OM246

Soil tests

We provide soil testing services for clients around the world through Brookside Labs, and have an active research program in the area of turfgrass nutrition, soil and plant analysis, and sampling methods.

OM246

Measure exact topdressing effect, and requirement, by checking total organic matter by depth.

Maximum soil organic matter, not minimum, should be the goal

I like to test the total organic material at the surface of a turfgrass rootzone in autumn. Doing the testing in autumn captures the majority of the growth, accumulation, decomposition, removal, and dilution that has happened during the previous year.

The inexorable rise of soil organic matter

One of the many valuable things I utilize from OM246 testing is what I call the organic matter accumulation rate. I’m actually referring to the net accumulation rate—how the total organic material in the rootzone would change if no topdressing had been applied.

Soil organic matter should be invigilated

A substantial amount of organic material accumulated at the surface of a Tifdwarf bermudagrass putting green at Rota in the Northern Mariana Islands. I don’t recall if I read this exact statement, or if it occurred to me when I read something else about invigilation.

Three things you can do right now with OM246 data

You can use OM246 test results to learn how total organic matter compares to general recommendations; better yet, you can evaluate how maintenance practices, growth, weather, and decomposition are changing total organic matter at a single site; and then there is what I call the killer feature of this testing: you can make a precise and site-specific calculation of organic matter accumulation rate and sand topdressing requirement.

Total organic material accumulation rate and sand topdressing requirement

When the total organic material is known at time A and at time B, the accumulation rate can be calculated. By accounting for the sand that was applied between time A and time B, another accumulation rate can be calculated: the organic matter accumulation rate independent of sand application.

All the organic material

Everyone understands the segmentation of OM246 samples by depth. That is in the name of the test, after all. Most people understand that OM246 testing is a mass loss on ignition of all the material.

Organic matter change over time

I've been working on an explanation of what OM246 testing is. The main point I wanted to make in part 1 is that the change in total organic matter between two measuring dates shows the result of topdressing, and growth, and weather, and microbial activity, and coring, and scarification, between those two dates.

Another talk with Joe Gulotti

Joe Gulotti, host of the acclaimed Talking Greenkeeper podcast, called me to talk about aeration. We talked about that, discussed the OM246 method for measuring the exact effect of cultivation and topdressing, and managed to discuss Thai food, Kawana, soil sample lab prep, and why Joe is sleeping in the studio.