September 10, 2016

1 - Composting is a good gardening practice and can be enhanced by a knowledge of a few composting principles.

Yard and Garden September 10, 2016

Q.

I have decided that it is foolish to throw away leaves from my trees and other garden wastes. I want to learn to compost these things and use the compost to improve my garden. Do I have time to start composting now and add leaves from the trees this fall to make compost that I can use in my garden next spring?

A.

Yes, you have time. You may not see everything completely decomposed, but there will be some compost formed, even through the winter.

There are several factors that can help speed the decomposition of lawn and garden wastes to maximize the compost that is produced. Important factors are moisture and aeration. The fungi, bacteria, and other organisms that decompose the waste need moisture, but they also need oxygen (in typical garden composting). The compost should not be soggy, but about as moist as a squeezed out kitchen sponge or wash cloth.

You should turn your compost frequently to avoid excessive decomposition and development of soggy conditions in the center and bottom of the compost. This moves the most decomposed materials to the outside, mixes it with material that has not yet decomposed (speeding the decomposition of this material), and mixes air (oxygen) into the center and bottom of the compost pile.

Proper particle size will help. Very small particles hold water and provide much surface area per particle for the fungi and bacteria to feed upon, but very finely ground materials will become soggy quickly. Some coarser material mixed in will help maintain pore space filled with air close to all particles. This will allow water to drain and avoid development of soggy conditions. These coarser particles will decompose more slowly, but they may be removed by screening the compost before using. Some of the coarser material can be mixed into your garden soil to help provide aeration in the soil, especially if your soil contains much clay.

A proper balance of carbon containing materials and nitrogen materials is necessary for optimum composting, but composting will still happen, though more slowly if the carbon to nitrogen ration is not optimal. Materials high in carbon to provide food (carbohydrates) for microorganisms include dried brown leaves, ground twigs, larger wood chips (good for aeration), and other such "brown" materials. High nitrogen materials include fresh lawn clippings, kitchen wastes, freshly fallen leaves, manure, and similar substances. The optimum ratio is 30 parts carbon materials to 1 part nitrogen materials. The closer you are to achieving this ration, the faster the garden wastes will decompose and the higher the temperature that will be generated in the compost to kill disease organisms, weed seeds, and insect eggs. Proper aeration works hand in hand with the carbon to nitrogen ration to provide speedy and hot composting. Any material that reaches 130 to 160 degrees will have many diseases, seeds, and insect eggs killed.

I commend you for deciding to compost. Garden wastes are a problem in landfills, causing them to fill rapidly, but properly made compost is a great addition to your garden to help the soil hold moisture and nutrients. The compost will also provide slowly available nutrients to your garden crops. A soil test is still recommended to maximize garden production, but the compost will help maximize plant use of garden nutrients that you apply.

There is much more information available to help you learn composting at your local NMSU County Cooperative Extension Service office. If you live in the Albuquerque area you can apply to attend the 2016 Master Composter training which begins in October. You can find information regarding this class online at NM Composters. Do not delay in registering in case the training classes fill up. You will learn that there is much more to composting than what I can relay in this garden article.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!