Have you ever wondered why we fertilise our lawns, gardens and vegetables? What exactly does fertiliser do? Why do you need to fertilise? Today, I'm answering these key fertilising questions and over the coming weeks we'll discuss everything you need to know about fertilising, and choosing the right fertiliser for you. 

What is Fertiliser?

Fertiliser is material of either natural or synthetic origin that can be applied to soils or plants to provide nutrients essential for growth and success.

There are three major elements found in fertiliser: Nitrogen (N), Phosphorus (P) and Potassium (K), often seen written as "NPK". They each play their own important role:

• Nitrogen builds proteins in plant cells and is important for leaf growth and chlorophyll (the green pigment).
  
  
• Phosphorus for cell formation promoting the development of seedlings, roots, flowering, fruits and seeds.
  
  
• Potassium helps in photosynthesis (the use of sunlight to create oxygen and production of sugars that help feed the plant), contributes to the plants strength, water absorption, resistance to disease, and quality of produce.

You will also find a mix of minor elements in your fertiliser: Calcium (Ca), Sulphur (S), Magnesium (Mg), Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B) and Molybdenum (Mo). They also play their own part:

• Calcium forms the cell wall structure.
• Sulphur forms part of plant protein.
• Magnesium plays an important role in photosynthesis.
• Iron is associated with the production of chlorophyll and helps carry oxygen around the plant cells.
• Manganese is essential for germination.
• Zinc is associated with the formation of chlorophyll and the plant’s intake of water.
• Copper is required for the formation of enzymes for chlorophyll production.
• Boron moves sugars through the plant, helps metabolise nitrogen, carbohydrates and hormones, and is involved in the uptake of calcium in the plant.
• Molybdenum is essential in the metabolising of nitrogen.

Why Use Fertiliser?

• Because… Nutrients! – All plants need fairly large amounts of nutrients like nitrogen and potassium, plus others listed above in smaller quantities.
  
  
• Replacing nutrients taken out from harvesting or maintenance – Unavoidably, when produce is harvested or tended to nutrients are removed from the soil. Fertiliser plays a crucial role in replacing the nutrients taken out at the time of harvest. Likewise, when your lawn is mowed it needs extra nutrients to begin re-growing its leaves.
• The bigger they are… – The better your vegetation is doing, the more nutrients it will need to keep thriving. Think of the difference between feeding a small toddler and feeding a growing teenager!
• Replacing nutrients hijacked by surrounding vegetation – Your existing vegetation will absorb more and more nutrients, putting new vegetation at risk. If you’re hoping to plant new turf, flower beds, vegetables, etc, fertilising regularly will help ensure there is enough nutrients to go around.
• High-produce vegetation – Some plants are bred to be very productive – like fruit trees and vegetables – and simply need a little extra to continue producing at their peak.
• Transference and change in environment – Not all environments are the same, so while established vegetation can thrive in one place, it may struggle in others. Ensuring the right balance of nutrients is available will be key to its success in a new environment.
• High acidity in soil (low pH) – High acidity in your soil will limit the amount of nutrients your plants can absorb. These compounds are essential to its health and success. Regular maintenance and application of fertiliser to correct these nutrient deficiencies is essential in these conditions.

Make Up & Types Of Fertilisers

There are many types of fertilisers on today’s market:

• The composition: Fertilisers may contain nutrients in different quantities. Most fertilisers are made up of an NPK mix, plus a mix of the minor or trace elements. The purpose of the fertiliser will determine its NPK make-up. Eg: NPK 10:4:12 will be higher in Potassium (K), and lowest in Phosphorus (P); which we know to be a perfect mix for lawn.
• The mechanics: Fertilisers come in varying rates of release, from instant to slow release.
• The matter: Fertilisers can be liquids or solids.
• The molecular: Fertilisers can be organic / mineral or inorganic (chemical, man-mane, artificial).

It’s important to find the right one for your purpose. If you’re growing lawn, consider a mix higher in potassium. If you’re planting Aussie natives, keep your phosphorus levels down. If you’re looking for urgent change, try a water soluble fertiliser. If you’re growing produce to eat or play on, mineral or organic will be the better choice. Etcetera, etcetera.

Over the coming weeks, we'll talk more about the things you need to know when choosing a fertiliser that's right for you; stay tuned!