March 24, 2010

Monday and Tuesday we aerated the greens. Aeration is one of the most difficult, and most labor and equipment intensive practices that we perform. It’s also the most important thing that we do.

This is what we did to improve the greens:

Before we aerated, we did a half inch deep verti- cut with the Graden machines. The verti-cut blades slice into the green and pull out thatch, which is the organic mix of living and dead plant material found at the top of the greens surface. Some thatch is good, as it cushions the growing points of the grass plant from traffic. But too much thatch slows drainage, and makes the greens slow and spongy. Fungi love thatch, so reducing the amount of thatch helps with disease control. The verti-cut blades also severe the bent grass stolons, or runners, prompting them to produce new plant buds. This helps increase the bent grass population.



Following the verti-cut we began the aeration process. The aerators pulled cores from the greens, approximately 3” deep and .5” in diameter. This process removes both thatch and soil, leaving a hole to be filled with sand. I will say more about sand later.



The clean –up crew came next. Two persons operate the “core harvester”. This machine is best thought of as a moving conveyor belt that moves the plugs from the ground to the bed of the vehicle it is attached to. Another team cleans what debris the core harvester leaves behind. The cores are taken to areas where fill is needed – such as along cart paths, low areas that are bare, etc. These cores will later be raked out and seeded with another grass.



Following clean - up, sand topdressing was applied with a tow behind top-dresser. We always do our best to put down enough sand to fill the holes. This is very tricky because the aeration holes are never perfectly uniform, and some areas of the green always need more or less sand. Sometimes it takes two topdressings to get all the holes filled.




I will talk more about sand now. The sand we use is spec’d for its size and shape, so that it firms without much compaction, while still providing pore space for air, water, and roots. It is also heat sterilized to kill fungi and weed seeds and prevent contaminating the green with disease pathogens and unwanted plants, such as clover, poa annua, or crab grass. The sand is a soil improvement, which makes for healthy, firm, and true greens.

After topdressing, we applied “good fungi” to the greens of the genus mycorrhizae. There are books written on the subject of mycorrhizae, but to keep this post simple and short, these fungi work symbiotically with the plant roots to take in nutrients, absorb water, grow bigger and deeper, resist disease, and make the plant stronger. These fungi are best applied in a manner that they can be worked into the soil root zone, and so aeration is the best time to add these.



Next we used a soft cocoa matt to gently drag the sand into the holes. When the weather is dry this is a very simple process, but with constant rain showers and high humidity, the sand was dampened and took a lot of extra work to matt in. Due to the wetness, all the greens will need to be dragged once or maybe twice again.



Over the next few days we will be going back and adding topdressing to the greens where the holes did not fill, re-dragging where needed to even out the topdressing application, and rolling to smooth and firm the greens. This is normal aftercare for aerated greens.

Aeration is really an investment. It promotes rooting, helps drainage, increases air exchange, increases soil microbial populations, adds pore spaces, reduces thatch, helps prevents diseases, and so on. Although none of us, especially me, likes the disruption, it still is the only and best way to renew the greens for yet another golf season.