Soil nutrients

The nutrient status of a soil tells you the nutrients that are found in the soil. They must be in the correct form and  amount for the plant.

Plant production can be changed when there is either  too much or too little of a nutrient.

A nutrient deficiency is when a nutrient or  element is lacking in the soil and this causes plant growth to be stunted or  slowed down.

The symptoms or signs that a plant shows are used to  identify the deficiency the plant is suffering.

Deficiency signs can include    a change in leaf markings, colour and slow growth.

The    mottled pattern on this bean leaf shows a deficiency.

When there is too much of a nutrient in the soil it  can be toxic or poisonous to the plant. This can result in damage to roots and  leaves.

Macro  nutrients

Macro nutrients are  nutrients that are needed in large amounts and are essential for plant growth.

The nine major elements or macronutrients are:

• carbon (C), hydrogen (H) and oxygen (O), all supplied by air or water
• nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca) and magnesium (Mg), supplied by the soil.

Nitrogen, phosphorus and potassium are needed in great  quantities by plants.

Nutrient	Use by plant	Signs of deficiency
Nitrogen (N)	part of all proteins essential for leaf and vegetative growth as it's involved in photosynthesis	stunted plants, and the older leaves go yellow fruit will be smaller and root growth restricted
Phosphorus (P)	root    growth and development production    of flowers, seeds and fruit photosynthesis and respiration    process	poor root growth bluish leaves flowers and fruit don't develop properly stunted plants
Potassium (K)	photosynthesis flower, fruit and seed development respiration	leaves look burned at edges few flowers fruit poor in colour and flavour     On    kiwifruit the leaves will become curled at the edges and the fruit may be    smaller when there is a potassium deficiency.

Calcium (Ca), magnesium (Mg) and sulfur (S) are also  important nutrients, although they are not needed in such great amounts.

Minor or trace  elements

Trace elements or micro nutrients are the nutrients  that plants need in very small quantities to maintain good health. The six  micronutrients are:

• iron (Fe)
• boron (B)
• zinc (Zn)
• manganese (Mn)
• molybdenum (Mo)
• copper (Cu).

It is extremely rare to find a normal soil lacking in  trace elements, although sandy or heavily cropped soils can sometimes have a  trace element deficiency.

The leaves on this camellia    plant have yellow edges. The soil is lacking iron, which is needed for    chlorophyll and essential for photosynthesis to take place.

Minor element deficiencies include:

• a lack of boron, which causes cracked stem in celery
• a lack of copper, which can cause citrus leaves to become dark green and twisted and develop dead patches.

What's next?

Go to: 2 Soil management and fertiliser.