organic matter

Daniel Hahn asked an interesting question about organic matter. Talking about “variability between greens at the same site,” he wondered, “could you explain what your opinion is about the statement, if you think greens vary a lot in OM or if you see minor difference?

I’ve been making estimates of N mineralization from soil organic matter for the past few years using the method described by Gilmour and Mauromoustakos in Nitrogen mineralization from soil organic matter: a sequential model.

Turfgrass creates a lot of soil organic matter (SOM), also called humus, and the quantities of carbon (C) in that organic matter might surprise you. I made this chart to summarize the amount of C in the top 10 cm (4 inches) of a turfgrass rootzone.

I’ve made some updates to the standard OM246 report this year. The portion of the report with charts is showing four distinct things, and I showed examples and explained them in this video.

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.

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.

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.

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.

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.

I understand there are a lot of different ways to manage grass. One way involves measuring infiltration rate. That’s not the way I do it. There are eight things1 I do like to measure.