Organic Lawns, Healthy Soil
By Bill Kohlhaase, Planet Natural
Here’s something of a Zen puzzle for you. The key to a healthy lawn is healthy, organic soil. And the key to healthy soil is a healthy, organic lawn.
Confused? Don’t be. Organic lawn care starts and ends with healthy soil, soil that is full of nutrients for both grass and the microorganisms that call your dirt their home; soil that is not compromised with toxins and synthetic chemicals that destroy those microorganisms. And nothing contributes to the health of your soil more than a thick, rich organic lawn, one that returns organic nutrients to your soil. In this win-win situation, organic lawn care can actually give you a more vibrant lawn than you would have with regular applications of commercial fertilizer.
To put it another way, the organic lawn is a self-sustaining lawn.
Take it from Paul Sachs, whose books on organic athletic fields and golf courses, have started something of a green playground revolution. “When you feed the life of your soil, those growing populations of microorganisms begin to accomplish many jobs that now consume great amounts of your time, money and energy.”
Sachs lists the advantages of encouraging microorganism populations in your lawn’s soil — rather than killing them with herbicides and pesticides — by showing what they do. Microorganisms “…fertilize, by fixing nitrogen from the air, mineralizing soil organic nutrients, generating carbon dioxide (the plant’s most needed nutrient), and dissolving mineral nutrient from rock; de-thatch, by decomposting thatch and other organic matter into valuable nutrients and humus, which in turn increase the water and nutrient holding capacity of the soil; aerate the soil; and control many lawn pests and disease problems by competition and predation.” And these are only some of the advantages that a healthy population of microorganisms bring to your lawn’s soil.
In brief, having healthy soil that’s rich in microbial life saves you money, time and effort; it means less fertilizing, less watering, less time and money spent on weed and disease control and, equally important, it means less harmful chemicals being spread into the environment through run-off and pesticide application.
But how do you encourage microorganisms to multiply in your soil? Simple. Start adding more organic material in the form of compost and grass clippings. And stop adding herbicides and other pesticides.
The first step in creating a healthy lawn with an abundant supply of beneficial microorganisms, whether it’s a new lawn or an established one, is to test the soil. The soil’s acid-alkaline balance — pH level — is as important for growing grass and its supporting soil microbes as it is for growing vegetables. Levels of nitrogen, phosphate, potash and other nutrients are also important and worth testing. (It’s also good to know how much organic matter is in your soil, but not all lab analysis will tell you this.) Having the proper pH level will encourage grass to grow in vibrant fashion. Healthy grass, with its roots spreading deep and wide providing places for oxygen to collect, with its blades growing well-nourished before natural mulching back into the soil, will provide great conditions for soil microbes.
Easy, accurate and inexpensive pH testing kits are available for home use. Follow the directions carefully and, depending on the size of your yard, take several samples to a depth of five inches from different locations (this also applies if you’re sending samples for more detailed analysis into your local extension service or other testing service). Most cooperative extension services will ask you to combine your samples into one after removing grass, roots and other living matter. Follow their directions to the letter (you can find a link to your state’s cooperative extension service here).
Soil pH for lawns should be neutral to slightly acidic, a measured range of 6.5 (slightly acidic) to 7.0 (neutral) is ideal. Slight variations are acceptable. Alkaline soils with a reading higher than 7.5 may lead to a condition known as iron chlorosis, an inability for the turf to take up iron. This results in grass that is shading towards yellow, not the rich green that we lawn lovers prefer. Some grasses, according to the Kansas State University Research and Extension, are more susceptible to iron chlorosis than others, with Bluegrass and Zoysia grass being very susceptible and Tall Fescue being the least. Buffalo grass, Bermuda grass, and perennial ryegrass, they say, falls somewhere in between. Organic sources of sulfur can be applied to reduce the alkalinity of soils over 7.5 and increase intake of iron.
Avoiding chlorosis is one of the reasons why pH testing is crucial. You don’t want to go to all the trouble putting in a new yard only to have it come up pale and sickly. Another reason is to encourage microbial growth. Soils close to neutral pH are best for this. And soils with a pH near neutral allow grasses to readily take up the macro nutrients they need. You may have plenty of phosphorous in your soil but it will be unavailable to your grass if the pH reading of your soil is 6.5 or lower.
Your testing agent or test kit instructions will have guidelines on just how much lime (if your soil’s too acidic) or sulfur (if it’s too alkaline) you’ll need to apply. Either way, adjusting soil pH is a tedious process that involves follow-up testing after time for the additives to be taken by the soil. Lime is especially slow to be incorporated into your soil and it’s easiest to apply lime to soil before a lawn is planted or sod laid. If you are adding lime to an established yard, try aerating first before applying and then water the yard lightly. Repeat the aerating process again a week or so after. The key technique required for successfully changing the pH of established lawns is patience.
