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Plant
nutrients are the chemical elements which are essential components of plant
tissue. For healthy growth, plants require an adequate supply of each of these
elements. The most abundant elements in plants, carbon (C), oxygen (O) and
hydrogen (H), are obtained from the air and water. The others, referred to as
the mineral nutrients, are supplied by the mineral and organic components
of the soil. These are divided into 2 groups, the macronutrients (or
major elements) which plants need in relatively large amounts (from 0.1 to 6 %
of dry plant material), and the micronutrients (or trace elements) which
are needed in much smaller amounts (in the order of 0.1-100 mg per kg dry
weight).
List
of macronutrient and micronutrient elements
required
for the healthy growth of all plant species.
|
Macronutrient |
Symbol |
Micronutrient |
Symbol |
|
Nitrogen |
N |
Iron |
Fe |
|
Phosphorus |
P |
Boron |
B |
|
Potassium |
K |
Manganese |
Mn |
|
Calcium |
Ca |
Zinc |
Zn |
|
Magnesium |
Mg |
Copper |
Cu |
|
Sulfur |
S |
Molybdenum |
Mo |
In addition to the elements listed above, there is a small
number of elements which have been found to be needed by some plants or under
some circumstances. These are called beneficial elements. Beneficial
elements include cobalt (which is needed for biological nitrogen fixation),
sodium, and silicon. Chlorine and Nickel are also essential elements, but
deficiencies are never encountered in the field.
A deficiency of any one nutrient results in a reduced growth
rate and yield of the crop. The problem can only be corrected by increasing the
supply of that nutrient. Therefore, it is important to diagnose a nutritional
disorder correctly, in order to treat it efficiently.
Many mineral nutrients (including B, Cl, Mn and Cu) are toxic
to plants if they are present at high concentrations. Some other elements, which
are not essential nutrients for sweet potato, may also cause toxicity. These
include aluminium (Al), a problem in acid soils, and sodium (Na), in saline or
sodic
soils.
Contributed
by:
Jane O'Sullivan |
Further
topics on Soil Management:
Soil management
Soil
structure
Soil
organic matter
Fertilisation
Causes
of nutritional disorders
Diagnosing
nutritional
disorders
Correcting
nutritional
disorders
Other topics on Crop Management: Land
preparation
Planting
material preparation
Planting
Water
management
Vine
lifting
Integrated
pest management
Harvesting
Postharvest
practices
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