Solubility

Dicalcic

Superphosphate

More citric-soluble than water-soluble, so less chance of runoff, product waste and environmental impact.

Very water soluble so more chance of runoff and leaching, particularly on hill country.

Mixed with seed

Dicalcic

Superphosphate

Close to pH neutral so won’t burn seed, which means more cost-effective sowing.

Can’t be mixed with seed because of its high acidity and potential to burn seed. Separate applications of superphosphate, lime and seed. More spreader time and more management time.

Application

Dicalcic

Superphosphate

Calcium (lime) and phosphate blended in one granular fertiliser, so one low maintenance application.

 

Cost-effectiveness

Dicalcic

Superphosphate

The effectiveness of application, combination of multiple nutrients and product efficiency really do pay off in dry matter production and stock performance.

While unit price may look lower, the cost of application, product effectiveness and environmental impact can impact this significantly.

Soil condition

Dicalcic

Superphosphate

With its liming effect, helps neutralise soil pH to maintain optimum growing conditions, making soil nutrients more readily available.

Has no liming effect, which can mean lower yields if lime isn’t used to improve soil health.

Environment

Dicalcic

Superphosphate

Low water-solubility, so little risk of runoff and leaching; you use less P because of product effectiveness.

Highly water-soluble so its use entails the risks of leaching, runoff, and product wastage.

Nutrient release

Dicalcic

Superphosphate

Slow, sustained-release P is only released when plant needs it making dicalcic phosphate more effective and efficient over time.

Water-soluble, so depending on rainfall, P can be released very quickly oversupplying plants or running off.

Citric-soluble vs. Water soluble?

The key difference between superphosphate and Dicalcic is the way plants uptake the nutrients these products provide… 

  • Water-soluble products like superphosphate break down quickly on contact with water.
  • Citric soluble products with lower water-solubility need acidity from the soil and plant to release nutrients.
  • If a product is highly water-soluble its effectiveness can be greatly reduced in wet conditions, with the P released immediately and washed or leached away.
  • Products with lower water-solubility need acid from the soil and plant to release their P – they offer a slower, more sustained release of soil nutrients. And because they use soil acid to release their P, this also helps reduce soil acidity to bring it in line with optimum growing conditions – a pH of around 6. 

Dicalcic is citric-soluble, much less water-soluble than super, giving you a strong, medium release P fertiliser without the risk of product wastage because of runoff.

 

Citric Solubility (CSP)

Water Solubility (WSP)

Replenish (RPL)

>65%

<48%

uPgrade

>56%

<9%

Reactive phosphate rock (RPR)

>30%

 0%

Superphosphate (SSP)

>85%

>78%

Note: Figures derived for RPL & uPgrade are values from sampling programme

WSP Upper limit = average + SD

CSP lower limit = average - SD