Before laying sod or seeding your yard it is critical that you prepare your soil. A little extra effort before installation will result in decades of a happy, healthy lawn that is much easier to maintain. A properly prepared seedbed will help your turfgrass lawn become established more quickly and will require less irrigation.
A couple of concepts that are necessary to grasp when preparing your soil for turfgrass are infiltration and drainage. Infiltration is an indicator of your soil’s ability to soak up water making it available for root uptake before filtering down to the water table. Drainage refers to how quickly water moves downward through the soil. Determining how well your soil drains is fairly simple. Dig a hole that is about 12”-18” deep and 12”-18” wide and fill it with water. After it drains completely, refill it. Note how long it takes for the water level to drop. Optimal drainage is about 1” per hour. If drainage is much slower, fungus and diseases can develop. And if drainage is too fast, a lot of water will be wasted.
Compaction from heavy equipment and native soil type are the main determinates of your soil’s infiltration and drainage rates. Whenever possible, keep heavy machinery away from planting areas.
Compaction, infiltration, and drainage is affected by how much clay is in the soil. Clay soils hold water more than sand or silt. However, compaction prevents infiltration. Too much clay in the soil inhibits internal drainage, but too little clay prevents the soil from holding water long enough.
NOTE: The top of the soil, when full settled, should be around 2 inches below cement edges
Remove Debris
Rocks, dirt clods, sticks, and anything larger than ½ inch can cause problems. Remove any debris from the seedbed.
Tilling and Blending Additives into the Soil
If a soil test determines that your soil mixture is not ideal, steps can be taken to improve it. We recommend infusing your soil with nutrients by adding composted organic material. An ideal soil mix contains approximately 20 to 25 percent organic material. To add this to the soil, begin by tilling up the top 6-8 inches of the soil bed. Spread organic material in a 2-3 inch deep layer and mix in by tilling the soil again. Repeat this process if more organic material is desired. Chanshare Farms recommends adding up to 1 pound Nitrogen per 1000 square feet of a 16-16-8 fertilizer with the compost. Tilling the soil will loosen up the ground allowing much needed water and oxygen in. And the additives will give your new sod a tremendous nutrient boost and help your sod’s root system explode downward into the root zone quicker.
Organic material that is not fully decomposed is not nearly as beneficial to the soil as that which is fully composted. The organisms that do the job of decomposing organic material require a great deal of nitrogen. So, it’s much better to let organic material decompose separately rather than deprive the turfgrass roots of nitrogen. Most cities have recycling programs that provide fully composted material.
Salty Soil
Many soils in the arid West contain higher than normal salt levels. Commercial fertilizers (with the exception of phosphorous) tend to increase salt levels. Heavy fertilization is not recommended or required. Care should be taken to apply the minimum amount of fertilizer needed to maintain lawn health. With proper drainage, salts can be leached away from plant roots as water moves through the soil and into the subsoil.
After tilling, rake the seedbed. Raking the soil will smooth the seedbed. Turfgrass sod tends to accentuate the small hills and valleys that may exist in the planting area. Take great care to smooth the ground. After raking the soil several times, water the bare soil. This allows you to check your sprinkler system’s water patterns and encourages weed germination. Weeds sprouting prior to sod installation gives you a chance to eliminate them before laying your turfgrass.
Water Conservation
Modifying your soil correctly will conserve water and encourage healthy turfgrass. Chanshare’s turfgrass has thrived in most environments in the Intermountain West. Whether there is a drought or not, correct soil preparation is the first key to a water-conserving lawn. Improper soil preparation hampers water conservation and the development of healthy lawns. When considering a sprinkler system, Chanshare Farms recommends that Mammoth Gripper head clamps and spikes be used to stabilize all sprinkler heads. Stable heads can increase water distribution efficiency by 10 to 20 percent.
Final Grade
After the final grade, the settled soil should be at least two inches below the cement edges.
Watering the bare soil several times fulfills a threefold purpose. This will settle the soil. It will encourage weed seeds to germinate allowing weeds to be removed BEFORE sod installation. Lastly, this gives you a chance to check water patterns and adjust sprinklers to ensure even watering.