To get around some nasty spray nozzle blockages, researchers have been experimenting with special clay-based 'suspension fertilisers'. According to Bob Holloway of the SA Research and Development Institute, if you add zinc and manganese to a clear solution of ammonium polyphosphate you get precipitation, then blockages of spray nozzles and angry operators. However, the use of special clays with finely divided solids, or liquids, keeps the elements in suspension and facilitates the application of the mixture.
Suspensions are very popular in the US and we have the technology to produce them here. This research is part of work on delivery systems for fluid fertilisers.
Program 4 Contact: Dr Bob Holloway 08 8680 5104