We have to eat to live. Without a regular supply of starch, protein and other complex nutrient we should soon die. Plants have a different arrangement. Plants - from the smallest seedlings to the largest trees - are factories which take in raw materials from the air, water and soil to build carbohydrates, proteins and fats. To do this they need a constant supply of raw materials and a source of energy - sunlight - to form roots, leaves, stems, flowers, fruits and seeds. Each part of the plant has a special job to do but its performance depends on the co-operation of every other parts.
In the last hundred years, great strides in the study of plant nutrition have been made. We now know that apart from carbon, hydrogen and oxygen, which plants get from air and soil water to manufacture their own starch and sugars, about a dozen nutrient or elements are also essential for plant growth.
PHOSPHORUS - Similar to nitrogen deficiency but leaf colour either dull bluish green with tints of purple instead of yellow or red, OR leaves dull bronze colored with purple or brown spots (leaf edges often brown, especially in potatoes).
POTASSIUM - If mild deficiency, stems thin; if severe, stems stunted or die; leaves usually dull bluish green, often yellow streaks between veins, followed by browning of tips and edges, and development of brown spots near edges; leaves rolled (begins at lower leaves); poor root growth; poor development of flowers and grain or fruit.
CALCIUM - Begins at upper leaves; leaves very distorted and curled at edges; edges appear ragged and leaves may have thin yellow bands or be brown, then die roots poorly developed.
MAGNESIUM - Leaves turn yellow (sometimes between veins, sometimes in spots or streaks), then turn brown and die (starting at bottom of plant); grain or fruits poorly developed.
MANGANESE - Similar to magnesium but starts at top of the plant.
SULFUR - Reduction of growth; curling down of leaves at tips; similar to nitrogen deficiency except that lower leaves are not lost.
BORON - Begins at upper leaves; leaves become light green (lighter at base, veins turn purple, leaves may have faint streaks and yellowing, then turn orange) and stop growing, root down at tip, with tissue breakdown at base, poor growth of tops and roots; flower buds drop off; no grain or fruit.
IRON - Severe yellowing of newer leaves (either spotted or total); more often visible in trees than yearly crops.
ZINC - Molted spots on leaves, first yellowish, then yellow or purple-red (appears late in summer, then leaves drop early), leaves become crinkled and small.
MOLYBDENUM - Similar to nitrogen deficiency, since molybdenum is necessary for nitrogen-fixing bacteria; leaves becoming yellow between veins, first on mature leaves, then to younger; young leaves may become severely twisted and eventually die.
NITROGEN in biological life is an electrolyte. As an electrolyte in the soil, nitrogen functions very much like a metal carrying an electrical charge. It is the element that ionises the water in the soil and make it possible for the minerals to get into the plant. Therefore, without nitrogen in the soil the electrical currents could not flow and the process of ionisation, by which plants are built, could not take place.
PHOSPHATE in the soil is the factor that determines the mineral content in any plant. The higher the water soluble phosphate the higher the mineral content. In order to get the maximum yield, the proper amount of phosphate is necessary. A great deal of phosphate used on farms today comes from Florida.
POTASH determines three basic things in a plant. It determines the thickness of the leaf and the thickness of the stem. The second thing it determines is the number of fruit sets on a plant and is the binder that holds the fruit to the stem. Thirdly, it determines the size of the fruit.
CALCIUM was once considered to be a secondary or minor nutrient for plants. However, we have learned in recent years based on research and its importance to the plant that it is now classed as a primary or major nutrient. By weight and by volume, plants need more calcium than all other plant foods put together. Calcium is the element that can increase the volume of a crop more than any other element.
pH of the soils varies however, most soils are between 4.5 and 8.0. pH is determined on a scale of 1.0 to 14.0 with 7.0 being neutral. A reading of 1.0 to 7.0 are acidic and the lower the reading away from 7.0 the more acidic the soil. Readings from 7.0 to 14.0 are the alkaline and the higher the readings from 7.0 are more alkaline. pH can be adjusted in the soil using calcium (lime) to raise it and the sulfur to lower it. Keep in mind that if the organic matter in the soil is good it will buffer the pH that might affect the plant.
