Lawn Chemical Addiction & the Clover Alternative

This page provides a Web version of an article written by David Patriquin in 1989 for Between the Issues, the news magazine of the
Ecology Action Centre . An updated version was published in 1998.

The intensive use of fertilizers and pesticides on lawns and turfs provides a good example of how our society is addicted to agrochemicals.

In its natural state, lawn, turf or pasture consists of a mixture of grasses, wild white clover and a half dozen or so herbs that is largely self-fertilizing. As well as beautifying the environment, it performs important ecological tasks: minimizing dust and siltation of waterways; absorbs water quickly and releases it slowly, minimizing flooding; finally it acts as a biological filter, purifying the groundwater by absorbing chemicals in rainwater and excess nutrients deposited by pets and gardeners.

This system works because of the complementary activities of grasses and clover. Grasses produce a mat of fine, fibrous roots in the top 10-15 centimeters of soil giving the lawn its spongy water-absorbing texture. Grass is a heavy feeder and if not overfed by fertilizers, it quickly absorbs soluble nutrients. Clover is a legume with nodules on its roots.The nodules enable the plant to use gaseous nitrogen from the air to make protein. When clover tissues die naturally, or from cutting or grazing, decomposition releases the nitrogen making it available to grasses.

Photos at right illustrate clover roots with nodules (expanded). The nodules contain bacteria which are able to "fix " gaseous nitrogen from the air, turning it into protein and chlorophyll. When the clover decomposes, the nitrogen is released and is available to grasses.

If not supplied with fertilizer nitrogen, grasses are dependent on clover for nitrogen, and a natural balance is reached whereby clover satisfies the nitrogen requirements of the lawn and grasses ensure that there is not an excess of nitrogen.

As well, clover's deep-growing roots take up nutrients that reach below the roots of grasses. Clovers accelerate the weathering of rock, which releases mineral nutrients such as potassium into the soil, and increases the depth of topsoil. They also grow better than grasses in mid to late summer, when grass growth is inhibited by heat and a lack of moisture. A mixture of clover and grass withstands drought much better than pure grass alone.

Addiction begins with nitrogen fertilizer

When a manufactured nitrogen fertilizer such as urea or ammonium sulfate is added to make grass green up faster, these beneficial interactions begin to fall apart. The dense root mat of grasses enables them to absorb fertilizer much faster than clover; so grass grows above the clover and shades it. Nitrogen fertilizer inhibits formation of nodules on the clover, so the clovers take less nitrogen from the air.

Grass becomes a competitor with the clover rather than being dependent on it, soon outcompetes it and the clover disappears. The lawn is then reliant on fertilizer to provide nitrogen, and where once a little sufficed, a lot is required. Use of commercial nitrogen fertilizer acidifies the soil, so lime must be added to neutralize the acidity.

With the clover gone, there is an unoccupied "niche" or ecological space available for deep-rooted plants and it is filled by broad-leaf, deep-rooted non-legumes such as dandelions and plantains. We consider these plants unsightly, so herbicide is applied to kill the broad-leaf plants, including any remaining clover.

Then there are no deep-rooted plants to recycle the nutrients and water that moves below the grass layer. So the lawn requires more water, and more fertilizers have to be added, including more nitrogen, and probably potassium and phosphorous, and more lime. More is required and more is lost. The lawn which once was a purifier of water becomes a source of contamination.

Inefficient recycling of nutrients, and heavy applications of certain nutrients but not others, result in mineral imbalances and thatch accumulation which make the grass more susceptible to pest damage, so insecticides and fungicides are needed. These lead to their own cycles of addiction.

The final result is to convert a lawn that was at one time an inexpensive beautifier and water purifier into an intensive input system that is expensive to maintain, and contributes to environmental deterioration, which is paid for by society at large. Addiction is guaranteed by the "weed and feed'" fertilizers, which simultaneously fertilize the grass and kill the clover. On a scale of 1 to 10 for agrochemical use in agriculture (10 is high), intensive lawncare comes in at 10.

Why we do it

So why do we do it? We have moved from the Garden of Eden to a state of chemical warfare with nature right on the home front. If there is a better way, why didn't we or why don't we use it? I suggest two reasons: first, we got into it gradually, imperceptibly. Beginning with inputs of nitrogen fertilizer which had immediate benefits by no immediately discernible detrimental effects, ecological processes were gradually and progressively dismantled and more and more inputs were required. Each input on its own was beneficial, but created further addiction.

