I am often struck by the accusations and recriminations leveled at the lawn within discussions concerning vegetable gardening–here it is called a feudal remnant. In my own practices, I use grass to maintain soil fertility and reduce soil erosion.
My observations of urban lawns (specific to Seattle where I make my observations) is that they are generally in sad shape. In part, contractors and developer practices play an important role. By and large topsoil is removed, or compacted by heavy equipment, and post construction, 2 or 3 inches of soil is brought in and sod is laid atop. Dig up a section of lawn, and more than likely one will find a root system 2-4 inches thick. That’s about it.
The lawns I grow in my vegetable beds develop root systems much larger. Dig up a section of lawn, and the root system will measure over 18 inches. It shouldn’t take much convincing that a lawn grown in 2-3 inch of soil is a much different lawn than one grown in 2 to 3 feet of sandy loam. The most obvious is reduced need for irrigation. A layer of topsoil 2 feet thick has a larger water holding capacity than one 4 inches thick, just as it supports a more extensive root systems.
Perhaps less obvious, but equally important is that the act of mowing produces a surplus of solar energy in the form of grass clippings, and of a more favorable nitrogen-to-carbon ratio for the vegetable garden than straw–grass gone to seed, and often placed in fall beds, when I seed mine to lawn. By mowing the lawn, and letting the clippings lie, one is preventing the grass from going to seed and essentially keeping the lawn in a constant state of vegetative growth. Each mowing puts a little bit of organic matter back into the soil.
Which lawn do you believe stays green through the summer without irrigation or fertilization?
You see, many of the accusations leveled against the lawn–the need for irrigation, fertilizers, and gas powered equipment–are in fact a criticism of technique.