegetables, that isn't really out of range (most of them flourish in slightly more acidic environments than grasses do although there are plenty of exceptions).

    I'm going to advise 15 pounds of gypsum per thousand square feet now and again in October when this year's crop is removed--but if you ignore that recommendation, it's no big deal.


  • 10 years ago

    Absolutely no reason for adding gypsum. In fact, add nothing but a nitrogen source. You've got plenty of everything else, pH is fine, sodium is not high.