No matter if you’re installing a new lawn or working with established turf, use high-quality additives. Oyster shell lime, because it’s produced by a living source, will neutralize acidity more quickly than crystallized sources. Dolomite lime often contains magnesium (about 11%, but this can vary) and can add this important mineral to your soil. If your soil tests high in magnesium, try aragonite, a lime supplement that doesn’t contain magnesium.
Pelletized lime makes for easy handling and spreading. Burnt or quick lime will move through soil quickly but it is highly toxic and should be avoided by the organic gardener. Hydrated or slake lime can also be hazardous and difficult to spread.
Your county extension agency’s soil test will also yield results for macronutrients (phosphorus, magnesium, potassium and calcium) and, possibly, micronutrients (zinc, copper boron and iron). The organic gardener who makes thorough applications of compost to his yard won’t have to worry about adding micronutrients. And once a healthy yard is established, the regular return of grass clippings, along with a yearly application of compost, will naturally recycle macro and micronutrients back to the soil. But if testing has shown your soil to be badly deficient in certain nutrients, it’s time to supplement. Again, quality additives are the key. Those derived from kelp or other ocean sources will provide well-balanced nutrients as well as modest amounts of nitrogen.
Nitrogen should always be applied carefully. Using fertilizers high in nitrogen on new lawn soils may discourage seed germination while encouraging the growth of weeds. After germination, excess nitrogen will encourage blade growth at the expense of a deep root system. Frequent applications of nitrogen on established lawns can lead to shallow root growth and an inability to over-winter or survive drought. According to the Ohio State University Extension Service, fall and late fall are the best time to apply nitrogen in most areas. Spring and summer nitrogen applications of the sort promoted by commercial lawn services lead to disease, rapid growth requiring frequent mowing, shallow rooting, weed encouragement and other problems.
Safe, organic sources of nitrogen — corn gluten meal, blood meal, cotton seed meal and a variety of organic manures — can be worked into the top four to six inches soil well prior to planting to maximize integration and avoid run off. These same sources, minus the manures which may burn grass with too much nitrogen (even if they are labeled “composted manure“), can be applied to established lawns that are in critical need of nitrogen. Integrate them into the soil through watering and or aerating. Comprehensive natural lawn fertilizers, ones that contain nitrogen, phosphate and potassium (potash) should have a rough N-P-K ratio of 3-1-2 or something close, say 8-2-4 . Always apply inclusive fertilizers according to directions. Be careful not to over fertilize with nitrogen. No more than roughly one pound per 1,000 square feet of yard is needed. The best way to add nitrogen to your established lawn and encourage microbial growth is to spread compost once every year (more on this below).
In addition to nitrogen, your lawn needs macronutrients to stay healthy. Phosphorous aids seed germination in new lawns and encourages strong, pervasive root growth in established lawns. If testing shows your lawn to be significantly deficient in phosphorous — and traditional, non-organic lawns that were treated with high amounts of nitrogen often are — you should add a good organic source such as fish emulsion or seaweed derived fertilizer, bone meal or soft rock phosphate. Again, the amount you apply is dependent on your test results. Phosphorous, if not entirely absorbed into your soil can be damaging to the environment. Apply it carefully, and in small amounts. You don’t want it running off your lawn and into natural water courses where it can contribute to algae blooms and other aquatic problems.
Potassium is health food for your turf. It makes your lawn more resistant to heat, cold, drought, disease and the wear-and-tear from frequent use. Again, seaweed and fish emulsions are good suppliers of potassium, as is greensand and some mineral supplements like sulfate of potash-magnesia (K-Mag). Wood ashes have traditionally been used to raise potassium levels in soils but are especially prone to run off and can raise soil pH in the quantities required (wood ash may also contain other toxins).
Most of the other essential macronutrients, calcium and magnesium, will be supplied by the good-quality organic supplements you use — principally seaweed and liquid fish emulsion – to increase phosphorous and potassium. The application of dolomite limestone you used to adjust your soil’s pH will also help supply magnesium. Sulfur levels will usually take care of themselves unless you lawn has a history of high-nitrogen fertilization. Trace minerals including manganese, copper, boron, zinc and molybdenum will likewise take care of themselves, especially with applications of sea-derived fertilizers. Because these micronutrients are required in such minute amounts it actually can be harmful trying to supplement them directly. Best, of course, is a balanced compost.
Lawns Love Compost
For maximum growth and soil health, a lawn should be at least three percent organic material. Some extension services will test for organic material in your lawn’s soil, some will not. No matter how much organic material is already in your soil, adding compost using the guidelines below won’t harm it.
