Plants Must Have A Complete Meal: Dealing With NPK

After discontent, then what? Hopefully, the customer exhibits some patience and the contractor has the desire to learn how to avoid that situation again.

Turf health and appearance relies on more than just the presence of adequate (or excess) nitrogen, which means the importance of micronutrients in a total and complex fertilizer program deserve attention, too.

NITROGEN (N). Nitrogen is the single most important nutrient that determines plant growth. This is due to its effect on stimulating plant growth hormones. Too much nitrogen will, however, increase disease incidence in plants. Two to three applications per year (at lower amounts) is usually preferable to larger amounts for a single application. Most fertilizer contains significant amounts of nitrogen.

PHOSPHATE (P). Phosphate is the nutrient that promotes "energy" inside of the plant. Over many years of fertilizer use, phosphate levels in the soil will be adequate. Good root health depends on adequate phosphate.

POTASSIUM (K). Potassium has many functions inside of a plant. One of the main functions is the regulation of cellular pH. This controls the digestion system of the plant.

N-P-K. These percent of these three nutrients in a fertilizer is represented by the numbers prominently displayed on the front of most fertilizer bags. Very seldom are they insufficient when plant food is regularly used. They are the meat, potatoes, and bread of the plant’s diet. They are referred to as major nutrients.

What about the milk, salad, fiber and vitamins of a plants diet? They are called micronutrients. Although they are used in small amounts, they are nevertheless necessary to the health of the plants. Following is the description of micronutrients.

THE ESSENTIAL ELEMENTS. There are 16 essential elements needed in a complete and total nutrient program to produce any crop. Carbon, hydrogen, oxygen and some nitrogen come from air and water. Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, zinc, boron, manganese, copper, iron, molybdenum and chlorine all come from soil and fertilizer applications.

It’s important to note that all of the aforementioned nutrients are important throughout the growing season.

Zinc - Zinc deficiency is the most common of the micronutrient deficiencies in the United States. It occurs in many crops and in many soils. Zinc deficiency is one of the easiest to diagnose - either visually or by soil or tissue testing - and to correct.

Certain soils are naturally low in total and available zinc, such as calcareous soils (pH 7.0 or above), acid leached soils, course sands, low organic (muck) soils and over-limed soils.

Excess phosphorus can induce zinc deficiencies, whether or not the interaction between zinc and phosphate occurs in the soil external to the plant or in the metabolic process within the plant. High phosphate applications or retention restrict zinc uptake. Then zinc will combine with soluble phosphates to form zinc phosphates, which cannot readily be dissolved. Iron and manganese, either in excess or deficiency, may be contributing factors in zinc deficiencies.

Zinc as a plant nutrient is important as a growth hormone and in seed and grain formation. It is particularly important in the maturation date of plants, in the height of plants and in protein synthesis.

Iron - The most important functions of iron in a plant are to promote formation of chlorophyll, the green pigment of the plant that functions in photosynthesis or starch production. Chlorophyll is the enzyme mechanism which operates the respiratory system of living cells. Iron is not readily translocated from old to new leaves, so a constantly available source is needed during the entire growing season.

High soil pH and the presence of free calcium carbonate (lime) induce iron chlorosis - even though high iron levels may be present in the plant.

Iron is found in abundance in most soils, but mostly in a form that is unavailable to the plant. This deficiency of available iron adversely affects plant growth.

Low soil temperatures can retard the growth rate of the plant’s root system and restricts the uptake of iron. As a rule, iron deficiencies in the field tend to diminish as temperatures increase and soil moisture decreases. Improved aeration encourages greater microbiological activity with greater root growth and exposure to soil iron.

Generally, a foliar application of iron is better than a soil application since it is not necessary to get involved with the soil’s chemistry or tie-up problems of iron with phosphate, magnesium and others.

Magnesium - Magnesium participates in the activity of enzymes, assists in the translocation of phosphorus in the plant and is found mostly in the chlorophyll-bearing tissues of a plant.

Adequate supplies of magnesium are governed not only by the absolute level of magnesium but also by the calcium:magnesium ratio. A large excess of calcium relative to magnesium may induce a magnesium deficiency. When magnesium is dissolved in the soil solution, it is absorbed through the root system by diffusion or ionic exchange. The competition from nitrogen, calcium and, particularly from potassium, interferes with the uptake and absorption of magnesium.

The rapid uptake of nitrogen fertilizers, when greater in ratio than the available magnesium, causes a deficiency. Just as in other non-mobile nutrients, the critical use period of magnesium is within the first 40 days of growth.

Manganese - Manganese is the predominant metal iron in the metabolism of organic acids. In higher plants, manganese activates the reduction of nitrate and hydroxylamine to ammonia. It is part of the important enzymes involved in respiration and protein synthesis, and it generally serves as an activator for a variety of enzyme reactions, such as oxidation, reduction, hydrolysis and group transfer.

Manganese has particular interest as it relates to photosynthesis. It may have a direct or indirect influence on chloroplast - the location of the conversion of sunlight energy to chemical energy.

Manganese deficiencies occur in sands, peats and muck, alkaline (pH of 6.5 or above) and particularly in calcarious over-limed soils, and well as soils with low organic matter.

Copper - Copper is required in small amounts in plant tissue for normal growth. The only other known essential element required in a lower amount by plants is molybdenum.

Copper’s function in plant growth cannot be replaced by any other element, as copper is an enzyme activator and becomes a component of certain enzymes that function in respiration and in photosynthesis. Copper itself is not a component part of chlorophyll; however, it is part of the enzyme system that becomes chlorophyll.

Sulfur - Sulfur should exist in one part for every 10 to 12 parts of nitrogen. Without sulfur, the plant cannot use its nitrogen - 1 to 12 is about the chemical ratio of protein to the plant.

One pound of sulfur for every 12 pounds of nitrogen must come from somewhere. Normally, sulfur becomes available in two ways: fall-out from rain or from the decomposition of organic matter. Since about 90 percent of the sulfur in the soil is contained in the organic matter, one can say, then, that the higher the organic matter of the soil, the less probability of a sulfur deficiency. Consequently, since sandy soils are low in organic matter content, the addition of sulfur is going to be more important than it would be on high organic soils.

Molybdenum - Molybdenum is the other plant nutrient that is necessary for the plant to convert its nitrogen to protein. Ninety percent of the nitrogen used by a plant is picked up as nitrate nitrogen even though it may be applied as ammonia or urea. This nitrate nitrogen has to be transformed into protein. If it does not convert into protein, nitrogen is unusable by the plant. So, when nitrogen remains in the nitrate form, there is rapid vegetative growth with weak cell walls causing the plants to fall over and lodge or fail to bear much fruit.

Molybdenum is the only nutrient that shows a greater deficiency problem on acidic soil than on alkaline soil. That means the greatest dollar return for molybdenum is no high nitrogen using plants in acid soils. As the pH is increased, molybdenum deficiencies become greater.