Leaf Raking Makes for Fewer Pests, Good Compost

Date: Nov. 24, 1997
Editor: D'Lyn Ford,  (505) 646-6528, dlford@nmsu.edu

LAS CRUCES -- Raking up fallen leaves not only improves your yard's appearance but also eliminates winter hiding places for insects and diseases.

"Raking up the leaves in your yard will reduce pest problems in your landscape next spring, and the leaves can be recycled in the garden as compost," said George Dickerson, horticulture specialist with New Mexico State University's Cooperative Extension Service. "Compost improves the structure of your soil and serves as a valuable source of nutrients."

Because leaves tend to mat in a compost pile, Dickerson recommends putting them through a shredder or running over them with a rotary mower. Turning the kids loose on a large pile of dry leaves is a fun way to achieve the same purpose.

Shredding also increases the surface area of the leaves, allowing microorganisms to break them down during composting.

"Leaves tend to be high in carbon, so it's important to add old grass clippings, food waste or livestock manure to the pile," Dickerson said. "These materials tend to be higher in nitrogen and will help the microorganisms break down the carbon. Throw in several shovels of soil in the mixing process to inoculate the pile with microorganisms to get the process started."

Because composting is a biological process, it's also important to add water to the pile, he said. Compost should have the consistency of a damp sponge. Adding too much water will force the air out of the pile, making compost smelly.

"Optimum composting conditions occur when the compost pile begins to heat up," Dickerson said. "Properly constructed piles can reach temperatures of 130 to 150 degrees Fahrenheit. This is hot enough to kill most weed seed, insects and disease pests in the pile. It's important to keep the pile turned with a garden fork at these temperatures to keep it cooking and make sure all the material heats up."

Compost can be made in a pile or bin. Bins should be well-ventilated to ensure air circulation. Dickerson recommended that the bin or pile be at least 3 feet high and 3 feet wide to create enough mass to insulate the pile from cold weather and to ensure that the compost heats up.

Under less than ideal conditions, however, the compost pile may not reach temperatures high enough to kill weed seeds or plant diseases.

"Don't worry, your compost will break down eventually," Dickerson said. "But it's important under these circumstances that the pile doesn't contain weed seed or plants that were infected with soilborne diseases. This could spread these pests in the garden next year."

Pet manures, fats or oils should never be added to the pile. he said. Vegetable peels and landscape wastes are ideal compost material.

For more information about composting, contact your county Extension office or the NMSU Bulletin office at (505) 646-3228. Ask for a copy of Guide H-110, "Backyard Composting." A composting video also can be checked out.