Hidden Hunger in Crops

What is Hidden Hunger

Whilst visual plant symptoms are very useful for identifying most nutrient deficiencies, plant growth and yields are often limited by a lack of nutrients before symptoms become evident.This sub-clinical deficiency is often referred to as ‘hidden hunger’.

Hidden hunger triggers a sequence of events in the plant when a nutrient is in short supply – and this nutrient deficiency then disturbs a plant function or structure. The plant then uses, or attempts to use, a different means to overcome the problem. If the deficient nutrient can not be overcome with the plants own adaptation mechanisms, the disruption continues and moves through a sequence of events which results in physical (or morphological) change that then becomes visible.

When these symptoms appear, the loss of productivity could be considerable and likely too late to recover lost yield potential.

The following example describes how hidden hunger results from the disturbance of an orderly hierarchy in plant function.

Example of ‘Hidden Hunger’ Effects

Assume that the plant gets ‘wet feet’. This lack of oxygen in the soil around the root zone when the soil is saturated with water for more than a day, causes the organic matter to decompose and start the process that ultimately leads to hidden hunger.

So, prior to any noticeable change in the plant, a defined sequence of events takes place.

This is as follows :


Air or oxygen in the root system escapes and anaerobic conditions (anoxia) is forced upon the root system after flooding occurs – (occurs in minutes)


Cell membrane loses its semi-permeability property – (follows on within minutes of Step-1)


Cell membranes become ‘leaky’ and loss of nutrients from roots (potassium) starts (within minutes) and continues for as long as the roots are flooded – (e.g. a day or more)


Leaves of plant lose nutrients to the root and soil via conducting tissues – (this starts within
a few hours and continues for a day or two)


Turgidity is lost since ions hold water in plants – (as a consequence of step-4)

Analogies that capture ‘Hidden Hunger’

Two other every-day analogies can be used to describe and help understand hidden hunger.

  • When a human body is not functioning at its peak due to nutrient or vitamin deficiency, we detect these shortcomings when our physical performance is affected.
    However the physiological change leading to our weakness has occurred much earlier but has escaped our notice – the hidden hunger in our body makes its mark.
  • When a motor vehicle performs at its peak it moves better and wastes less fuel (i.e. produces less heat). When it heats up, or struggles on an uphill stretch, we understand instantly that it is faulty in some way. We notice the symptom, but the fault has started the damage to the engine well before we noticed it – the hidden hunger in our vehicle makes its mark.

These two every-day analogies, when considered in terms of agricultural practice demonstrate the importance of modern management practices that eliminate the potential for this damage to occur and effect the performance of the crop.

The solution is to prevent the damage whilst it is still ‘hidden’ or undetectable.

Fertiliser Integration is ensuring an optimum balance of fertiliser at the right time – all working together in support of providing the plant with nutrient when it needs it.The message is clear – the science is in – ‘Hidden Hunger’ is the damage being done to your crop before you can detect it.

Safeguard your future yield potential and eliminate hidden hunger by implementing an RLF Integrated Fertiliser Program.



Leaves show physical sign of wilting – (this is usually observed with 1 – 2 days as a result of step-5)


Stomata pore closes


Photosynthesis is reduced or stopped – (within days)


Chloroplast system is oxidised by light and chlorophyll breaks down – (within days) and leaves turn yellow

The Solution for Eliminating Hidden Hunger

By implementing an RLF Integrated Fertiliser Program, in which nutrient levels in soil, seed and foliage is managed in a synergistic manner.

The success of fertiliser integration depends on :


Treating seeds with a seed priming fertiliser to raise phosphorus and trace element to optimum or above optimum levels. This enables the seed to set a higher yield potential, and for the seed embryo to have the nutrients required for early root and shoot
growth vigour.


Applying moderate macro nutrient to soils at optimum but not excessive levels. This is determined by fertiliser history, soil test and potential or
expected yield.


Using ultra foliar fertilisers to avoid ‘hidden hunger’ and hidden yield losses by ensuring all nutrient availability is above optimum levels. This is achieved by using specially-formulated broad-spectrum foliar fertilisers to extend the momentum of root efficiency/exploration, provide nutrient required for growth and yield and eliminate the variability of soil available nutrients.


Being aware that a fertiliser integration program is jeopardised by soil applications in excess of crop demand, thus moderate NPK input and stepwise nitrogen applications should be practised. This also reduces the cost of fertiliser programs.