Tom Hyden Carbon-Nitrogen Ratio Materials The Process

American farmer, teacher and philosopher Wendell Berry wrote: "If a healthy soil is full of death, it is also full of life: worms, fungi, microorganisms of all kinds ... Given only the health of the soil, nothing that dies is dead for very long."

Life, death, worms, fungi, decomposition — all are natural processes whereby soil is created and fertility is maintained. In many places, Iowa for example, soil was created to such an extent that the topsoil is 20 feet deep in some places. That is natural compost production.

The single most important growing practice that we can adopt is making compost and adding to our gardens. Here are the Top 10 Benefits of compost:

• Reduces soil compaction

• Makes soil easier to till

• Kills weed seeds

• Balances pH levels

• Makes soil dry more slowly

• Improves soil texture

• Feeds beneficial bacteria

• Holds plant nutrients

• Recycles wastes

• You can make it yourself

With a list like that, what are you waiting for?

All living things, whether humans or bacteria, need four things: an energy source, a protein source, moisture and air. For bacteria that are decomposers, energy comes from carbon and protein comes from nitrogen. To create a successful compost system, you must have the correct ratio of carbon to nitrogen. If you built a compost pile once and it smelled bad, you had too much nitrogen. If you raked all the leaves in the fall, piled them up and, two years later, nothing had happened, you had too much carbon.

The perfect carbon-nitrogen ratio is between 25:1 and 35:1, which means between 25 and 35 parts carbon to 1 part nitrogen. For example, the carbon-to-nitrogen ratio for dead leaves is 50:1; for kitchen waste, 12:1; sawdust, 400:1.

Most materials will not compost easily by themselves. We can solve that problem by blending kitchen waste with leaves or old hay with cow manure. There is one readily available material that has an ideal carbon/nitrogen ration: horse manure. I use large quantities of horse manure and have never had a batch fail to "cook." We'll pause here for a word of warning: Before you begin hauling horse manure into your backyard, warn your neighbors. Better yet, enlist your neighbors in a joint compost project. Well-made compost won't smell bad, but manure will smell like manure as it is decomposing.

In general, carbon materials are brown, dry and dead. Some readily available carbon materials are dead leaves, hay, straw, sawdust and newspaper. Nitrogen materials, on the other hand, can be described as green, fresh and still alive, such as green hay, kitchen waste, manures, weeds and grass clippings.

There are materials that should not be used in compost. Some plant materials are toxic or anti-bacterial such as pine needles, cedar, walnut, redwood and treated lumber. Animal by-products such as meat scraps, milk, cheese, or chicken carcasses are hard to compost and often putrefy. Cat litter should not be used. Also, old tomato and squash vines should not be composted because they are prone to be infected with a variety of viruses, bacterium and insect adults or larvae. Gather up the dead plants in the fall and burn them.

The process of composting is creating the perfect environment for bacterial growth. Let's assume that you have mixed materials until you have a carbon/nitrogen ratio of 30:1. You have watered the pile and it is full of air spaces. Now you wait for the bacteria to wake up and they wake up hungry. The only work that bacteria do is eating. They begin to gnaw on the carbon in the cells of the leaves and nosh on the nitrogen in the apple cores that you so kindly provided. At first, the mesophilic bacteria work at about 50 degrees and slack off at about 110 degrees. Their relatives, the thermophilic bacteria take over and raise the temperature as high as 160 degrees. Depending on the size of your pile, the temperature will stay high for several weeks and even a month later may still be over 100 degrees. After a month the pile should be turned over, watered again and allowed to re-heat. Continue this process until your compost looks like potting soil. In the spring apply it to your garden and stand back and watch everything grow.

Next time: composting methods.

Hyden began his gardening career at age 8 in order to win a Cub Scout badge. Since then, he has been a school teacher, served five years in the Peace Corps, survived earning a master's degree, and is still in search of the perfect tomato and rhubarb in the desert. He and his wife, Robyn Harrison, live on a farm between Luis Lopez and San Antonio, N.M.