‘Major’ and ‘Minor’ elements

chemical elements in fertiliserChemical elements are divided up into two groups – major and minor

Major elements

  • Nitrogen (N)
  • Phosphorus (P)
  • Potassium (K)
  • Sulphur (S)
  • Calcium (Ca)
  • Magnesium (Mg)
  • Sodium (Na)
  • The tissues of plants and animals are made up of Carbon (C), Hydrogen (H), and Oxygen (O) and about 15 mineral elements.
  • The elements C, H and O along with Nitrogen (N), Phosphorus (P) and Sulphur (S) make up the living matter in plants and animals, with Calcium and Phosphorus forming animal skeletal bones.
  • The other elements are used in various body systems of plants and animals driven by enzymes and for nervous functions.
  • An enzyme is a chemical used in a biological process but remains chemically unchanged.

Minor elements

  • Boron (B)
  • Iron (Fe)
  • Manganese (Mg)
  • Copper (Cu)
  • Zinc (Zn)
  • Molybdenum (Mo)
  • Chlorine (Cl)
  • Cobalt (Co)
  • Selenium (Se)
  • Iodine (I)

MAJOR elements for plants & animals

  • There are at least 19 chemical elements required for plant growth.
  • Each chemical element has one or more specific functions within the plant, which cannot be taken over by another.
  • As the plant grows, the daily demand for nutrients increases.
  • Of the major nutrients, Mg is essential for both plant and animal growth and health, and K and Na are often involved in animal health issues.
  • The concentration of these elements in the soil can be increased by adding fertilisers, which then get into the plant and then the animal, if the animal eats sufficient of the pasture.

MINOR elements for plants & animals

The essential minor or trace elements are:

For plants:

For animals

Boron

Cobalt

Copper

Copper

Iodine

Iron

Iron

Manganese

Manganese

Molybdenum

Molybdenum

Zinc

Zinc

Selenium

 

  • All the trace elements are present in the soil, but how much and which ones get into plants depends on the soil parent material (where the soil came from), the soil pH, moisture, texture and organic matter content.
  • Old soils, which have been weathered and leached under high rainfall, have lower trace elements than young soils in drier areas.
  • As soil pH goes up, the availability of trace elements (except Molybdenum) falls. Molybdenum is more available in acid soils.
  • Soil organic matter is important in helping to bind and retain Cu, Zn, Fe and Mn in the soil.
  • Low moisture soils reduce the availability of Cobalt and Boron.
  • Over time, trace element levels are lost from a grazing system, unless replaced in fertilisers.
  • Copper is important in many aspects of animal health, and also for the nitrogen-fixing bacteria on clover roots.
  • Cobalt is important as the bacteria in the rumen use it.
  • Selenium deficiency is seen as the classical white muscle disease in lambs and calves.
  • Iodine is associated with thyroid function in animals.

Testing for trace element deficiencies

  • Laboratories can test the soil, pasture plants, and both blood and liver samples.
  • There are some very clear rules on how this should be done, so check with a testing laboratory.
  • The main concern is to prevent contamination of the pasture sample with soil, and from sweat from your hands.
  • Taking blood samples and liver biopsies on a live animal has to be done by a veterinarian.
  • Liver samples can be taken at time of slaughter, but this has to be arranged between your vet and the meat works.
  • The testing organisations will provide a reference range for each element, so you can see if they are normal or not.

Other points

  • You’ll see the terms ‘minerals’ and ‘trace elements’ used in relation to minor elements. Trace elements are as their name suggests – only needed in very small amounts.
  • So it’s obvious that with all these different elements involved in plant and animal nutrition, any one of them or a combination of only a few can put things out of balance and affect performance.
  • There’s always a great opportunity to cause panic among farmers when specialists and researchers in a particular elements report their work – giving the impression that you need to start supplementing your soil or stock with extra elements, without proper testing of soil, herbage or blood having been done.

Times to monitor trace elements

Trace element

Pasture

Liver

Cobalt/Vitamin B12

Late spring

Early summer

Selenium

Late spring

Summer

Copper

Early spring

Late autumn

Iodine

Early Autumn

Molybdenum/Boron

Summer (clover)

How much is needed to correct deficiencies?

  • Seek advice from a consultant.
  • See further reading - Morton, J., Grace, N.D., O’Connor, M.B. (1999). Their table (page 23) shows the rate of application, time of application and frequency. Note the very small amounts needed.

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