Yard waste has been banned from public landfills in North Carolina since 1993. A beneficial, easy way to make use of yard waste is to turn it into compost. Typically, sources of compost include yard waste (for example, turfgrass clippings, fallen leaves, and wood chips) and animal manures. Composted materials may be incorporated into soil to improve conditions for plant growth.

Wood chips and grass clippings may be used, without composting, as mulch around the bases of trees and shrubbery or in landscaped areas. Clippings from grass that has been treated with any pesticide should not be used as mulch because they could damage plants. Proper mulch will help retain moisture in the soil and help prevent erosion of bare soil. Do not mix materials that have not been composted into the topsoil before seeding a lawn, and do not use fresh compost as a topdressing fertilizer for an established lawn. Fresh compost could kill grass and will tie up nitrogen in the soil.

Compost as Mulch and Fertilizer

Properly cured compost may be used as a mulch or as an excellent source of organic matter for a lawn, whether incorporated into the topsoil before seeding or applied as a topdressing on an established lawn. To incorporate before seeding, use a rototiller or mix with the topsoil before spreading. One cubic yard of compost will cover about 108 square feet when applied to a depth of 3 inches; 216 square feet at a depth of 2 inches; or 324 square feet at a depth of 1 inch. As a rule of thumb, spread compost no more than one-third the depth of the rototiller. For instance, a 1-inch layer of compost should be tilled to 3 inches deep. Two or more passes with the tiller will help ensure uniform distribution of compost and break up any large pieces of soil or compost.

To apply compost as a topdressing over a large area, use a rotary spreader if the compost materials will pass through the openings in the spreader. If the compost material is too large or irregular, spread the compost by raking out piles of compost placed evenly throughout the lawn. Apply no more compost than will cover half the height of the turfgrass. Applying a thick layer of compost that covers the turfgrass will block sunlight and decrease growth; it may also interfere with mowing.

Benefits of Compost in Soil

When used as a soil conditioner or in place of topsoil, properly cured compost is better than high-quality topsoil. Rocks and sticks are often screened out of compost, and many weed seeds are killed by the high temperatures of the composting process. The consistency of compost is often very uniform, so it may be handled more easily than less consistent topsoils. A well-cured compost is dark, crumbles in the hand, has uniform particles no larger than a half inch in diameter, and has a pleasant odor.

Compost offers many advantages over topsoil. It has:

• Higher nutrient content.

• Higher amounts of organic matter.

• Better nutrient- and water-holding capacity.

• Neutral reaction.

• Disease-control potential.

The nutrients held in organic compounds by dead plant matter are slowly made available as the organic matter decomposes. Once applied to the soil, properly cured compost releases these nutrients through additional microbial activity and decomposition. The complex organic compounds in the compost provide structure to sandy or heavy-clay soils.

In addition to providing nutrients, compost improves the ability of the soil to retain nutrients added through fertilization. The improved structure also increases water-holding ability in sandy soils and water infiltration in heavy-clay soils. High levels of organic matter increase microbial activity, which helps to decrease thatch levels, release nutrients held in the soil, and control certain pathogens that cause disease in turfgrasses.

Other Compost Sources

Yard waste is only one source for compost. It may, however, be the most readily available source. Another good source is animal manure. Before using sources from outside your own yard, find out all you can about pH level, salinity levels, nutrient value, heavy metal content, and stability or maturity. Content of animal waste can be analyzed via the NCDA&CS Agronomic Services Division. High levels of acidity or salinity can cause severe problems in your lawn. High levels of unwanted nutrients or heavy metals can be harmful to the lawn or to the lawn owner. An unstable compost will not perform on the lawn as a mature compost will, so further curing may be necessary before application to an established lawn.

Other Soil Conditioners

Other nonchemical products are available as soil conditioners. These products can be used to improve the soil’s physical or biological characteristics or both. Humate, diatomaceous earth, calcined clay, and greensand are examples of soil conditioners. (Products affecting primarily the chemical properties of the soil are considered as fertilizers in this publication.) Such products vary greatly by brand, and their effects have not all been evaluated scientifically. Before using soil conditioners, find out about their pH level, salinity level, nutrient value, heavy metal content, and organic stability. Also, note that some may contain chemical additives or may have been chemically altered so that they do not fit the definition of “organic” used here.

Rotary spreaders cover a wider area faster than drop spreaders, require less effort to push, and have better ground clearance. Drop spreaders have more uniform patterns, lower drift potential, and a more precise control of pattern edges than rotary spreaders. Drop spreaders are preferred for smaller, more contained areas of turf.

Calibrate the spreader under conditions similar to those in which it will actually be operated. Factor in ground speed, rate, pattern settings, operator, wind speed and direction, terrain, temperature, humidity, and product applied. Different spreaders, even from the same manufacturer, should be calibrated individually. Variations in characteristics of the impeller (paddle or spinner)—such as diameter, speed (gear ratio), concavity (flat or concave), height above ground, fin shape, angle, and surface—will affect the calibration.

Calibrate the spreader individually for different products. Characteristics of the product to be applied—including particle shape, size, uniformity, density, critical relative humidity (the level of humidity at which the particle becomes sticky), and surface friction—will affect distribution.

