THATCH BUILD-UP CAN BE A SERIOUS PROBLEM IN A LAWN, but, unfortunately, most people, even many lawncare "professionals" don't know what thatch really is and/or don't know where it really comes from. Let's establish the basics first.

Thatch is a layer of dead organic matter at the surface of the soil and at the base of the grass plant. This layer is made up of dead roots, rhizomes and "some" lawn clippings which have not been broken down.

A layer which is greater than about 1/4" to 1/2" is too much and should be dealt with appropriately. Thatch is beneficial under this level, but over 1/4" to 1/2" it keeps valuable water and nutrients from fertilization from ever reaching the soil. In addition, it is the perfect breeding ground for disease and pests which will harm the lawn even further.

You can check your thatch layer thickness by pulling up a section of sod or taking a core sample. Look right at the base of the grass blades where they come to meet the soil.

You will see a brown matted section of dead organic matter. This is thatch. You will know that you have a serious problem if you see very few live roots extending beyond this layer and if the sod pulls up fairly easily in a nice uniform strip.

Or course, if the thatch layer is over 1/4" to 1/2" thick and roots are decent, be happy - but take care of the thatch problem.

Contrary to what some may tell you, thatch is not directly caused by leaving clippings on the lawn. This can be a factor, but, if you have a healthy lawn and well balanced soil, clippings will not be a problem.

When does it become a problem? When you begin using chemical fertilizers and pesticides, herbicides, fungicides....well, you get the picture. These products, although they *may* provide a quick fix to aesthetic problems in your lawn, will certainly cause even greater "behind the scenes" damage that will lead to even more damaging problems in the future.

The biggest problem is that these chemicals raise the acidity levels in the soil. Therefore, even if the chemicals don't directly kill off any beneficial insects, micro-organisms and/or earthworms (and most of them do), the high acidity levels of the soil will push them out anyway.

Most of these little helpers like pH levels near neutral. Without these helpers, dead roots, rhizomes and clippings cannot break down efficiently, and thatch buildup occurs.

Also, without earthworms and aerobes, aeration of the soil comes to a halt resulting in compaction of the soil. Most plants - besides weeds - do not grow well in compacted soils.

Moreover, without the breakdown of the dead organic materials many of the nutrients that the lawn needs are not being produced. In short, your lawn is slowly dying. Chemical fertilizers mask these problems by providing a nitrogen "fix".

This causes a deep blue green color of the grass blades making them look "healthy" when in reality they are starving for the micronutrients they need to properly flourish.

Now that you're completely depressed, how do you fix it?

There are a couple of methods you can use:

• The old fashioned way to eliminate thatch is to rake it out or use a dethatching machine or verticutter to slash it out and rip it up. This is still a viable solution, but keep in mind that this causes a certain amount of stress to a lawn that may not be completely necessary. Also, the factors that caused the thatch build-up in the first place must be taken care of. This means eliminating chemical applications and probably adding a lime application to raise the pH levels back to normal. Moreover, if you intend on fertilizing, you must switch over to an organic fertilizer that will maintain the critical soil balance that your lawn needs.
• You could instead use a liquid organic dethatching application which is easy to apply and is much cheaper (in the long run) than renting a dethatching machine or hiring someone to do it for you and causes much less stress to the lawn. In addition, it works by adding the organisms that were missing in the first place, thereby helping to eliminate those initial causation factors. If you choose this method, first you should try and rake out any LOOSE, dead clippings from the lawn. Don't break your back doing it. You're not trying to rake out everything, just what comes up really easily.
• You might also choose to aerate beforehand since this really should be done with either method to alleviate soil compaction concerns (I highly recommend this approach). Once this is done, just apply the liquid dethatcher at the recommended dosage and intervals).

A number of companies manufacture and sell liquid dethatching products. I'm not sure that any one of them is more effective than the others.