LESS IMPACT ON THE ENVIRONMENT

Adding maximum fertility for minimal runoff loss.

Our fertilisers both minimise the total amount of phosphorus used, and keep a steady supply in the soil throughout the growing seasons.

TerraCare has been researching and developing phosphate fertilisers for farms, orchards and nurseries for more than 20 years. Our fertilisers both minimise the total amount of phosphorus used, and keep a steady supply in the soil throughout the growing seasons.

Not all of the processes in the phosphate cycle can be affected by the type of phosphorus fertiliser used – but one part that can, is the area where the fertiliser interacts with the soil (Fig. 5).

We know this from historical experimental and trial work using superphosphate-type (SSP) fertilisers. SSP fertilisers contain phosphate in the form of monocalcium phosphate (MCP). When MCP reacts with moist soil, it forms both dicalcium phosphate (DCP) and phosphoric acid (PA).

The PA makes the soil around the fertiliser particles much more acidic – its pH levels can become as low as pH 1.5 – which causes aluminium (Al) and iron (Fe) to be released in soluble form. These two elements bind the phosphate released as PA, making it insoluble and less available to the plants than DCP. This process is called fixation.

TerraCare’s DCP phosphate fertilisers are less acidic and provide a constant steady release of phosphorus, which is immediately plant-available. This is a direct contrast to reactive rock (RPR) fertilisers: though they don’t release PA, they do contain phosphorus in a form that may not be plant-available for several months/years.

Efficiency

TerraCare products are all about efficiency: we reduce nutrient losses to make sure you get the most from your investment, as well as minimise the impact on the environment (Fig. 6).

Phosphate is mainly lost through surface runoff, carried along as fine soil particles are washed away.

The soil P test levels only need to be at, or close to, the optimum for plant growth. There’s no economic benefit to higher levels, which also pose an environmental risk.

Dicalcic (or dicalcium) phosphate is produced through monocalcium phosphate (or superphosphate) reacting with calcium, the main element in lime. In chemical terms:

monocalcium phosphate + calcium = dicalcium phosphate
Ca(H2PO4)2 + Ca = CaHPO4

This new substance has completely different characteristics:

  • Low water solubility, turning a fast releasing MCP into a slow release fertiliser
  • High citric solubility, with plants causing the P to dissolve and make it available

The combination of low water-solubility and high citric solubility means a reduction in losses due to leaching and runoff, and that growing plants can receive phosphorus as fast as they need it.

TerraCare’s DCP is produced carefully to ensure that we make the most of these characteristics. We use a granulator to expose the products to each other in a lower volume, but for a longer time. We then post-cure it for several weeks to complete the reaction.

Granulation means improved spreadability, as well as ensuring that the fertiliser behaves exactly as dicalcic phosphate should.

TerraCare is Fertmark registered; our products are independently checked and controlled to ensure consistent high quality.

Nitrogen

Nitrogen is a highly mobile element. In general, we can expect to lose up to 50% of applied nitrogen through leaching and volatilisation.

While nitrogen loss is undesirable both in terms of investment and environment, there are ways to mitigate this. Clover-fixated nitrogen is one way to provide slow-release nitrogen, making it available throughout the seasons through mineralisation.

Another way is to use a nitrification inhibitor, which can slow down nitrogen release for a time, but is still not ideal for a long time release.

However, TerraCare CoatN is a proven alternative – it’s a controlled-release, polymer-coated urea that improves the efficiency of the nitrogen, meaning you use less overall. (Fig. 7).

Slower and more efficient nitrogen release means:

  • Fewer applications are needed, reducing field movement and preserving the soil structure and microorganisms
  • Reduced costs on labour and spreading
  • Lower urea application leads to less chance of damage from crop leaf burning
  • The pasture grasses and clover composition remain as they were before application
  • Less damage to clover nitrogen fixation in pastures
  • Less impact on the environment from volatilisation and runoff