great site, my front lawn is 5 years old and I have many small sink holes, some still grassed and some bare.I believe they are caused from a poor soil foundation and larger stones beneath. It is east facing. Last year I top dressed with 75/25 soil/sand mix.I think I put to much on and killed some areas before removing it. It is now in fairly good shape grass wise, but even more dimpled. a) should I cut the grass first then add? How thick? b) what % sand and soil c) airate? d) spring fertilize before or after? Thank you
not warm enough for seeding yet. I would say cut to 2" height, areate, top dress, overseed, apply time release lawn fertilizer. If you want to be really diligent a soil test might be a good idea, to see where your mineral levels etc are, this will enable to you fine tune the fertilizer application
If it is "even more dimpled" it's possible that there are pieces of wood (construction debris or tree chunks from clearing) that are rotting out creating the dimples. Dig one up to see what it is and take it from there with jimmyq's process. Ralph
Hey Paul and Ralph, when would be the earliest we could over seed a turf lawn? Our baseball league starts April 7th. Tom at Evergro donated us seed, I am worried if I wait too long to spread it the players will tear it up before it germinates. Could it be put down soon? Sorry to be off thread. Jim.
Howdy Goodyard, The dimple problem will not likely be solved by topdressing if the dimples are deep. I would go with Ralph's suggestion of digging up a small area to see what is happening in the soil. What was existing on the site before the lawn was installed? If a large tree was removed, the dimpling may be from soil settling where the old tree roots have rotted and collapsed. If it is stones, old roots or construction debris, you may need to renovate the entire lawn to remove the dimples. You will also need to be careful when adding sand to soil, as it may create an impenetrable soil. I would suggest a soil/compost mixture for topdressing, or topdressing with a soil mix that closely matches the existing soil. The maximum depth of topdressing I would add would be a half an inch, and only if the lawn is aerated, one quarter inch otherwise. The height of cut depends on what variety of grass you are growing. Most lawn grasses can be cut between 2-3 inches. Bentgrasses need to be cut much shorter, from 1/2 to 1 inch. I would not change the normal height of cut you are using, unless it is too low for the variety of grass. Fertilizer for lawns...hmmmm. Do you intend to feed the grass plants, or do you intend to feed the life in the soil? Question for Jim: What variety of grass did Tom at Evergro donate? I would seed on the first sunny day, provided the field is not too soggy to walk on. Are you able to provide a light topdressing after seeding?
"...within 10 years (conservatively) the organic amendment will have decomposed; one is then left with the original soil, which will have subsided and compacted during this time. You can see evidence of this practice by looking at older residential lawns; the lawns slope away from sidewalks and driveways and are inches below grade of surrounding surfaces." http://www.puyallup.wsu.edu/~Linda ...ltural Myths_files/Myths/Compost overdose.pdf
Good article Ron. We definitely must take care when adding amendments to our gardens and landscapes. Getting your soil tested is a great practice. However, a standard soil test will provide a lot of information about the soil, but it does not tell the whole story. It does not break down the OM content into its constituent parts, nor does it tell you what soil organisms are present and at what population levels. You need a soil food web assay for that. I wonder if the lawns that Dr. Chalker-Scott observed had been maintained organically, or if they were maintained with the current chemical paradigm. A chemical maintenance program tends to disrupt the soil microorganism profile. It is the soil microorganisms that help improve the structure and fertility of the soil, and when our practices disrupt that process, soil can settle and compact. I am a fan of topdressing with thin layers of good, high-quality compost for established lawns that need a boost. For a permanent lawn installation, if the food web assay comes back noting a severe deficit of soil life, adding that soil life back in, and ensuring the soil life remains healthy is a good practice, even if it means adding a 4" layer of high-quality compost and incorporating that into the existing soil. I would tend to avoid incorporating materials such as sawdust, peatmoss and bark into the soil, as these materials will decompose and settle over time.
