The addition of compost to our lawns has been promoted throughout North America by many advocates of the organic movement including Paul Tukey in his excellent book “Organic Lawn Care Manual”. It is an excellent book promoting management of our lawns in a safe and sustainable manner. Paul has also initiated an international coalition of for-profit and non-profit organizations promoting environmentally friendly lawn care and resource conservation called SafeLawns.org.
In the “Organic Lawn Care Manual” Paul recommends “blanketing the lawn with a quarter to a half inch layer in the spring and fall in the first year… Don’t apply so much that you smother the grass; it is possible to burn lawns with compost, especially if you apply it in the heat of the summer. Tips of the grass should always be poking up through the compost when you’re done”
Below are a series of photographs of some lawn compost applied at less than 1/4″. More is not better in this case, and more would have caused burning of this lawn, and would have cost more. I have to stress that it is very important to understand the nutrient content and the electrical conductivity of the compost that is being applied.
I have also included a photograph below of a lawn that had approximately 1/2″ of a compost applied, where after a number of weeks, the grass was still struggling to grow and the compost was still very obvious.
It is important to understand what is in the compost. The nutrient content and electrical conductivity of the compost that will dictate the compost application rate. On the SafeLawn.org blog, Paul recommends the following when considering compost. “Do a simple germination test prior to your purchase. Simply put a few seeds of annual ryegrass into a container of the compost, keep it watered, and wait a few days to see if the seeds germinate readily. If the seeds germinate and the grass appears to grow quickly, then you probably have safe compost. If the seeds don’t germinate, then either the compost likely isn’t “finished” or it’s tainted with pesticides.”
This is a classic mistake made by many. A germination test is an indicator of the electrical conductivity of the compost (see my previous blog), and not necessarily an indicator of whether it is finished or tainted with pesticides. The electrical conductivity of a compost (a measure of the soluble nutrients in the compost) is a function of the material being composted, and not whether it is finished or not. In fact, if a compost is being produced under cover in a manner that conserves the nutrients and protects them from being washed out of the compost, the electrical conductivity of a finished compost can actually increase as the compost “finishes”.