Plants need water, in fact all the chemical reactions that take place in the plants require the presence of water. All movement of nutrients through the plant and the soil require water. Water also aids in giving the plant firmness. Too little water and the plant will wither, on the other hand too much water and the roots will be starved of oxygen and rot. Young plants need a bit more water to help build new root systems. Many also need more water when they set their flowers or when fruit and vegetables are maturing. Keep in mind that soils rich in organic matter hold moisture well, but release any excess to a deeper holding level in the subsoil structure for later use by the plant. If the rainfall is less than one (1) inch for week, additional watering will be required for most crops.
The traditional way to feed plants is to sprinkle a granular fertilizer containing all the major nutrient over the beds and borders and then on a soluble fertilizer at intervals.
It is advisable to apply fertilizer more frequently in lesser quantity.
~> Do not sprinkle fertilizer along seed drills.
Plants are much like people, they need nourishment for survival, growth and reproduction. The manufacture their food by a process known as photosynthesis. This process is made possible from elements in the air, water and soil. They get what they need from the air it breaths, inhaling carbon dioxide (CO2) and exhaling oxygen (O2). To get what it needs from the soil, it absorbs water, oxygen and certain nutrients, such as nitrogen (N), phosphorous (P2O5), potassium (K), magnesium (mg), sulfur (S) and calcium (Ca) and certain other chemicals known as trace elements.
Even though stems make some food, it is primarily in the leaves that food production takes place, from water (H2O) and nutrients brought up by the stems from the roots and what is taken in from the air (80% of its nitrogen requirements come from this source). On the underside of the leaves there are tiny pores called stomata (mouth) through which carbon dioxide (CO2) enters. This gas is combined with water (H2O) and nutrients by means of the green chlorophyll in the leaves. This process produces carbohydrates that nourish the plant.
Since so much of what plants need come from the soil, it is imperative to have good soil/ it is not just a matter of spreading fertilizers to improve fertility, the soil must have the proper balance of the other necessary elements. It is important for the soil to also have good structure. Most soils are composed of inorganic minerals, particles, air, water and organic matter -- matter that was once living plant or animal tissue. It is important to acknowledge the fact that soils vary greatly from one part of the country to another. Soil structure ranges from course gravel down to fine silt. In between we find loam to be the ideal type of soil. In most cases this textured allows air and water to move freely. At this point it is necessary to remember that air and water are of the utmost important to good plant growth. Not only do these lighter textured soils warm up faster in spring, they make it easier for the plant roots to penetrate as they grow. There is a negative side to these lighter soils. Water tends to drain more quickly, taking nutrients with it leaving the soil dry and infertile. Heavier soils such as clay leave little space among the particles for a good air water movement. These soils are often waterlogged and poorly drained. This condition can rob the plant roots of oxygen and cause them to rot. Toots find it harder to penetrate and these types of dense soils warm slower.
Particle size in the soil is not the only important factor of soil structure, organization of the particles also matter greatly. Ideally, soil particles are clustered together in groups and are not as distinguishable say as sand particles. Nor are particles so close together that they form a tight mass as does clay. The ideal soil will crumble much like homemade bread. Good soil structure is known to "crumb" or have good "tilth". This crumbling or tilth is caused by the high organic matter in the soil. A light, almost fluffy soil is referred to as being "friable".
Organic matter in the soil is merely dead, decayed plant and animal tissue. This matter is left above ground by animal excrement and their carcasses in combination with dead plants and fallen leaves. Below the surface worms and moles have also left their contribution with help of plant roots that have died and rotted. This decomposed matter is then called "humus". Humus contains sticky gums that bind the soil particles together into those all important clusters or crumbs. Not densely, however as with tightly packed clay, but with spaces through which water and air can pass.
Organic matter in the form of "humus" helps aerate the soil. It makes the soil more able to conduct water, retaining some for the plants to use, but letting the excess drain to a deeper holding level in the soil sub-structure.
In addition, organic matter contains important nutritional elements that the plants need. Soil microorganisms break down organic matter into basic elements, in forms that can readily be absorbed by the plant roots. Therefore, organic matter gives the soil a good structure and helps make it fertile at the same time.