NZ Humates

Improving Urea use with Humic Material

The use of Urea for supplying Nitrogen for plant growth can be expensive as the efficiency is reduced by Ammonia volatilisation by up to 40%. Another major problem can be the loss of humus and therefore the leaching of other nutrients which can be caused through the nitrification of Nitrogen (Urea) by nitrifying bacteria and the movement of soil pH and CEC.

How does this happen?

High contents of NH4 and NO3 in the soil without good retention may not guarantee plant N use efficiency because both NH4 and NO3 are prone to leaching. The additional loss of N from soil is caused by the biological transformation of NH4 to NO3 under anaerobic condition and denitrification process of converting NO3 to N2. Under normal conditions, Ammonium (NH4+), Hydroxyl (OHS and Carbonate (CO32-) ions are produced rapidly (1 or 2 days) after surface application of Urea. This leads to the accumulation of NH4+, which simultaneously increases the soil pH surrounding the application area or near the Urea granule. The increase of OH”, HCO3″ and NH4+ concentrations through this process plays a significant role in the rapid loss of N. Rapid liberation of Ammoniacal N makes it more fragile, which promotes soluble N (e.g., NH4+) to react with other components in the soil solution and releases NH3 gas to the atmosphere.

What can be done?

    Ammonia losses can be controlled by the addition of Humic material, which contains the active ingredients Humic and Fulvic acids, at the rate of 10% to Urea. This significantly reduces the soil exchangeable Ammonia loss by up to 40 % compared to Urea alone.

    What are the other benefits?

    • Increase in soil exchangeable Ammonium and soil available Nitrate.
    • Improvement of N, P and K use efficiency as well as reducing environmental pollution.
    • Urea becomes a very stable, slow releasing Nitrogen source.
    • The released pattern is extended thus allowing 10-40% less Nitrogen to be used.
    • Humates/Humic controls the lost of humus which can be caused through the nitrification of
      Nitrogen (Urea) by nitrifying bacteria.
    • Increase accumulation of soil exchangeable Ammonium and soil available Nitrate.
    • Humates buffer the soils against damage, which can be caused by acid fertiliser applications.
    • Humates are a good source of fungi and bacteria food.
    • Decrease in Nitrates in the end product and the environment.

    If you would like to learn more about how Humates can help your farming and growing needs, please contact us on 0508 486 2837 or email us at

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