Plant
Nutrients
|
Sixteen chemical
elements are known to be important to a plant's growth and
survival. The sixteen chemical elements are divided into two main groups:
non-mineral and mineral.
|
|
Non-Mineral
Nutrients |
|
The Non-Mineral
Nutrients are hydrogen (H), oxygen (O), & carbon
(C). |
|
|
These nutrients are
found in the air and water.
In a process called
photosynthesis, plants use energy from the sun to change
carbon dioxide (CO2 - carbon and oxygen) and
water (H2O- hydrogen and oxygen) into starches and
sugars. These starches and sugars are the plant's food.
Photosynthesis means "making things with
light". |
|
Since plants get carbon,
hydrogen, and oxygen from the air and water, there is little farmers and
gardeners can do to control how much of these nutrients a plant can
use. |
|
Mineral Nutrients |
|
The 13 mineral
nutrients, which come from the soil, are dissolved in water and
absorbed through a plant's roots. There are not always enough of these
nutrients in the soil for a plant to grow healthy. This is why many
farmers and gardeners use fertilizers to add the nutrients to the
soil.
The mineral nutrients
are divided into two groups:
macronutrients and micronutrients.
Macronutrients
Macronutrients can be
broken into two more groups:
primary and secondary
nutrients.
The primary
nutrients are nitrogen (N), phosphorus (P), and potassium (K). These major nutrients
usually are lacking from the soil first because plants use large amounts
for their growth and survival.
The secondary
nutrients are calcium (Ca), magnesium (Mg), and sulfur (S). There are usually enough
of these nutrients in the soil so fertilization is not always needed.
Also, large amounts of Calcium and Magnesium are added when lime is applied to
acidic soils. Sulfur is
usually found in sufficient amounts from the slow decomposition of soil
organic matter, an important reason for not throwing out grass clippings
and leaves.
Micronutrients
Micronutrients
are those elements essential for plant growth which are needed in only
very small (micro) quantities . These elements are sometimes called minor
elements or trace elements, but use of the term micronutrient is
encouraged by the American Society of Agronomy and the Soil Science
Society of America. The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). Recycling organic matter
such as grass clippings and tree leaves is an excellent way of providing
micronutrients (as well as macronutrients) to growing
plants.
Go to top of the
page
|
|
Soil |
|
In general, most plants
grow by absorbing nutrients from the soil. Their ability to do this
depends on the nature of the soil. Depending on its location, a soil
contains some combination of sand, silt, clay, and organic matter. The
makeup of a soil (soil texture) and its acidity (pH) determine the extent
to which nutrients are available to
plants. |
|
|
Soil
Texture (the amount of sand, silt, clay, and organic
matter in the soil)
Soil texture affects how well
nutrients and water are retained in the soil. Clays and organic soils hold
nutrients and water much better than sandy soils. As water drains from
sandy soils, it often carries nutrients along with it. This condition is
called leaching. When nutrients leach into the soil, they are not
available for plants to use.
An ideal soil contains
equivalent portions of sand, silt, clay, and organic matter. Soils across
North Carolina vary in their texture and nutrient content, which
makes some soils more productive than others. Sometimes, the nutrients
that plants need occur naturally in the soil. Othertimes, they must be
added to the soil as lime or
fertilizer.
Soil pH (a measure of the
acidity or alkalinity of the soil)
Soil pH is one of the
most important soil properties that affects the availability of
nutrients.
- Macronutrients tend to be less available in
soils with low pH.
- Micronutrients tend to be less available in
soils with high pH.
Lime can be
added to the soil to make it less sour (acid) and also supplies calcium
and magnesium for plants to use. Lime also raises the pH to the desired
range of 6.0 to 6.5.
In this pH range,
nutrients are more readily available to plants, and microbial populations
in the soil increase. Microbes convert nitrogen and sulfur to forms that plants can use. Lime also enhances
the physical properties of the soil that promote water and air
movement.
It is a good idea to
have your soil
tested. If you do, you will
get a report that explains how much lime and fertilizer your crop
needs.
Go to the top of the
page
|
|
Macronutrients |
|
Nitrogen (N) |
- Nitrogen is a part of all living cells and is a
necessary part of all proteins, enzymes and metabolic processes involved
in the synthesis and transfer of energy.
- Nitrogen is a part of chlorophyll, the green
pigment of the plant that is responsible for photosynthesis.
- Helps plants with rapid growth, increasing seed
and fruit production and improving the quality of leaf and forage
crops.
- Nitrogen often comes from fertilizer application
and from the air (legumes get their N from the atmosphere, water or
rainfall contributes very little nitrogen)
|
|
Phosphorus (P) |
- Like nitrogen, phosphorus (P) is an essential
part of the process of photosynthesis.
- Involved in the formation of all oils, sugars,
starches, etc.
- Helps with the transformation of solar energy
into chemical energy; proper plant maturation; withstanding stress.
- Effects rapid growth.
- Encourages blooming and root growth.
- Phosphorus often comes from fertilizer, bone
meal, and superphosphate.
|
|
Potassium (K) |
- Potassium is absorbed by plants in larger amounts
than any other mineral element except nitrogen and, in some cases,
calcium.
- Helps in the building of protein, photosynthesis,
fruit quality and reduction of diseases.
- Potassium is supplied to plants by soil minerals,
organic materials, and fertilizer.
|
|
Calcium (Ca) |
- Calcium, an essential part of plant cell wall
structure, provides for normal transport and retention of other elements
as well as strength in the plant. It is also thought to counteract the
effect of alkali salts and organic acids within a plant.
- Sources of calcium are dolomitic lime, gypsum,
and superphosphate.
|
|
Magnesium (Mg) |
- Magnesium is part of the chlorophyll in all green
plants and essential for photosynthesis. It also helps activate many
plant enzymes needed for growth.
- Soil minerals, organic material, fertilizers, and
dolomitic limestone are sources of magnesium for plants.
|
|
Sulfur (S) |
- Essential plant food for production of protein.
- Promotes activity and development of enzymes and
vitamins.
- Helps in chlorophyll formation.
- Improves root growth and seed production.
- Helps with vigorous plant growth and resistance
to cold.
- Sulfur may be supplied to the soil from
rainwater. It is also added in some fertilizers as an impurity,
especially the lower grade fertilizers. The use of gypsum also increases
soil sulfur levels.
|
|
Go to the top of the
page
|
|
Micronutrients |
|
Boron (B) |
- Helps in the use of nutrients and regulates other
nutrients.
- Aids production of sugar and carbohydrates.
- Essential for seed and fruit development.
- Sources of boron are organic matter and borax
|
|
Copper (Cu) |
- Important for reproductive growth.
- Aids in root metabolism and helps in the
utilization of proteins.
|
|
Chloride (Cl) |
- Aids plant metabolism.
- Chloride is found in the soil.
|
|
Iron (Fe) |
- Essential for formation of chlorophyll.
- Sources of iron are the soil, iron sulfate, iron
chelate.
|
|
Manganese
(Mn) |
- Functions with enzyme systems involved in
breakdown of carbohydrates, and nitrogen metabolism.
- Soil is a source of manganese.
|
|
Molybdenum (Mo) |
- Helps in the use of nitrogen
- Soil is a source of molybdenum.
|
|
Zinc (Zn) |
- Essential for the transformation of
carbohydrates.
- Regulates consumption of sugars.
- Part of the enzyme systems which regulate plant
growth.
- Sources of zinc are soil, zinc oxide, zinc
sulfate, zinc chelate.
|
|
Go to the top of the
page
|
|
