Where skin meets grass

By Dr. Dave Minner

Q: At our local community college, 24-inch wide strips of sod are being removed to realign all edges where the skin meets the grass. All the edges have a lip and are somewhat jagged after so many years of edging. We are removing 18 inches of sod to make straight lines again and then installing the 24 inches of new sod. How much of the aglime should we core out to replace with black dirt before installing with new sod? Is it even necessary to core out the aglime? Will the sod root down through aglime?

Jon Baedke, Smitty’s Lawn Landscape Garden, Fort Dodge, IA


A: Agricultural lime or aglime is sold as a bulk material to raise the pH of acidic soil and is readily available and widely used in farming communities. It is basically a calcium carbonate material with most of the particles in the range of 8 to 60 mesh size (mesh 8 about the size of BB’s and below mesh 60 is like face powder). The best quality aglime for neutralizing acid soils is usually lighter gray to white and finer material; however those that are preferred for a baseball infield skin are tan/buff/red colored to reduce glare and have a more grainy appearance with less dust. Aglime is widely used as a baseball infield skin material because of its low cost, wide availability, and good playability under wet conditions. On the down side, aglime can become hard and dusty when insufficient water is used to manage the skin surface.

In my opinion the sod should be placed on at least 6 inches of good topsoil. That would require excavating out most of the aglime since the aglime base pads are usually 4 to 6 inches deep. In projects like yours or whenever the skin field is reconfigured, there is a tendency to lay sod directly on top of the aglime because it requires less work. I suggest that you avoid this practice and put in a growing media that will create aggressive turf growth and a clean edge between the grass and base path.

Too often I see lazy contractors place sod directly on top of aglime or other infield skin materials when renovating infields. With adequate water the sod will root and begin to grow into the aglime and will look satisfactory for a while, perhaps the first season, but in time the aglime (think about it, it is lime with a very high pH) provides a poor growing media; droughty and low in organic matter with a pH high enough to induce deficiency of other nutrients such as iron.

Grass growth is stunted and turf appears lighter green when grown on aglime. So my preference is to remove the aglime and replace it with good topsoil before sodding. It is interesting to note that weeds like goosegrass and spurge will readily grow in aglime fields but when it comes to finely manicured turf aglime is not a good growing media. Lips that form from blowing aglime also requires routine removal to promote aggressive turf growth at the edge where skin meets grass.

I’ve also notice a trend toward all grass base pads between home and first and home and third, especially when coaches and players are managing fields. They like it because there is less lip and skin to manage. I didn’t like this non-traditional field look at first, but after putting in and managing a few fields with grass base pads, I certainly do understand the attraction; it is easier to mow grass than to manage skin and lips.

If you are converting from aglime base pads to grass base pads it is extremely important to excavate out all of the aglime and replace it with a good loam soil before sodding. Don’t fill the base pads with sand in hopes of making it drain better because it will dry excessively in the shape of the old base pad and differential water of the strip usually never happens. Just use a good local native soil to fill the excavated base pad and then topdress with sand and compost to smooth the surface. It’s always a struggle to keep the soil materials separate where the skin meets the grass.