Mixed with soil, compost increases organic matter, improves properties and supplies nutrients

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By Staff Brunswick Beacon

Our waste disposal sites are filling up and landfills across the nation are being closed at an alarming rate.

At least 20 percent of the solid waste placed in landfills consists of yard and garden wastes such as leaves and grass clippings. One step we can take toward solving our waste disposal problems is to make compost out of our lawn and garden wastes.

When mixed with soil, compost increases organic matter content, improves physical properties of soil and supplies essential nutrients, enhancing soil’s ability to support plant growth. Compost can also be applied to the soil surface to conserve moisture, control weeds, reduce erosion and keep soil from gaining or losing heat too rapidly.

When materials such as leaves and grass clippings are composted, a microbial process converts them to a more usable organic material. Adding these materials directly into soil without first composting them will have the microbes that work to decompose the leaves and grass clippings competing with plant’s roots for soil nitrogen.

Decomposition of organic material in a compost pile depends on maintaining the activity of decomposer microbes. Efficient decomposition occurs when aeration and moisture are adequate, when the particles of waste material are small, and when the proper amounts of fertilizer and lime are added.


Microbes require oxygen to decompose organic wastes efficiently. Mixing the pile once or twice a month will provide the necessary oxygen and significantly hasten the composting process. A well-mixed compost pile reaches higher temperatures that help destroy weed seeds and disease-causing organisms.


Adequate moisture is essential for microbial activity. The pile must be watered periodically to maintain a steady decomposition rate. The pile should be watered enough so it is damp but does not remain soggy. Compost correctly watered will produce a few drops of water when it is squeezed. If no water can be squeezed out, the pile is too dry and if water gushes out, the pile is too wet.

Particle Size

The smaller the organic waste, the faster compost will be ready for use. Materials can be shredded before they are added to the pile. A low-cost method of reducing the size of fallen tree leaves is to mow the lawn before raking it or to run the lawnmower over the leaf pile after raking.

Fertilizer and Lime

Microbial activity is affected by the ratio of carbon to nitrogen in the organic waste. A shortage of nitrogen slows the composting process considerably. Grass clippings are generally high in nitrogen, and when mixed properly with leaves, they speed decomposition. Although adding lime to the compost pile may hasten the decomposition, the loss of nitrogen from the pile due to the adding of the lime often offsets the benefits. Lime is not necessary for the degradation of most yard wastes.

Materials for Composting

Many organic materials are suitable for composting. Yard wastes such as leaves, grass clippings, straw and non-woody plant trimmings can be composted. Grass clippings can be composted but if allowed to remain on the lawn, they will decay and release nutrients, reducing the need for fertilizer.

Such kitchen wastes as vegetable scraps, coffee grounds and eggshells may also be added. Ordinary black and white newspapers can be composted; however, the nitrogen content is low, slowing the decomposition process.

Other organic materials that can be used to add nutrients to your compost pile includes: fruit and vegetable table scraps, refuse from your flower garden, hay and straw.

Materials to Avoid in a Compost Pile

Animal products may attract rodents and create an odor. Citrus rinds, corncobs, stalks and husks, palm fronds, and walnut, pecan and almond shells break down very slowly and should be avoided unless they are shredded.

Charcoal also resists decay and will not decompose in most compost piles. Coal ashes should not be added because they contain levels of sulfur and iron that may be toxic to plants. Also, avoid plants that have been treated with pesticides or herbicides.

Just imagine, if every household in the United States composted at least some of their refuse, we would need fewer landfills and not have to use so much fertilizer on our plants. Just think about that!

Soil sample kits are now available at Lowe’s Home Improvement and Rosewood Nursery in Shallotte—at no charge.

Send your gardening questions or comments to: Brunswick County Master Gardener Column, P.O. Box 109, Bolivia, NC 28422, or call 253-2610. Enclose a self-addressed stamped envelope if requesting information or a reply. Answers may be printed in this column.