OptiU® Urea Coating

Game changing innovation for Urea Fertiliser.


What is OptiU®?

OptiU® is a non-toxic, non-hazardous liquid, which is biodegradable. When applied to solid urea particles (prills, pastilles, granules etc) it combines with the urea particle’s surface, to form a barrier film.

Once this film is established on the urea’s surface, the urea has a significantly lower affinity to form lumps or react with other fertiliser grades.

OptiU® can be described as an anti-caking coating, which improves the free-flowing characteristics as well as the compatibility, handling & storage qualities, of solid urea.

The Urea Problem

Solid urea (granular, prilled, pastilles, etc) is the most commonly used source of nitrogen in the agricultural industry.

But urea’s affinity to absorb moisture and high solubility often leads to lump formation during storage, or the CRH (Critical Relative Humidity) of a fertiliser bulk blend containing urea is lowered to a point where it becomes difficult and limiting to handle and apply.

It is also notoriously difficult, expensive and complex to treat, coat or condition urea to behave differently.

The OptiU® Solution

OptiU® is a liquid-at-ambient coating for urea fertiliser that improves the handleability of solid urea. Coated urea does not cake together, or form lumps:

It will remain free-flowing in humid bulk storage conditions.
It will remain free-flowing when bagged, even if stacked and under pressure.

OptiU® also improves the solid urea’s ability to be bulk-blended with other fertiliser grades without lowering the blend’s CRH. OptiU® can be used as the “carrier-component” for humates, NBPT molecules, nano particles of sulphur, zinc oxide, copper oxide, and many more.

OptiU® (or OptiU® containing NBPT, humates, S, ZnO, etc) are applied at ambient conditions in any standard fertiliser blending system. The coating “sets” in 60-90 seconds, to form a “barrier-film” on the solid urea’s surface. This film does not wear off or become less active over time.

fertiliser before coating
Uncoated Urea Fertiliser has a number of handling issues including moisture leeching as seen here.
fertiliser after coating
Urea coated with OptiU® ensures superior handling and storage.


Most current coatings and coating technology for solid urea is focussed on either:

  • Nitrogen release rate (or conversion rate) manipulation, or
  • Rate of moisture uptake, or
  • The addition of sulphur, or
  • The addition of humates & soil enhancers.

Urease inhibitors, PCU, SCU, Neem oil, etc are all known coating technologies, but none of these are focussed on improving the ability to handle solid urea fertiliser, or to improve the solid urea granules’ ability to be used in a bulk blend.

OptiU® is a cost effective barrier coating that is very simple to apply at any normal fertiliser dispatch-point, which drastically lowers urea’s affinity to lump together, and significantly improves the urea’s ability to be blended with most other fertiliser grades, without lowering the blend’s CRH.

There is no curing or setting time required, the coating sets within a few seconds. OptiU® coated urea can be dispatched, bagged or blended directly after the simple single–step coating process. This technology could be used to introduce nano particles of zinc oxide, cuprous oxide, sulphur etc. to the urea surface. We can even introduce NBPT molecules or humates to be part of the coating that forms a protective layer on the solid urea’s surface.

Benefits of OptiU®

Ease of Application

OptiU® can be applied in any fertiliser mixing or blending facility. The coating is applied in a simple single-step, by spraying or dribbling the coating onto urea in the mixer/blender.

The coating is not sticky, does not cause a build-up and promotes very well on urea. OptiU® can even be applied in humid conditions. No drying or curing step is required.

Cost Effective

No capital outlay required for specific or specialised equipment. The coating process also does not require any mentionable operating costs. (E.g. heating / drying or bay to cure or set)


OptiU® is made from biodegradable, not toxic or hazardous components.