2.6 Principles of Nutrition

Macro Nutrients

There are 10 major or macro nutrients required by plants. Figure 1 contains details of these including their source. In production soils in South Australia nitrogen, phosphorus and sulphur are often deficient and need to be manipulated to improve soil productivity.

Figure 1: 
Macro nutrients, requirement and source

Micro nutrients/ trace elements

There are 7 micro nutrients or trace elements that plants require for growth . These are only required in small amounts but a deficiency of any trace element in the soil can limit plant growth even when all other essential elements are present in adequate amounts. In South Australian soil zinc, manganese and copper are often deficient or insufficiently available. In acid soils molybdenum availability is reduced often resulting in crop deficiency.

Total soil content does not necessarily indicate the level of nutrient available for plant growth.

Figure 2:
Micro nutrients, range of soil contents and optimum pH range for availability

Figure 3
Nutrients removed by 1 tonne of grain

Calculating fertiliser application rates

Multiply the percentage of active ingredient by the kilograms applied per hectare and divide by 100 to give the kilos of nutrient applied

For example:

2.6 Principles of Nutrition

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