Second, in the process we created an industry on which we have become dependent. Hundreds of millions of dollars are spent every year on lawn and turf management in Canada and the industry is still growing. A precisely analogous process has taken place in agriculture at large. Beginning with the use of nitrogen fertilizer, we have created ecological addictions and generated industries and bureaucracies to service them, and we are now "dependent" on them for employment and investment profits.

While a changeover to ecological lawncare might be disruptive initally, a full changeover to ecological lawncare would create just as much employment locally, and would keep more dollars in the community. It's really change that we resist, not the principle.

Clover-based ecological lawn care for the homeowner

Agrochemical addiction begins with the use of nitrogen fertilizer. Getting off the addiction begins by replacing chemicals with clovers and organic fertilizers. This means sowing clover if it is not present, or finding ways to increase it if it is present in small amounts. Don't rely on natural invasion - this typically occurs by gradual expansion of a few initial clumps which appear unsightly and can take a long time to spread evenly throughout a lawn. Dispersed clover blends in with the grasses, and confers its benefits more evenly than clumpy clover.

To establish clover in existing sod, sow clover seed in spring or early fall. Use Dutch White, not the larger forage types such as Alsike or Red Clover. The grass should be cut short and raked first. The seed can be broadcast by hand. Fifty milliliters or 40 grams per 100 square meters is plenty. Seed can be mixed into the soil by raking with a stiff rake, but there should be good establishment even without that. If seed is sown in early spring while there is still frost, it will drop into small cracks opened by freezing and thawing. For a new lawn, use about 1 part by volume of clover seed for 15 parts of grass seed, however sow it separately. If mixed with grass seed, the smaller, dense clover seed will tend to settle out.

The soil organisms that infect clover to produce nodules are ubiquitous, and usually it is not necessary to introduce them. However, if absolutely no clover is present on your lawn or in the neighborhood, it's advisable to spread legume inoculant with the seed. It can be purchased with the clover seed. To introduce inoculant into an already established lawn, it can be mixed with compost or soil and broadcast with the seed, followed by raking with a stiff rake to open up the soil a bit. Then trample or roll the lawn lightly and water it well if it is dry. If the clover is present but in minimal amounts, lime or phosphorus may have to be added. Soil analysis will help. It's best to add phosphorus in a less soluble form, for example, as bone meal or rock phosphate, as this will be less inhibitory to biological processes than superphosphate. Compost is a good source of phosphorus.

The most important fertilizer recommendation is to use nitrogen sparingly. Fish fertilizer or compost can be used to give the lawn an early-season boost. These fertilizers also provide phosphorus, potassium and trace elements. The single, most beneficial time to apply a nitrogen-rich organic fertilizer is late in the fall when the grass stops growing, but is still photosynthesizing - this "dormant feed" strengthens roots and encourages early greening the next spring. More organic fertilizer will be required on lawns recently established on low quality topsoil, than on old lawns. It's best to incorporate lots of mature compost (1-2 inches) when preparing new soil for turf. Use a general purpose seed mix, not straight Kentucky bluegrass.

Clover needs lots of light, and will not establish well in shady areas. After sowing seed, the lawn should be mown regularly and fairly close (1.5-2") which favors clover over grass; once the clover is established it can be mown higher again, and should be mowed high (3") though June, July and August. Grass clippings should be left at least until after the first rainfall, which will recycle many of the nutrients. When grass clippings are removed, they should be composted and some of the compost returned to the lawn. Use of a mulch mower is best.


Weeding can be focused on the unsightly weeds that don't blend well with the grass. In this region, those are mainly dandelion and plantain. If plantain (right) is not present initially, it can be kept out by practicing vigilance in removing new plants; seeds do not disperse far from parent plants but seedbanks are persistent and once established, create a recurring weed problem. Wild violets behave like plantain.

Dandelion produces light seed that is widely dispersed, but it is non-persistent, thus it can invade in large numbers from outside sources. Removing dandelion in adjacent areas can reduce that; plan to remove seedlings a few weeks after the main seed rain in late spring.

Where removing weeds leaves a large gap, add some ryegrass (not rye) or clover seed (or a mix of both) mixed with a bit of soil or compost to the bare patch, and step on it to compress the soil slightly; this will draw moisture up by capillary action, which helps germination. Both ryegrass and clover germinate quickly, surplanting new weeds.

Establishing a good balance of clover and grass reduces the amount of handweeding needed by about 3/4 - to me clover is a must, especially for my back!