Phosphate: Improving use efficiency & maximising your fertiliser investment

The nutrient phosphate is vital for plant growth and overall health.

Its functions, which include energy transfer, photosynthesis, the transformation of sugars and starches, nutrient movement within the plant and the transfer of genetic characteristics, cannot be performed by any other nutrient.

Therefore, an adequate supply of phosphate is required in crops as, when it is deficient, it can lead to many significant issues with plant health. These include:

  • A reduction in leaf expansion and leaf surface area, as well as the number of leaves.
  • A decrease in the shoot-root dry weight ratio.
  • Less root mass to reach water and nutrients.

Given the current market situation, it is vitally important for farmers to get the most out of their phosphate purchase, and that’s where the team here at McCreath Simpson & Prentice (MSP) can assist.

The table below outlines the importance of having the correct soil pH ahead of any fertiliser application.

As you can see, when the soil pH is 6.0, the efficiency of phosphate is almost halved to 52% – significantly more affected than both nitrogen and potash – meaning 48% of the investment in phosphate is not utilised in the growth of the crop.

As a result, we must stress the importance of regular and accurate soil sampling for soil pH.

Variable applications of lime help to condition soils to the optimum pH for all areas of the field, not just a whole-field average, maximising the return from your fertiliser investment.

At MSP, our team of BASIS & FACTS qualified agronomists will work with you to produce precision pH sampling, variable lime application recommendations and mapping, as well as nutrient management plans.


We’ve also conducted our own trials, with the results of this strongly suggesting that autumn applied Polysulphate fertiliser increases nutrient uptake, particularly that of phosphate.

The table below highlights this.

Polysulphate is a naturally occurring multi-nutrient sulphate fertiliser produced by ICL that contains four major plants nutrients – sulphur, potassium, magnesium and calcium – all in the sulphate form and fully available to the crop.

Polysulphate is also pH neutral (7.0), reducing the need for liming.

As well as increasing nutrient uptake, our trials – operated in conjunction with ICL – showed that Polysulphate stimulated and increased root growth.

A mere 1cm increase in root length provides the crop with access to an additional 130 tonnes per hectare of soil and all the additional phosphate and other nutrients found there.

Therefore, Polysulphate improves phosphate use efficiency which, ultimately, results in better plant health and a greater yield from the finished crop.

As well as Polysulphate, at MSP we can also offer our customers PKpluS from ICL, which is a high-quality granular fertiliser with Polysulphate incorporated into it.

If you have any questions about the subject of this blog on phosphate, contact your farm rep or get in touch with us today.