The 16 Nutrients Plants Must Have

From Chapter 14 of "Healthy Garden Healthy You" by Milo Shammas

Sixteen basic nutrients are required for crop development (plus hundreds more we know are needed in minute amounts). Commercial agriculture tends not to address these trace nutrients. The oversimplified commercial approach is like taking a multivitamin with only an emphasis on vitamin C or calcium. Conventional agriculture tells us that sixteen basic nutrients are all that is needed for plant growth

It is best to use well-rounded organic fertilizers, soil amendments, aged manures and composts for healthy plants and soil on a regular basis. You never know how much of any one nutrient is needed at a certain time of year, or time of day, for that matter. For example, nitrogen requirements can vary hourly depending on the time of day, soil temperature or the amount of photosynthesis a leaf is producing at the height of the solar index, which is from 10 A.M. to 4 P.M.

Long-lasting organic materials are great sources of nutrients and are a safe way to ensure that all nutrients are available anytime a plant needs them. I favor ocean-based fertilizers, because they are loaded with nutrients, well beyond the basic sixteen needed for crop development. All the nutrients plants use are equally important, yet each is required in different amounts. These differences have led to the grouping of essential nutrients by the relative quantities in which plants require them, namely, primary or macronutrients, secondary nutrients, and micronutrients.

The macronutrients, required in the largest amounts, are nitrogen, phosphorus and potassium (referred to by the chemical shorthand N-P-K.)  The importance of knowing your soil's pH, because many of these nutrients may never make it to your plants if the pH is out of balance.

NITROGEN (N) - Needed to produce amino acids, the building block for proteins and genetic material. Essential for plant cell division, vital for plant growth, directly involved in photosynthesis, necessary component of vitamins, aids in production and use of carbohydrates and affects energy reactions in the plant. Nitrogen enables the plant to trap energy from sunlight. Deficiency causes thin stems, yellow leaves, slowed growth and yellowing where plants should be green. Excess causes an imbalance in metabolism. Flowering and fruiting can be delayed, with fruits ripening unevenly. Bud and blossom drop, low fruit production. Fruiting and flowering plants may not develop any fruits. May also inhibit the uptake of trace nutrients. Makes plants more susceptible to insects that love young, tender growth.

PHOSPHORUS (P) - Needed for genetic material, cell membranes, root development, seed number and size. Facilitates the use of energy, involved in photosynthesis, respiration, energy storage and transfer, cell division and enlargement. Promotes early root formation and growth. Improves quality of fruits, vegetables and grains. Vital to seed formation. Helps plants survive harsh winter conditions, increases water-use efficiency, hastens maturity. Deficiency causes purple leaves beginning underneath, halted roots, slow growth, poor fruit and vegetable production. Excess Toxicity is rare but possible if phosphorus fertilizer is over applied.

POTASSIUM (K) - Needed for carbohydrate metabolism, the break down and translocation of starches and cell division. Influences the uptake of calcium, sodium and nitrogen. Increases photosynthesis and water-use efficiency. Essential to protein synthesis. Important in fruit formation. Activates enzymes and controls their reaction rates. Improves quality of seeds and fruit, improves winter hardiness, increases disease resistance. Deficiency leads to flabby stems, halted growth, burnt leaf edges and vulnerability to disease. Excess leads to deficiency in other needed nutrients, because the plant takes up extra potassium before nutrients like magnesium.

Secondary Nutrients
The secondary nutrients are calcium, magnesium and sulphur. Most crops need these three secondary nutrients in lesser amounts than the primary nutrients. People are giving them more prominence in crop fertilization programs as they learn that N-P-K fertilizers alone cannot fulfill plant requirements.

CALCIUM (Ca) – helps regulate access to plant cells similar to the ones needed for nitrogen uptake. Used for continuous cell division and formation. Involved in nitrogen metabolism. Required for enzyme activation and cell reproduction. Reduces plant respiration, aids translocation of photosynthesis from leaves to fruiting organs, increases fruit set and stimulates microbial activity. Deficiency causes all growing tips to halt, curls leaves, and causes cell membranes to disintegrate, producing thin cell walls and blossom end rot.

