7/21/2007

Countryside & Small Stock Journal

By Elizabeth Miller

Chemical fertilizers are quick-acting, short-term plant boosts and are responsible for: 1) deterioration of soil friability, creating hardpan soil; 2) destruction of beneficial soil life, including earthworms; 3) altering vitamin and protein content of certain crops; 4) making certain crops more vulnerable to diseases; and 5) preventing plants from absorbing some needed minerals.

The soil must be regarded as a living organism. An acid fertilizer--because of its acids--dissolves the cementing material, made up of the dead bodies of soil organisms, which holds the rock particles together in the form of soil crumbs. This compact surface layer of rock particles encourages rainwater to run off rather than enter the soil.

For example: A highly soluble fertilizer, such as 5-10-5, goes into solution in the soil water rapidly so that much of it may be leached away (into our ground water) without benefiting the plants at all. This chemical causes the soil to assume a cement-like hardness. When present in large concentrations, they percolate into the subsoil where they interact with the clay to form impervious layers of precipitates called hardpan.

Many artificial chemical fertilizers contain acids, such as sulfuric and hydrochloric, which will increase the acidity of the soil. Changes in the soil acidity (pH) are accompanied by the changes in the kinds of organisms which can live in the soil. For this reason, the artificial fertilizer people tell their customers to increase the organic matter content of their soil and to use lime, offsetting the deleterious effects of these acids.

There are several ways by which artificial fertilizers reduce aeration of soils. Earthworms, whose numerous borings made the soil more porous, are killed. The acid fertilizers will also destroy the cementing material which binds rock particles together in "crumbs." Chemical fertilizers rob plants of some natural immunity by killing off the microorganisms in the soil. Many plant diseases have already been considerably checked when antibiotic producing bacteria or fungi thrived around the roots. When plaints are supplied with much, nitrogen (N) and only a medium amount of phosphate (P), plants will most easily contract mosaic infections. Host resistance is obtained if there is a small amount of nitrogen (N) and a large supply of phosphate (P). Fungus and bacterial diseases have been related to high nitrogen fertilization, and lack of trace elements.

Plants grown with artificial chemical fertilizers tend to have less nutrient value than organically grown plants. For example, several tests have found that by supplying citrus fruits with a large amount of soluble nitrogen will lower the vitamin C content of oranges. It has also been found that these fertilizers that provide soluble nitrogen will lower the capacity of corn to produce a high protein content.

Probably the most regularly observed deficiency in plants doped continually with chemical fertilizers are deficiencies in trace minerals. To explain this principle will mean delving into a little physics and chemistry, but you will then easily see the unbalanced nutrition created in chemical fertilized plants Note: The colloidal humus particles are the convoys that transfer most of the minerals from the soil solution to the root hairs. Each humus particle is negatively charged and will, attract the positive elements, such as potassium (K), sodium, calcium, magnesium, manganese, aluminum, boron, iron, copper and other metals. When sodium nitrate is dumped into the soil year after year in large doses, a radical change takes place on the humus particles.

The very numerous sodium ions (atomic particles) will eventually crowd out the other ions, making them practically unavailable for plant use. The humus becomes coated with sodium, glutting the root hairs with the excess. Finally, the plant is unable to pick up the minerals that it really needs.

So, with chemical fertilizers, in short, you have short-time results, and long-term damage to the soil, ground water and to our health.

Nutrient                                                      Role

Nitrogen (N)           Formation of chlorophyll, amino acids, protein    

Potassium (P)         Water transfer, stomata opening, winter hardiness, disease resistance    

Phosphorus (K)       Flower & fruit formation & maturity, cell division, root growth, energy transfer, membrane integrity    

Calcium (Ca)          Part of cell wall structure; membrane integrity; stem strength    

Magnesium (M)      Part of chlorophyll; essential for photosynthesis    

Sulfur (S)                Constituent of several amino acids    

Iron (Fe)                  Synthesis of chlorophyll; electron transport    

Manganese (Mn)     Catalyst involved in chlorophyll formation    

Boron (B)                Regulates carbohydrate metabolism; essential for protein synthesis    

Zinc (Zn)                Regulates plant growth; chlorophyll synthesis & carbohydrate formation    

Copper (Cu)            Protein & carbohydrate metabolism; catalyst for enzymes; synthesis & stability of chlorophyll & other pigments    

Molybdenum (Mo) Nitrogen fixation 

Nutrient Signs of Deficiency

Nitrogen (N)           Pale green or yellowish lower leaves, slow growth  

Potassium (P)         Older leaf edges turn yellow or brown, leave may be chlorotic and curl, may have necrotic spots    

Phosphorus (K)       Stunted, very dark green leaves; purplish to reddish coloration of veins, leaves or stems; late flowering & maturing of fruit    

Calcium (Ca)           Deformed or undeveloped terminal buds & root tips; blossom end rot on tomatoes & peppers    

Magnesium (M)       Mottling of older leaves; interveinal chlorosis 

Sulfur (S)                 Light green color of whole plant; chlorotic younger leaves    

Iron (Fe)                  Interveinal chlorosis of upper leaves leading to total bleaching; new leaves may be yellowish white    

Manganese(Mn)      Interveinal chlorosis, may be followed by necrotic spots; frequently occurs on middle leaves first    

Boron (B)                Dieback of shoots or growing points; thickened, wilted or curled leaves; distorted fruit; hollow root vegetables    

Zinc (Zn)                Short internodes; leaves appear rosetted; misshapen leaf blades; small leaves with interveinal chlorosis; abnormal root growth    

Copper (Cu)           Bluish-green appearance; plants wilt, young leaves die tip first, resembling frost injury; summer dieback of terminal shoots of fruit trees; affects flowering & fruit formation    

Molybdenum (Mo)  Yellowish or pale green leaves; deformed, mottled or cupped leaves    

Adapted from Fertilizing Garden and Landscape Plants and Lawns.  North Central Regional Publication No 356, August 1989.