The Green, Green Grass of Home

Despite their naysayers, lawns remain the choice of the vast number of householders. “I miss the wind, I miss the sunlight, I miss the smell of flowers and freshly cut grass,” exclaimed Canadian astronaut Bob Thirsk just before returning to such earthly delights after six months on the International Space Station.

Nevertheless, perhaps it would be as well to take a fresh, greener look at lawns and their culture. Most urban lawns have been cultured on good loam – at least four to six inches of it – over relatively broken subsoil. In the suburbs, new subdivisions have been built of former farmland. The topsoil was first bulldozed into heaps. The exposed subsoil was pounded by heavy machinery into a hard impenetrable pan. What soil wasn’t sold was spread back perhaps a couple of inches thick. Sod was then laid over this unwelcoming matrix. The result was probably advertised as “landscaped,” a travesty in horticultural terms but a welcome one in realtor-speak. Subsequently, culture has relied of irrigation and fertilizer, plenty of both. The latter, horticultural heroin, carried by runoff from poorly applied irrigation, is increasingly being fingered in pollution problems. For example, the massive summer algae blooms in Lake Erie have been caused by phosphorus in corn and lawn fertilizers, according to a recent report by the International Joint Commission (IJC) for the Great Lakes.

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Nitrogen fertilizers – the ones that give the green oomph to lawn grasses – are another serious problem. Less than one-third of the nitrogen applied as fertilizer typically makes it into crops, explained Nicola Jones writing in Nature (vol.501 p.291). But with the increased demand for food and in the U.S. the notorious demand for ethanol “green” fuel has resulted in increased fertilizer use. No less has the demand for green lawns. In the days prior to commercial fertilizers, how did lawns stay green? They were top dressed with rich, black topsoil two or three times a year. Special, high-usage lawns such as those for bowling, tennis or croquet received similar dressings of sifted compost. Once a year lime might be applied to balance acidity and release nutrients otherwise “locked up” in the soil. Such old ways are returning to favour. Weed-free topsoil is now being widely marketed for just such lawn topdressing. Lime has always been available but the more modern granulated forms are an improvement over the powder of days gone by. Commercial compost is another matter – if the animal manure was not composted efficiently, a good dollop of weed seeds may persist in it. This is definitely not what a good lawn needs. The availability of modern irrigation systems has all too often resulted in their excessive use. Although “electronic leaves” are available to monitor rainfall and consequent application, most systems continue to be operated off a simple timer. These apply water whether it is needed or not – usually not. Turf stays healthy when receiving a half-inch of water every three days. This penetrates deep into the soil and the grass roots follow it down. Thus during drought conditions, the grass is better able to resist desiccation. Some five decades ago, famed fertilizer company Scotts based on Marysville, Ohio, proudly displayed a magnificent lawn fronting their head offices there. Sprinklers played heavily, generous applications of fertilizer were applied. Visitors were shown how, under a single layer of sod, stretched a pad of solid concrete. The aim was to show what modern methods could achieve. Whether these were sound environmentally was never questioned.