Water-dispersible granules are solid, non-dusty, granular formulations of agrochemicals that dissolve and disintegrate readily into suspensions when added to water, making them especially useful for spray applications onto plants and crops. Fertilizers, plant nutrients, herbicides, pesticides, fungicides, and insecticides are examples of formulas manufactured as water-dispersible granules. Traditionally, these have been sold to crop farmers as wettable powders or liquids. Water-dispersible granules, however, have several inherent advantages over wettable powders and liquids as they:
- Have a reduced cost to store, handle, and transport
- Minimize health hazards and risks to crop farmers
- Provide easier measurement and mixing of dry formulas
- Allow very high levels of loading for active ingredients
When it comes to the logistics of agricultural formulations, liquid formulations will always be more costly to transport, given that active ingredients are pre-suspended in water. Wettable powder formulations thus have an advantage. However, from a safety standpoint, powdered agrochemical formulations present an inhalation hazard to crop farmers, as particle sizes can be extremely small. Since water-dispersible granules do not readily erode into dust and smaller particles, they can be safely and easily measured and mixed into water on-site to make sprayable agrochemical formulas.
Formulation of Agrochemical Water-Dispersible Granules
A typical water-dispersible granule formulation for agriculture may contain disintegration, binding, and wetting agents, stabilizers, fillers, and the active ingredient itself. Granules may be formed via dry granulation or wet granulation techniques using an extruder, depending on if any agrochemical components of the granule are sensitive to heat or moisture. In the case that these components are sensitive to heat and moisture, the dry granulation technique is preferred.
To realize all the benefits of water-dispersible granules discussed in the previous section, one key property must be achieved when considering the formulation. The water-dispersible granule must be readily and easily dissolved in water. Thus, the right disintegration and dissolving agent must be selected.
Accelerate® DS-813 is an internally crosslinked carboxymethyl cellulose (sodium croscarmellose) that is specifically designed to promote rapid disintegration and dissolution of water dispersible granules in agricultural applications. It is an aid added to granules at low percentages and is compatible with various granulation processes, including wet granulation. When agrochemicals are dissolved using Accelerate® DS-813, the need for dispersants and formulation components such as emulsifiers may be reduced. An SEM image of Accelerate® is seen below.