Outer Cape Water Quality Initiative: How do grass and natural lawns affect water quality?
Pesticides seem an easy target, but they really direct us to a much larger picture.
Grass lawns don't need to be stigmatized as wrong or bad but perhaps a new balance can be considered between grass lawns and natural (indigenous vegetation) lawns. The Outer Cape's thin soil conditions are brutal, acid and nutrient poor. The natural indigenous vegetation, like the residents, seem to thrive on the weather abuse.
Grass lawns are usually seeded on top of six to eight inches of loam or topsoil. Fertilizers are added to stimulate growth and all sorts of seeds will be successful there. The leaves will be enriched, sending out chemical calling cards to insects. To reduce unwanted "weeds" herbicides may be used. To discourage insects, pesticides may be used. Frequent watering, additional fertilizers and continued use of pesticides and weed killer may be needed. Indigenous animals will find no familiar food or habitat there.
Natural (Indigenous) lawns can be seeded with conservation mix over an inch or two of indigenous compost (obtained free from local transfer stations). We usually rake the compost in a little, seed and then add a once inch layer of mulch (also free from transfer stations) to mimic natural soil profiles.
When transfer stations chip brush, branches and leaves, bacteria and microorganisms begin the decomposition process. The new material can be used as mulch and the dark final product can be used as compost. The benefit of using natural decomposition products is that they already have indigenous pH and nutrient content and host a full range of decomposers that keep on working. Keep the small chips and roots in the natural mix to protect natural diversity in the insect/decomposer community. This mix also welcomes indigenous volunteer seeds and will evolve naturally.
The benefits of natural systems include: creation of habitat for indigenous animals; natural erosion control (all grass creates runoff); naturally filters out sediment and excess nutrients with root/leaf stem systems; never needs mowing; never needs watering (except for the first growing season; never needs fertilizer; never needs pesticides; never needs herbicides. The benefits of natural lawn systems for our drinking water quality include: water conservation; pesticide free, herbicide free and fertilizer free.