Early civilizations in Greece, Rome and Israel recognized crops grew better when soil was supplemented with animal blood or manure. Soil fertility is naturally regenerated by the decay and decomposition of dead plants. Soil must provide the vast number of nutrients plants absorb through their roots. Plant physiologists therefore claim man must feed the soil not the plant. Soil is more than mud on my boots; soil is a dynamic living environment of bacteria, fungi, worms and beetles. A handful of dirt contains more bacteria than all the people on earth. Microorganisms feed on the starches in dead plant material falling on the ground in forests and fields. Microorganism metabolism converts dead plant protein into nitrogen-containing molecules that can be absorbed by plant roots so plants can produce new proteins, vitamins and other chemical molecules beneficial to the plant and man. At the same time, soil must contain some non-plant material like clay and sand so a plant can anchor its roots to stand erect.
It is obvious plants grow in soil. Through photosynthesis green plants produce carbohydrates by reacting water with carbon dioxide in the air using energy from sunlight. All other building blocks to make proteins and nutrients known to come from plants must be obtained through the roots. Plants cannot eat soil, but plants absorb nutrients like iron, calcium and sodium as well as nitrates to make protein. Scientists know plants produce large quantities of protein because vegetarians, who eat primarily plants, and cows, which eat only plant material, obtain enough protein to grow healthy muscular bodies just as meat consumers do.
Today, modern composting is a mechanism to speed up the natural process of plant decay and decomposition to produce humus or fertile soil. Think of humus as a fertilizer which in addition provides an environment conducive to healthy root function. Humus is a dark, earthy smelling, sticky vital substance that makes plants flourish. Home-made compost has dramatic physiological advantages for plants that fertilizer lacks because humus is a loose granular material consisting of aggregates of minute clumps held together by a gel produced by bacteria. Also, air and water trapped between aggregates becomes available for root absorption. Aggregates stick to each other retarding soil erosion during heavy rain. Humus produces chemicals which facilitate absorption of nutrients and macromolecules needed for growth.
The author retrieves humus, decayed and decomposed plant material, from his compost pile this week.
Photo by Beverly Ungerer
Simply, modern composting is done in the backyard with little expense but requires time and attention. My personal compost pile started two years ago inside a commercially purchased box kit of recycled black plastic panels 2-by-2-by-3 feet with a lid. To this container set over a few inches of hay I added 2-3 inches of leaves, a sprinkling of grass clippings, cantaloupe rinds, banana peels, spoiled left over plain pasta and kitchen vegetable scraps. On top of this, a half-inch of soil from my garden which harbors the microorganisms, the key agent in the composting, was added which started the decay and decomposition process. While soil was the key ingredient, animal manure could substitute as the activator. My compost, gathered from a sliding door at the bottom of the plastic compost box, was ready to add to transplanted vegetables or planted seeds after one year. While researching composting, two sources recommended adding human urine to the compost because urine contains urea, a rich nitrogen source. Because of my own ignorance, urine was omitted from my compost previously. I may experiment with this source of nitrogen in the future. Does compost really help? This summer I will plant some tomatoes with compost and some without then evaluate flavor and size at harvest.
I found two helpful books at local libraries describing how to construct and feed a compost pile, "The Rodale Book of Composting" and "Let it Rot-Gardener's Guide to Composting." Put your kitchen, refrigerator and yard wastes to good use this year and start a compost pile.