How Humates Show up on Soil Tests

[andy10917]

I had conversations with Susan S. (owner of Logan Labs) and Bill McKibben (national author on Soil Testing) about how the use of Humates should appear on soil test results. It was quite interesting to see how their expertise lined up with my experience over the the past 4 years - far closer than I expected.

My direct reason for the conversations was to see if my soil test results lined up with their expectations. I was unsure whether the final-stage Humic Acid Carbon would "burn off" during Loss-On-Ignition (LOI) tests used to measure the Organic Matter on a soil test, and whether it would show up also on the TEC number.

The answer was "Yes", with some qualifications. It can affect both numbers, but they cautioned that the use of diluted liquid applications would be a drop in the bucket when compared to 2,000,000 lbs/acre of soil (at 6" test depth). I told them that my experience lined up with that assertion - I found that liquid products were far less-effective than granular products derived from Leonardite. I mentioned that we were using granular products, at 4-5 lbs/K annually, and at those levels they should be measurable at the 18-24 month point.

The interesting thing that they both brought up was that the effect of increasing the soil microbial activity that Humates cause would also by measured by the LOI test, so a larger microherd (biomass) would show up in the OM numbers - I hadn't considered that.

They also said that while they're fine, Humates shouldn't be a replacement for mulched leaves/compost/Peat Moss. When I mentioned that members just don't have the appetite for years of "doing it the right way", they regaled me with war stories from their professional jobs and chuckled about how it's not limited to homeowners.

I also found out that there is a new book coming out in September from Bill McKibben - his other one is on my mandatory reference list. Hopefully, I'll pick up some new stuff from the new book.

So,the application of 4-5 lbs/K of Humic Acid annually to the soil should show up (over time) andon soil tests as a measurable increase in both TEC and OM%. I don't think that you're going to see leaps and bounds in the numbers - I haven't, but every bit helps and I see a change.

[Dargin]

Those must have been some fun conversations. It's very exciting to hear that we'll see measurable upticks of OM and TEC over time. I was on board for the increased water holding capability alone.

Probably too early to tell, but I did notice that my iron app really seemed to uptake strong shortly (maybe 2 weeks?) after my first HDG app. Didn't plan it that way, just happened. I don't recall ever seeing the lawn this dark green under similar weather conditions, and that's even after bouncing back from a quiick dip into drought stress after the apps (uneven watering). It was just my same old 3lb/k app.

Is "The Art of Balancing Soil Nutrients" the book you referenced?
Apparently it's written so muggles can follow along. I hope so.

[andy10917]

Yes, the book is the one you referenced.

And Yes, Humates are excellent at keeping the Iron available for the lawn - it's on my list of things-to-do to come up with a way to build the chelation that occurs into a regimen, but the current list of experiments is as much as I can pay attention to. That said, you are experiencing one of the effects of Humates (especially Humic Acid).