The most important nutrient for your crops and pasture health is not always the one you apply the most regularly, it is the one in shortest supply. This is known as the law of the minimum: plant growth is limited by its most deficient nutrient, not by the total amount of nutrients available.
Plants need 16 essential nutrients to complete their life cycle: split into macronutrients, like Nitrogen (N), Phosphorous (P), and Potassium (K) and micronutrients, like Zinc (Zn), Molybdenum (Mo), and Boron (B). Though macronutrients are needed in larger quantities, all nutrients play a vital role, and any shortfall can limit production.
A substantial proportion of a plant’s dry weight (some 90 to 95 percent) is made up of three nutrients—Carbon (C), Hydrogen (H), and Oxygen (O) which come directly from the atmosphere and water. The soil should supply the remaining 13 nutrients in the right amounts, but this is not always the case.
Why nutrient deficiencies happen
There are several reasons behind nutrient shortages:
- Not enough nutrients available in the soil
- Soil pH that is too high or too low
- Environmental conditions (like dry, wet, or cold weather) affecting uptake
- Unsuitable soil structure.
If left unchecked these deficiences lead to reduced growth and yield.
What is foliar nutrition?
Solid fertilisers are the backbone of most nutrient programmes; however, foliar feeding is a great short-term fix, especially when things are not going to plan.
Foliar nutrition is the practice of spraying nutrients directly onto the leaves of the plant. It is not designed as a replacement for solid fertiliser, but rather as a complement. It is most effective when used to:
- Quickly correct nutrient deficiencies
- Deliver trace elements that plants can find hard to access in the soil
- Give crops a short-term boost during stressful growing conditions.
Benefits of foliar nutrition
- Fast response: nutrients absorb straight into the leaf
- Precise application: ideal for micronutrients
- Save on application: tank-mix with compatible crop protection products to save on passes.
If you observe uneven growth, pale leaves, or underperforming areas in your paddocks, foliar nutrition might be worth considering. It is a practical management tool that, when used wisely, can help you keep things on track.
TECH TIPS
- Fixation by clover is slow and the rate of N and Sulphur (S) mineralisation from your soil organic matter can be low in early spring. Fertilisers containing N and S are a good option to drive early spring pasture growth.
- On soils with low Cation Exchange Capacity (CEC), and therefore prone to K leaching, spring is a good time to apply K fertiliser.
