Increasing the dissolution of granular fertilizers by introducing Super Absorbent Polymer (SAP)

One of the main limiting factors of applying mineral fertilizers is the need to form them into relatively large granular shapes. The reason behind this requirement is to attain compatibility with agricultural fertilizer spreader machines. These machines take in various kinds of fertilizers in solid form and spread them evenly on the field, through the action of either drop or broadcast spreaders.
If fertilizer granules are too large, then they can get stuck in the machinery, especially drop spreaders, through plugging its ports; although plugging can still be a problem even with broadcast spreaders, which have larger ports comparatively. On the other hand, if fertilizer particles are too small, i.e., in powder form, they will readily become airborne upon spreading action of said machinery, which would be a more pronounced problem with broadcast spreaders, as they will cause fertilizer powders to disperse over a wide area uncontrollably.
As with any active agent, the rate of interaction of fertilizer particles with their surroundings, and therefore their uptake by the soil and trees, depends on their surface area that is in direct contact with their surroundings. As we increase their total surface area, we will speed up their dissolution in soil and allow them to reach plants faster. To do so, we need to lower their particle size, but we are limited by the agricultural fertilizer spreader machines’ minimum granule size criteria.
So, we need to take on another approach in order to accelerate large fertilizer granules’ dissolution in soil. Along with a large surface area, high humidity is key in terms of dissolving mineral fertilizers rapidly. We propose that integrating super absorbent polymer in the structure of a mineral fertilizer granule will speed up its dissolution in soil through two modes of action.
We propose that by mixing SAP polymer homogeneously in fertilizer granules will help disruption of the fertilizer granules by water swelling of SAP and, than increased the surface area. SAP polymer will absorb water and expand several hundred’s times of their size and burst the fertilizer granules, thus small size fertilizers will be dissolved readily and access by plant root easily. Moreover, hydrophilic SAP will absorb water and retain it for a prolonged time, allowing fertilizer to be in contact with water for a longer time, compared to the typical case in bare soil. Therefore SAP will serve in two fold;  by absorbing water it will it expand, and this increase in the internal pressure will cause the SAP-fertilizer granule to burst, secondly by slow releasing water will help dissolving fertilizer prolonged time and will not washed out.