MAGNESIUM (Mg) – needed for the chlorophyll molecules that put the green in plants. Also used for enzyme activation. Improves utilization and mobility of phosphorus. Increases iron utilization in plants and influences earliness and uniformity of maturity. Deficiency causes yellowing of lower leaves and, in some cases, lower crop yield.

SULPHUR (S) – an integral part of amino acids needed to build proteins. Contributes to the development of several enzymes and vitamins. Aids in seed production and promotes nodule formation on legumes. Needed in chlorophyll formation. Deficiency causes younger leaves to yellow.

Micronutrients or Trace Elements
Here we cover only a few micronutrients and their importance. We know many more exist in the soil, either as minerals or as organic materials. We do not understand them fully, although we know plants need them all in minute quantities.

Micronutrients include at least iron, manganese, zinc, copper, boron, molybdenum and chloride. These plant food nutrients are used in small amounts, but they are just as important to plant development and the success of a healthy garden as the major nutrients. By making all micronutrients available to your plants naturally, you have the "multivitamin" available in the soil ready for your plants to absorb. This is the best and safest way to grow healthy plants. They are especially important because they work as activators or enablers of many plant functions. Proper pH insures many of these nutrients are available to your plants.

IRON (Fe) – important for nitrogen fixation, chlorophyll synthesis and used in other enzymes and proteins. Deficiency more likely in alkaline soil. Causes yellowing between enlarged veins and short, skinny stems.

MANGANESE (Mn) – needed for synthesis of chlorophyll, assists in vitamin, carbohydrate and nitrogen metabolism. Deficiency more likely in alkaline soil. Stops new leaf growth and pale color, mostly between veins.

ZINC (Z) – essential component of various enzyme systems for energy production, protein synthesis and growth regulation. Needed to produce plant growth hormones. Greatly benefits seed and grain production and maturation. Deficiency displays yellowing and mottling of leaves. Plants also show delayed maturity. Not mobile in plants, so zinc deficiency symptoms occur mainly in new growth

COPPER (Cu) – Important for reproductive growth. A catalyst for enzyme and chlorophyll synthesis. Aids root metabolism and helps in using proteins. Deficiency symptoms generally appear on young plants. First symptoms are yellowing of youngest leaves with slightly stunted growth. In extreme cases, leaves die after becoming shriveled, twisted, broken and ragged.

BORON (B) – important for all growing tissues. Exists in cell membranes. Needed for nitrogen fixation, protein synthesis, starch and sugar transport, root growth, water uptake and transport. Deficiency more likely in alkaline soils. May lead to growing points dying and cell disruption.

MOLYBDENUM (Mo) – Important for nitrogen metabolism and protein synthesis. Needed to convert inorganic phosphates to organic forms. Deficiency occurs mainly in acid soils. Can cause pale, deformed, thin leaves.

CHLORIDE (Cl) – Most soils have enough chloride for adequate plant nutrition. However, chloride deficiencies are reported in sandy soils in high rainfall areas or those derived from low-chloride parent materials. There are few areas of chloride-deficiency, so this micronutrient is not considered in fertilizer programs.

In addition to the 13 nutrients above, plants also require carbon, hydrogen and oxygen. Plants extract these elements from air and water to make up the bulk of their weight. Plants need micronutrients only in minute quantities to function properly. On the other hand, too much of these can be toxic, sometimes lethal, to a host organism. For this reason, avoid applying individual nutrients to prevent an accidental deficiency or over application. Adding and maintaining natural and organic matter (rock powders, seaweed, fish bone meal) is the best way to insure plants receive adequate, balanced nutrition. Natural and organic matter contains balanced amounts of the desired nutrients and can keep any excessive micronutrients from poisoning plants.

Milo Lou Shammas
Founder and Formulator

Scroll to Top