Managing Surface Organic Matter

Golf turf playability and performance lies at the heart of golf course Best Management Practices that protect and preserve water quality. Optimizing playability demands a well-drained, firm playing surface able to withstand traffic and demonstrate resiliency during normal play. The key to achieving these goals lies in the management of surface organic matter.

Turf is a perennial plant system that increases surface organic matter as a result of turf growth and management (Figure 1). Organic matter accumulates at the surface from the development and deposition of plant parts such as leaves, stems, and roots. Underground plant parts, such as stems (rhizomes) and roots, cycle as living, dead, and decomposing organic matter.

The accumulation of organic matter in the top 3 to 6 inches of a turf system increases over time and provides nutrients and water holding capacity, as well as Increasing the resiliency and traffic tolerance required of playing surfaces. However, when too much organic matter accumulates at the surface, it can restrict infiltration of water and when wet does not dry easily into a playable surface. This can reduce the effectiveness of fertilizer and pesticides and increase runoff volumes from the turf surface. The following NYS BMP statement is based on this premise:

Manage the surface accumulation of organic matter to maintain a permeable system that minimizes runoff and maximizes subsurface retention.

Turfgrass species, fertilization, and soil properties influence turf growth and organic matter accumulation. Assuming proper growth is maintained, organic matter accumulation in grasses could be managed through less invasive cultivation and light applications of sand throughout the season. A light application (0.1 to 0.2 inches) of material applied and integrated into the surface of the turf dilutes the organic matter and creates a physical matrix that functions as a soil.

Topdressing is often performed in conjunction with some form of cultivation that simply makes a hole. Research at the University of Nebraska by Professor Roch Gaussoin shows clearly that topdressing frequency (even when compared to use with cultivation) had the greatest influence on organic matter accumulation. (Figure 2). Less invasive cultivation with solid tines provides minor disruption to create space for topdressing to serve the purpose of dilution and creation of a pseudo-soil matrix. Some research suggests the amount of topdressing sand that might be needed over a growing season increases. However, many opportunities to reduce organic matter accumulation exist via more precise N applications and more regular use of plant growth regulators. Ultimately, the goal of proper dilution is to ensure adequate infiltration while preserving sufficient retention of the turf system to prevent leaching.

To summarize the good, better best practices for managing organic matter accumulation are as follows:

  • A good organic matter management program utilizes a calendar-based approach to N fertilization and plant growth regulator use and maintains a light/frequent topdressing program in combination with some form of cultivation.
  • A better organic matter management program casually monitors turf growth rate, applies N based on growth potential (demand driven), applies plant growth regulators on a regular basis, and maintains a light/frequent topdressing program with less invasive cultivation applied during the season.
  • A best organic matter management program measures clipping volume through the season, applies N based on growth potential (demand driven), applies growth regulators on a growing degree day formula, and strives to apply topdressing at a rate that carefully matches growth, finally utilizing cultivation to maintain surface infiltration.