A garden soil well supplied with organic matter and minerals will produce a good yield of vegetables, high in quality, flavor and nutritional value. The same is true with flowers and shrubs. The organic content of the soil must be maintained at a high level in order to use fertilizers to their best advantage.
Adding some form of organic matter to the soil each year is just good gardening practice. Most gardeners think animal manure as the source of organic matter, however any composted plant materials such as compost, leaves, cotton burrs, vegetable leftovers, grass clippings and straw will do. It just has to be something that is decomposing. Composted materials can be spread on, mixed in, or used as mulch around growing crops. Mixing it into the soil will speed decomposing.
Many people ask if it is possible and practical to substitute organic matter for synthetic fertilizers. It may be possible on some soils, but in Southwest Oklahoma, usually not. Our soils produce best when they are given both organic matter and synthetic fertilizers.
Synthetic fertilizers are those fertilizers produced from either ammonium nitrate or urea, diammonium or monoammonium phosphate and concentrated superphosphate and muriate of potash. Organic fertilizers are by-products from livestock, fish, poultry industries and plant residue. As far as plants are concern, either fertilizer will work because they can’t tell the different.
Although the percent of nutrients found in organic matter are lower than what is found in synthetic fertilizers, they do provide some nutrients, especially nitrogen, to the plant. Organic matter also releases the nutrients already in the soil by turning them into soluble compounds that can be absorbed by the roots of the plants.
All soils, even those never cultivated, differ widely in their content of plant nutrients. The elements most frequently deficient include those normally present in fertilizers-nitrogen, phosphorous and potassium. Soils lose these nutrients through, plant growth, leaching and harvesting of plants.
Deficiency of plant nutrients in soil must be corrected if the soil is to produce adequately. Fertilizers, animal byproducts and manure are added for this reason and to increase plant growth on soils fairly well supplied with essential nutrients.
In nature, animal and vegetable matter decomposes to form humus-a dark brown or black substance. Humus is extremely important to the successful growth of plants of all kinds because it promotes a more favorable soil structure. Humus increases the water holding capacity of the soil, lessons erosion, decreases the loss of valuable minerals by leaching, and makes the soil easier to cultivate.
For good growth, the plants must have space in the soil to get air, room to grow, and adequate water, sunlight and mineral nutrients. Air and root space and water available to plants depend largely on the soil structure. This in turn is closely related to the organic matter in the soil and a suitable distribution of mineral particles of different sizes.
Adding organic matter to the soil can make a heavy soil lighter, more crumbly and easier to till. This is especially important in areas where the soil is high in clay. In soils that are more sand, organic matter holds the soil particles together, increasing their water holding capacity. Adding organic matter over several years will eliminate clay soils crusting over after a heavy rain.
The addition of organic matter to the soil does not reduce infestation of weeds, diminish plant diseases, nor protect plants from insect attacks. Nor does it have any marked influence on the vitamin content of crops grown in the soil. It does help keep the plant healthy to help resist the threat from insect, diseases and weed competition.