Understanding Your Soil
Alush, healthy lawn begins with the soil that lies beneath it. Good soil is your first line of defense against problems, because it ensures that the grass has all the nutrients it needs to grow strong, win the competition against weeds, deny pests a home, and prevent disease. The best soil also ensures that water drains quickly enough so that the lawn doesn’t drown, but not so quickly that it dies of thirst.
How well your soil supports lawn growth and health depends on the balance of the four basic ingredients that make up any soil: air, water, inorganic minerals, and organic matter-the mix of decaying plants and insects called humus. The wrong balance creates a soil that doesn’t drain and discourages root growth, or one that drains too quickly to effectively hold nutrients. The right balance is a rich mixture teeming with beneficial life.
Lawns prefer loam for good reason. Loam provides a ready supply of nutrients to the grass. Those nutrients, like the soil structure itself, must be in proper balance to ensure that the lawn gets the food it needs, when it needs it. The three main nutrients you’ll encounter most often in discussions of lawn health are nitrogen, phosphorous, and potassium. But as essential as these are, they are only a few of the many nutrients present in healthy soil. An overabundance or deficiency of other key nutrients can create problems just as serious as an imbalance in the big three.
The nutrients available to grass roots will also be affected by the pH of the soil, which is the measure of how acidic it is. An imbalance in pH can occur when a lawn is not correctly maintained, or is improperly fertilized. When soil becomes too acidic or alkaline (the opposite of acidity), some nutrients become unavailable. It’s easy to fix an acidity imbalance, but detecting it early is key. Maintaining proper pH, along with ensuring the right balance of nutrients, is why any sensible lawn program starts with a basic soil test.
How well the soil supports your lawn also depends on how much soil you actually have. Topsoil that is more than five inches deep provides an excellent foundation for the typical lawn. But topsoil is expensive, which is why home builders and contractors often use two inches or less. That can translate to a lawn that struggles. So in addition to making sure your soil is supplying the proper nutrients to the grass, you’ll also need to determine how much soil you’ve got to work with. In most cases, it’s a good idea to regularly add organic matter on top of the lawn to build up the soil base, in a process called topdressing.
But whatever you do, always keep in mind that although you can’t see it, the soil underneath your lawn is just as important as the grass itself. It’s a living, breathing thing, and keeping the soil healthy is key to keeping your lawn healthy.