In my last update I touched on turf site reconstruction, and since then some have asked for more details on the finer points of the process. Whether the goal is reconstruction, renovation, or repairs, proper site preparation is one of the most crucial steps for any establishment project. This is true regardless of the chosen establishment method, whether it be broadcast seeding, slice seeding, hydroseeding, sodding, etc. The time and effort invested in good preparation are comparatively minimal, especially since successfully established turf can persist and perform indefinitely with regular maintenance. Once a stand is in place some practices, especially remedial practices, may be difficult or impossible from either a physical or financial standpoint. In other words, there are no shortcuts that provide an effective substitute for thorough site preparation before planting.
Grading is often a primary component of construction or reconstruction projects. The key to grading is thinking about how water will behave on the site, especially stormwater that may come in large quantities in a short period of time. Eliminate depressions to minimize puddling and pitch the grade away from buildings. Shape and use slopes to direct water to integrated drainage features. All debris (wood, stumps, boulders, etc) should be removed, not buried, to prevent future issues such as settling, fairy ring, poor drainage or localized dry spots. Be sure to match the contour of the rough grade (sub-grade) to the desired finish grade – inconsistencies will result in topsoil being too deep in some areas and too thin in others. Especially avoid altering grade around established trees, either cutting or filling. Critical, fine roots of most trees grow very close to the soil surface. Cutting will cause direct damage to these roots, while filling will further separate them from atmospheric oxygen which is vital to root function and outright survival.
Take all available steps to minimize soil compaction from construction and site preparation activities, as both equipment and foot traffic can cause serious compaction on bare soil without appropriate care. This may include removal and stockpiling of topsoil during construction activities, and performing any mixing of soil or amendments away from the planting site. Compaction caused during site preparation will have significant, lasting effects on turf health, persistence and performance. Compaction can also inhibit infiltration and drainage, promote runoff, and impact the performance of pesticides and fertilizers. The end result will be continually stressed turf that requires increased time, labor, material, and budget resources to maintain. Therefore, priority should be given to avoiding soil compaction and remediating any existing compaction prior to planting.
When spreading topsoil and building a root zone, remember projects that include root zone tillage are a rare opportunity to incorporate fertilizer, lime and other amendments into the system prior to establishment. For informed additions start with a soil test for chemical properties (pH, nutrients, etc) of the topsoil and test any organic amendments separately. Consider also testing the physical properties (texture, organic matter content, etc) of the topsoil to get an idea of expected soil behavior and to ensure compatibility with any additions of soil or organic material.
As for the seedbed (or sodbed), the objective is a firm (but not compacted) granular surface that promotes stand uniformity and seed-to-soil contact. Rake or drag to prepare a consistent surface, break up any large clumps, and remove any remaining debris. In some cases, light irrigation to settle the seedbed and create a more receptive surface is the final ingredient prior to seeding or sodding.
Lastly, take note that we are getting into the tail end of what is considered the ideal establishment period for most parts of Massachusetts, and shorter days and very cool nights seem to be advancing the clock. If you have involved construction or reconstruction projects still looming, now is the time to get on it.
Submitted by: Jason Lanier