Trace elements in the soil - Soil Essentials: Managing Your Farm's Primary Asset - page 44

The limiting factor concept
Limitations to plant and animal growth and health can often be determined by
individual trace element deficiencies or toxicities when every other requirement for
growth and health is present. This can also apply if too much of a nutrient is
available that can either become toxic, or cause a deficiency of another nutrient due
to an antagonistic effect. If this is the case, nutrient levels must be balanced to return
the soil to a healthy state, which in turn can support healthy plants that will provide
good food to grow healthy animals. Table 9 lists the most important trace elements.

Table 9 The more important trace elements

Element Symbol

Boron B

Chlorine Cl

Cobalt Co

Copper Cu

Fluoride Fl

Iodine I

Iron Fe

Manganese Mn

Molybdenum Mo

Selenium Se

Silicon Si

Sodium Na

Sulphur S

Zinc Zn

Soil tests
One method of determining the state of trace elements in the soil is to do chemical
soil tests. These tests allow the land manager to design a precise fertiliser program
to fully meet the needs of the soil, plants and animals. Potentially this will result in
better responses to applied fertilisers, and give better returns for invested capital
and labour, and healthier animals.

Tissue testing
By testing plant tissue for nutrient content, deficiencies can be measured and a
fertiliser program can then be developed to address any problems found. If this
method is used, plant tissues must be collected from the correct part of the plant at
the correct time of year.