Out of Winter – P Availability

Image Credit: University of Waikato

Image Credit: University of Waikato

As we are coming out of winter in Australia, crops have gone through a period of low growth rates. The cooler soil temperatures reduce the phosphorus availability and plant uptake.(despite the volume in the soil) As the day length increases and crop heat units increase the plant growth will accelerate into spring. Plant available moisture then becomes a critical factor, the distribution of winter rainfall has been far from uniform across Australia, so every region has got varying moisture potentials.

The increased plant growth sees an increased nutrient demand. Post emergent nitrogen is being used liberally in many areas, which aids in boosting plant growth. However it is also important to remember the other nutrients the plants require. As phosphate availability is low coming out of winter, foliar applications have been found to be beneficial especially in soils that readily ‘tie-up’ phosphate. As phosphorus is a key component in plant cell development, energy and sugar production it is important to monitor and potentially factor in phosphorus applications during the high growth periods.

Micronutrient levels in the plant and availability are also important to consider and integrate with your foliar program. Micronutrients are essential for plant growth and development and also improve the efficiency of Nitrogen and Phosphorus in the plant. Micronutrients are readily adapted to spray mixes just be conscience of the form of the micronutrient and always jar test before tank mixes.


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