The key role of potassium (K) in helping crops make the most of limited moisture has been highlighted in a trial East of Quairading.

The trial was set up to demonstrate the value of banded NPK fertilisers and compare responses to K topdressed as muriate of potash (MoP) before seeding and various liquid foliar treatments applied to the crop.

We were lucky to get the wheat crop out of the ground following sowing on 27 April, and by the 2-3 leaf stage, it was clear that the crop that was feeling the most from the dry start was sown without an NPKS fertiliser (either K-Till Max or MacroPro Extra).

Not surprisingly, in the absence of rain, plots topdressed with 72 kg/ha MoP prior to seeding showed no response to the K applied.

One of the most important roles of K in plants is to make the most of limited soil moisture – it helps the plant to extract water from the soil and retain the water that is taken up.

So, as we’re seeing in this trial, a potassium deficient crop looks like a water deficient crop. And if we’re applying K fertiliser, we need to put it where the crop can get it.


72 kg/ha MoP topdressed before seeding with 79 kg/ha Agstar Extra (11N 11P 36K)


119 kg/ha K-Till Max banded below and to the side (11N 11P 18K)

Both treatments also had 50 L/ha Flexi-N banded at seeding (21N).

James Easton
By James Easton
- Senior Agronomist

James has over 30 years’ experience working on soil and plant nutrition (crops and pastures).

He graduated from the University of Western Australia with a degree in Agricultural Science (Honours). He has in depth knowledge of historic fertiliser research trials and has worked closely with many growers, consultants, research institutions and farming groups over the years.

James gets a lot of satisfaction from sharing his knowledge with growers and those who support them. And he enjoys the fact that we are always learning.

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