Before a new lawn is seeded, work three or more inches of compost into the soil. In cool climates, this is best done in the fall to avoid spring germination of weed seeds. Giving grass a chance to get started in the fall gives it a head start on the weeds they’ll be competing with once winter is over. Weeds are on a different schedule in warmer, Southern-state climates, often germinating late in the season. Spring plantings will be more effective in crowding them out. It is worth testing the pH of your compost, especially if you’ve made it yourself and included large amounts of highly alkaline components like wood ash or highly acidic ones like pine needles. You wouldn’t want to upset the balance you’ve worked so hard to achieve. Balance your compost’s pH rating as you did with your soil, using lime to counter acidity, sulfur to counter alkalinity.
Established lawns benefit greatly from a single yearly application of compost, even more greatly from two. Spreading compost on your lawn isn’t as easy as pushing your old chemical fertilizer spreader around. Depending on your lawn’s size, a wheel barrow and a shovel may be the best way to distribute compost around your yard, followed by a good raking (a push broom will also work) to distribute it more evenly. Though hard to find and troublesome to use effectively, a compost wheel or peat spreader can distribute compost across small yards though they can be difficult to push and need to be refilled often.
However you spread compost on top of an existing lawn, don’t apply too much. Compost should be spread no more than a half-inch deep. The idea is not to bury grass blades, smothering them and keeping them from sunlight. If that means less than a half-inch of compost, then reduce your application. You want grass blades exposed to oxygen and sunshine. Applying compost to problem areas will also help cure them.
Compost not only feeds the beneficial microbes in your soil, it introduces new microbes. Make sure the compost is well-finished and gives off only a rich, earth-like odor. Unfinished compost will not only smell but may rob your soil of oxygen. Best times to apply, according to Sachs, are in the spring before the grass begins to green and/or in the fall after the grass has gone dormant.
The Cutting Edge
Once your soil has reached its optimum pH with the right balance of macronutrients and your organic lawn is established, it’s easy enough to maintain if you’re making a yearly application of compost. Most of the additional nitrogen, phosphorous and potassium, and all the organic material and micronutrients you need to maintain a healthy population of beneficial microbes in your soil will come from something you’ll do anyway.
Mowing without a collection bag, allowing your clippings to fall back into the yard, will supply the nitrogen and other nutrients your lawn needs to stay healthy during the growing season. Estimates, again from Ohio State University Extension, suggest that grass clippings can supply at least 25% of your lawn’s nitrogen needs. That, coupled with a yearly application of compost, should be enough to keep it healthy and green. You can supplement this amount by running your mower over the lawn after the leaves have come down in the fall, adding even more organic material that will decompose over the winter while serving as a mulch for your grass and protecting your soil (it may take two mowings to reduce the leaves to compostable size).
Fears that leaving grass clipping on your lawn may lead to thatch are unfounded. Because grass clippings are composed mostly of water, they decompose quickly. Thatch consists of dead and compacted turf roots and nodes as well as other organic matter such as dead weed stems, twigs and whole leaves. These tightly bound materials provide safe haven for pests and disease while crowding out beneficial microbes and limiting their movement. Indeed, soil microbes are your best defense against thatch and will keep your soil friable and porous. They’ll help decompose dead roots and other organic material that could become compacted. Adding grass clippings to your lawn will only help prevent thatch by keeping your soil and your lawn viable.
This same process will help keep weeds from germinating and spreading as well as discouraging insect pests. William Dest, associate professor of turfgrass studies at the University of Connecticut, compared lawns that left grass clippings as opposed to those that didn’t. His study showed that lawns on which clipping were left had 45% less crabgrass, 66% less disease and 45% more earthworms. These lawns also showed greater resistance to weeds because of their 25% greater root mass. Watering was more effective with 60% more water reaching grass roots. Lawns that left grass clippings uncollected reduced their need for nitrogen fertilization by 50%.
Don’t let those figures encourage you to drop your mower’s height in an effort to add even more clippings to your yard. Grass needs to gather sunlight and conduct photosynthesis. The more surface it exposes to the sun, the better able it is to do this. Taller grass also conserves water by shading soil and helps crowd out weeds. The rule of thumb is to never cut more than a third from your grass blades. Generally, this means leaving 3-1/2 to 4 inches of blade. This will be enough to not discourage root growth while leaving behind small clippings that will decompose more quickly. Keeping your mower’s blade sharp will avoid rough cuts that allow grasses to loose moisture quickly and become vulnerable to disease.
Once you have a rich population of soil microbes working for you, caring for your organic lawn will be easier in all ways. But, just because your soil is well aerated and friable, because it’s retaining moisture, because strong root growth is discouraging lawn pests and thick, above-ground grass is crowding out weeds and all those grass clippings are adding nutrients back to your soil; all these benefits don’t mean that you’ll completely avoid problems. You may have to add modest amounts of nitrogen at the end of the growing season so your grass will have what it needs in the spring. You will still have to water, especially in times of less rainfall, just not as much. You will still have to bend down and pluck out the stray weed. But you’ll have a healthy, organic lawn thanks to healthy, organic soil. And you’ll have healthy organic soil thanks to your organic lawn.