PRAIRIE GARDENER: Fall leaves and garden debris make for excellent compost

When settlers moved into Dakota Territory back in the 1870s and '80s, they couldn't believe the organic matter content of the soil. Crops grew at rapid rates and produced yields that were astonishing. After more than a century of cultivation, soi...

Darrel Koehler
Darrel Koehler

When settlers moved into Dakota Territory back in the 1870s and '80s, they couldn't believe the organic matter content of the soil. Crops grew at rapid rates and produced yields that were astonishing. After more than a century of cultivation, soils have lost some of their organic material, but we can replace it with compost.

Gardeners who have used compost the first time can't believe the results. It isn't called ''gardener's gold" for nothing.


Years ago, barnyard manure, straw, corncobs and similar waste were all reincorporated into the soil to return some nutrient value, but primarily to maintain the soil's superior tilth. The compost pile or bin was a common farmstead sight in those days. The family vegetable garden, flower garden, trees, shrubs and lawn would receive benefits from application of composted or organic matter.

Now with leaves coming off the trees and frost-ravaged gardens in need of a good cleaning, we can all have our own compost operation. According to Ron Smith, NDSU extension horticulturist, proper composting is the gradual aerobic microbial decomposition of organic material. The finished product is humus when it is removed from the bin or pile is a dark, friable, odorless product similar to the organic material found in the soil.


The quickly available nutrient value in compost is generally low, but its major influence is on the improvement of physical conditions in the soil structure and a slow release of nutrients, especially nitrogen.

Adding properly aged compost to the soil will improve its water holding capacity and enrich the soil bacterial activity which, in turn, has a direct affect on the availability of some mineral salts to plants.

Basically, there are two acceptable systems for compost production: a simple, cool, low production method utilizing only dry organic matter, such as lawn clippings, leaves, corn husks, and a more rapid, sophisticated, high temperature production system, utilizing organic kitchen waste as well as yard and garden refuse.

Cool system

This is simply a pile of leaves grass clippings, leaves, egg shells and pea pods that will compost slowly into humus. Because the low temperature associated with this type of compost production, weed seeds and plant diseases aren't killed. Consequently, weeds that have gone to seed or diseased plants such as tomatoes should not be added to the pile.

This method takes four to six months to complete, so some nutrient leaching will take place. You can speed up the process by occasionally turning the pile and adding nitrogen fertilizer along with some water. It should reduce the composting time by half.

Hot system

The hot system accelerates the decomposition process, and in doing so it kills most of weed seeds and plant pathogens. Often the three-bin system is used. The first bin is for raw material, which would include household refuse, shredded leaves and garden refuse. The pile should be turned every two to three weeks. The next stage is to take the material from this bin and place it in the second where it is turned every three to four days. When it becomes humus it is transferred to the third bin. It should be ready for application to the garden at this point.


You can purchase bins at many garden centers and similar sources or you can construct your own. The bulletin, "Composting Practices," by Dr. Smith, is available at North Dakota county extension offices

If bad smells are noted from the compost pile, it usually means the anaerobic bacteria are more active than the aerobic bacteria, and that aerobic decomposition is slowing down. This is usually caused by excessive moisture in the bottom of the compost pile. The problem can be easily corrected by turning the pile.

In this high-temperature, bacterially active system, it is best to turn the composting material every three to four days. The decomposition will go faster in summer (as short at three to four weeks) and take more time in spring and fall. No measurable activity occurs during typical North Dakota winters.

Once the compost is no longer hot and is an odor-free, crumbling material, it is ready for garden use.

Smith said two alternatives of the hot production system exist. One involves using a plastic trash bag, where the bag is rolled every day. The other uses commercially available compost bins, which are described above. Both will yield a compost product in two to three weeks.

Composting benefits

Compost modifies temperature extremes in the soil, keeping it cooler in summer and warmer in winter.

Composted soil utilizes rainfall or irrigation water more efficiently, because less moisture is lost due to evaporation and runoff by permitting better absorption.


Composing adds a biological activity to the soil, which contributes to more efficient nutrient uptake. It also offers a buffering effect if you over-fertilize. The application of compost will also allow the soil to better hold plant nutrients for a longer period of time.

Koehler is the Herald's garden columnist. Send garden questions to him in care of the Grand Forks Herald, Box 6008, Grand Forks ND 58206-6008.

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