For the past few years, the USGA Green Section has been working with university researchers and industry experts on a project to develop a standardized protocol for organic matter (OM) testing. This protocol will cover how samples are taken in the field and how the testing is carried out in the lab. To date, each lab has been sampling and testing differently. This makes it difficult to quantify what the “ideal” range for OM really is. It’s also difficult for courses to compare between one another or to published research, unless they know for sure what methods were used to measure OM content.
Before we get too far, it is worth reiterating the importance of OM management. Some of the most disruptive practices performed on a golf course – e.g., core aeration, aggressive vertical mowing and sand topdressing – are done primarily to manage OM. These practices significantly impact the playability of the course and in many cases, revenue. However, OM content is one of the most influential factors on turf health and playability so the long-term benefits of these practices far outweigh the short-term disruption.
When OM is excessive, one can expect softer and wetter surfaces, shallower rooting, greater likelihood for disease and insect damage, and a host of other agronomic concerns. Although not as common, OM can also be too low, causing a loss of surface stability, reduced traffic tolerance and a soft, “shifty” surface.
During the past few years, USGA agronomists have sampled hundreds of putting greens for organic matter content and simultaneously measured several other performance characteristics. That process has allowed us to hone in on sampling and testing methods that produce consistent and reliable results. It has also helped narrow down an “ideal” range of OM for various turf species, rootzones and growing environments. As we continue to evaluate and gather more data, we will have a better understanding of how OM, turf health and other factors interact with each other to influence characteristics such as firmness, ball reaction, smoothness and traffic tolerance.
Perhaps the most practical use of this information will be to help superintendents communicate to stakeholders why they need to perform practices like aeration and topdressing, and how much of each is needed to keep OM in the desired range. At the highest level of maintenance, this information will help superintendents fine-tune their program to provide the best conditions possible with the least amount of disruption. If you would like to discuss OM testing or management in more detail, contact your regional USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director – znicoludis@usga.org
Paul Jacobs, agronomist – pjacobs@usga.org