Different operators require individual calibrations. The walking speed, handle height, and pattern of travel are controlled by the operator.

Wind speed and direction, surface slope, temperature, and relative humidity affect distribution. When conditions interfere with applying the product in a uniform manner, it is a good idea to delay application.

(Note: All collection pans used to calibrate a spreader must be the same size. Square pans should be 1 to 2 square feet and 2 to 4 inches deep. To prevent material from bouncing out of the pans, place pads or baffles inside them.)

How to Calibrate a Rotary Spreader

1. Place collection pans in a line perpendicular to the travel direction of the spreader. Use at least 10 pans to cover the full width of the pattern. For large spreaders, 20 to 30 pans may be needed.

2. Make several passes in the same direction over the pans. Make sure the spreader is open before reaching the pans and remember to walk at the same speed each time.

3. Collect and weigh the material in each pan on an accurate scale.

4. A desirable pattern is one that places the highest amount of material in the center and evenly decreasing amounts toward each side of the pattern. Unlike a drop spreader, some overlap of the pattern will be required to achieve a uniform distribution of the material. Adjust the distance between spreader passes so that the material is thrown back as far as the wheel marks from the previous spreader pass. It is important that equal amounts of material be applied to the left and right side of the spreader. Skewing of the spreader to one side may be corrected by repositioning the pattern-adjustment control (if the spreader has one) or restricting the discharge ports.

5. The width of turf covered by each pass of the spreader is determined by determining the trays on the left and right that are equal to one-half of the amount in the center tray.

Use the weight of material collected from the pan in the center in the equation below:

\(Weight\ of\ material\ per\ 1,000\ sq\ ft\ =\ 1,000\ \times\frac{weight\ of\ material\ collected}{area\ of\ pan\ \times\ number\ of\ pans\ \times\ number\ of\ passes\ }\)

6. If the proper rate is not achieved, change the spreader setting or the number of passes. Repeat the process until the spreader is applying the material at the proper rate.

How to Calibrate a Drop Spreader

Pan Method

Push the spreader over a line of identical pans and collect and weigh the material. Measure the area of an individual pan and then use the following formula to determine the application rate:

\(Weight\ of\ material\ per\ 1,000\ sq\ ft\ =\ 1,000\ \times\frac{weight\ of\ material\ collected}{area\ of\ pan\ \times\ number\ of\ pans\ \times\ number\ of\ passes\ }\)

Sweep-and-Weigh Method

Push the spreader over a clean, smooth surface of a known distance and collect the material. Determine the application rate through the following formula:

\(Weight\ of\ material\ per\ 1,000\ sq\ ft\ =\ 1,000\ \times\frac{weight\ of\ material\ collected}{spreader\ width\ \times\ distance}\ \)

Catch-Pan Method

Attach a catch pan to the bottom of the drop spreader. Establish a known distance. Push the spreader over the known distance, opening the hopper at the starting point and closing at the end point. Determine the application rate with the following formula:

\(Weight\ of\ material\ per\ 1,000\ sq\ ft\ =\ 1,000\ \times\frac{weight\ of\ material\ collected}{spreader\ width\ \times\ distance}\)

Whatever method is used, make enough passes or travel enough distance so that enough material is collected to be weighed accurately. Change the opening in the spreader to adjust the rate. Repeat the calibration until the correct rate is achieved.

1. Make sure the lever is closed before filling the hopper of the spreader.

2. Make sure the screen filter is in place to prevent clogging.

3. Push the spreader; do not pull.

4. Start walking and reach the calibrated speed before opening the lever to release the material; close the lever before slowing, turning, or stopping.

5. Hold the handle at the same height used in calibration. The impeller should be level.

6. Walk in straight lines. Use reference points such as spreader wheel marks or footprints.

7. Do not spread while turning. Generally, only one wheel drives the impeller. Continuing to spread while turning will cause the impeller to change speed, altering the distribution pattern.

8. Keep material dry to prevent caking and clogging of the spreader ports.

1. Wash the spreader after each day’s use to avoid buildup around ports and on the impeller. Water is adequate for cleaning water-soluble products. Dry completely to prevent rusting.

2. Store the spreader empty in a cool, dry place.

3. Lubricate as specified by the owner’s manual.

The key to successful organic lawn care is to strive to prevent problems rather than treating them after they appear. For success with your organic lawn, choose a sunny, well-drained site, and protect and prepare the soil as recommended. Select a turfgrass that will grow well in your area and wear well for the uses intended, and then water and fertilize appropriately, mow on schedule, and inspect the lawn frequently to spot any problems early.

It is important to recognize that just because a product is labeled as organic or comes from a natural source does not mean that it poses no threat to the environment or to people, pets, and wildlife. To prevent water pollution from organic fertilizers, follow recommended rates for application and sweep fertilizers off paved surfaces. Nitrogen and nutrients from any source, organic or otherwise, should be kept out of streams and other nearby waterways.

Some organic pesticides are very toxic and should be stored in a locked or secure place. If you use such products, always read and follow product labels. The “organic” products on the market change frequently. No brand names are listed in this publication because new products become available each year and others are taken off the market or are not available in every location.

Consult your local N.C. Cooperative Extension center for current information.