AgriLIFE Extension -Denton County

  306 N. Loop 288, Suite 222

 Denton, Texas 76209-4887

February 28, 2008

TURN YARD WASTE INTO COMPOST

 Contact:  John N. Cooper, County Extension Agent-Horticulture, 940.349.2883

  e-mail: jn-cooper@tamu.edu

          When plants die the minerals locked inside their tissues are returned to the soil through decomposition by microbes and other soil organisms.  Although most plant minerals come from the mineral component of the soil, the organic matter (O.M.) fraction can make a significant contribution.  Every home landscape produces yard waste such as pruned wood, fallen leaves, and grass clippings that can be recycled and reused to promote plant health.

          When people become involved in the plant decomposition process we call it composting, which, if done correctly, speeds the process.  The finished product, compost, makes a rich top-dress fertilizer/soil amendment.  Just as minerals are added to the soil by the use of synthetic fertilizers, compost can also be used to supplement the natural release of minerals from the soil.

          Spread a one-quarter inch layer of compost on lawns one-quarter inch deep two or three times a year.  Till one or two inches into the top six inches of soil for vegetable and flower beds before planting each new crop.  Top-dress established groundcover and shrubbery beds with one or two inches of compost once or twice a year.  For new woody ornamental landscape beds, till one or two inches of compost into the top 10-12 inches of soil prior to planting.  To make a nice potting soil, mix equal parts compost and clean sharp sand.

          There are five basic ingredients managed during the composting process.  The primary ingredient is the O.M., which is the source of the carbon used by microbes for energy.  Microbes also need available nitrogen, oxygen, and water.  Finally, you need microbes.  The objective is to manipulate these ingredients to create optimum conditions for the microbes to work efficiently.

          To start a compost pile you need to chip, shred, or chop the O.M. into small pieces to expose as much surface area to the microbes as possible.  Spread a six-inch layer of prepared O.M. on the ground.  Add one-inch of soil, nitrogen if needed, and mix together while adding water as needed to moisten the pile.  The moisture content should be that of a well-wrung sponge.  Just a little water should come out when squeezed.  The soil is your source of microbes.  If there is one mistake people make it is not getting the O.M. “dirty” enough.  Don’t get skimpy with the dirt.  Repeat the above process, mixing each layer as you build the pile.

          Depending on the source of O.M. you may need to add nitrogen.  Microbes need a ratio of carbon to nitrogen of 25:1 to 40:1 for optimum performance.  Fresh lawn clippings have a C:N ratio of 20:1 so they actually need more carbon which can be supplied by oak leaves which have a 50:1 ratio.  Mixing equal parts lawn clippings and oak leaves, will give you the right C:N ratio.

          All O.M. materials have different C:N ratios but determining how much nitrogen to use is not a problem.  It just so happens that if you add one pound of actual nitrogen per 50 pounds of O.M. dry weight regardless of whether they are oak leaves with a 50:1 ratio, or sawdust with one of the highest C:N ratios at 500:1 you will still have a C:N ratio in the desired range of 25:1 to 40:1.  If you can estimate the weight of 50 pounds of dry O.M. and can calculate fertilizer rates, you will have it.  Ammonium sulphate has 21% nitrogen (21-0-0) so you have to add five pounds per 50 pounds of dry O.M.  Cotton seed meal has 7% nitrogen so you need to add 14 pounds.  Simply adjust the application rate according to the nitrogen content of the fertilizer you use.

          Once you mix and water the pile the composting process starts.  You would like to maintain a temperature between 85 and 115 degrees F.  It will spike to 145-165 for a few hours or days if the pile is really “green”, i.e., the C:N ratio is at the low end but will soon come back down to a more moderate temperature.  Turn the pile once a week to aerate and increase oxygen, and add water to maintain the proper moisture content.  If the pile smells like ammonia add brown (woody) material to re-balance the C:N ratio.  If the pile smells like rotten eggs, it doesn’t have enough oxygen, so turn the pile to aerate it and/or mix in dry matter if it appears too wet.

          The process is finished when the compost is dark and crumbly with a rich earthy smell.  Use the compost when it is ready.  If the process is allowed to continue, the pile will eventually vaporize into carbon dioxide, water, and heat.  Wear a dust mask when working with compost to reduce mold spore inhalation.  Never compost pet wastes if you plan to use it in vegetable gardens.  Cover kitchen scraps to reduce files, animals, and odors.  Do not add kitchen scraps of animal origin.  Cover pile when raining to prevent cooling and excess moisture.  Compost wood ashes but not charcoal or coal ashes.  Avoid using materials treated with pesticides.

          Compost bins are not required for composting.  Composting is a natural process that can easily be accomplished with a simple pile.  However, bins can be helpful in retaining core heat, regulating moisture, reducing space requirements, reducing odors, and excluding animals.                                                                         -30-

The information given herein is for educational purposes only.  Reference to commercial products or trade names is made with understanding that no discrimination is intended and no endorsement by AgriLife Extension is implied.

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Extension programs serve people of all ages regardless of socioeconomic level, race, color, sex, religion, disability or national origin. The Texas A&M University System U. S. Department of Agriculture, and the County Commissioners Courts of Texas Cooperating.