When conventional soluble fertilisers are applied to the soil, the plant only consumes a fraction of the nutrients. Leaching, denifrification, volatilisation, and other processes can cause substantial losses.

Polymer & carbon coated urea is now getting cheaper. The majority of coated urea products are around 5-20% the more than the cost of straight urea fertiliser.

Nitrogen losses of 5-30% are common when topdressing urea on Crops or Pastures.

Factors contributing to losses may include

  • Soil surface drying out (includes top-dress after rainfall)
  • Losses via volatilisation can start within 24-48hrs
  • Neutral to high soil pH
  • Urea exposed to windy or warm conditions
  • Open crop canopy
  • Pasture, high trash or stubble present

Slow Release Nitrogen Products Available through Pacific Fertiliser:

  • Entec Urea (an ammonium stabiliser for nitrogen fertiliser to reduce nitrogen losses through leaching and denitrification)
  • Green Urea (contains a urease inhibitor that will help protect against volatilisation losses for upto 14 days)
  • Agrotain Urea (contains a urease inhibitor that will help protect against volatilisation losses)
  • Agromaster Urea (a controlled release polymer coated Urea, providing upto 90 day controlled release of nitrogen)
  • Nexen Urea (Agrotain stabilised urea slows the conversion of urea to ammonium, which reduces losses of nitrogen to volatilisation.
  • Carbon Coat Urea (aka Black Urea is urea coated with around 21% carbon to reduces volatilization and leaching)
  • N-Protect Urea (is a bacteriostatic inhibitor [nitrification inhibitor] meaning it won’t kill the nitrogen fixing bacteria soil population with the aim to reduces leaching and denitrification loses)

* (you can’t blend urea with entec urea for a short and longer release)

 

Controlled  Release Nitrogen Products Available through Pacific Fertiliser:

  • Polymer Coated Urea – N80 (80 day release)
  • Polymer Coated Urea – N90 (3 month release)
  • Polymer Coated Urea – N120 (4 month release)
  • Polymer Coated Urea – N180 (6 month release)
  • Polymer Coated Urea – N270 (9 month release)

 

Fertiliser nitrogen may be lost from the soil in several different ways, including; ammonia volatilisation, nitrate leaching and nitrate denitrification. Factors affecting these losses include fertiliser compound, fertiliser form, type of application, timing of application, soil properties, rainfall amount and intensity, and temperature and wind after application.

Ammonia volatilisation – is a chemical process that occurs at the soil surface when ammonium from urea or ammonium-containing fertilisers (e.g. urea) is converted to ammonia gas at high pH. Losses are minimal when fertiliser is incorporated, but can be high when fertiliser is surface-applied.

Nitrate denitrification – is a biological process that occurs within the soil profile wherever there is sufficient available nitrate, labile carbon substrate, and low oxygen conditions such as in slowly draining soils. Losses are minimal in most dryland cropping soils, but may be high in waterlogged conditions.

Nitrate leaching – is a physical process that occurs with the drainage of water through the profile. While nitrate movement within the profile is common in cracking clay soils, large-scale loss of nitrate below the root zone is minimal in most conditions.

Urea Loses – Courtesy of GRDC