BLOCKAGES!

In this week's episode we delve into the issues around filter and nozzle blockages. We pay particular attention to the problems that can arise when mixing various biological products and how to overcome them.

 

Fish-based organic fertiliser

Most commonly extracted using phosphoric acid. Phosphorus often reacts with soluble calcium to form insoluble calcium phosphate. Once this forms, it isn’t going anyway, no matter how much you rinse the system. So avoid calcium containing products when using fish-based fertiliser, or do a bucket test first.

The other issue with many organic fertilisers, including those based on fish, is that they are commonly suspensions, not soluble concentrates. As such, if left for a long period of time in the spray tank they may settle out and form a layer along the bottom of the tank. Therefore, do not store diluted product overnight. Storing diluted biologicals is also never advised because it will stimulate microbial growth and the additional problems that come from that if not precisely controlled.

 

Molasses-based organic fertilisers

When it comes to molasses it is the actual water you need to take care with. If you pour molasses quickly into very cold water it can sink to the bottom of the tank in one big solid lump! If that lump is sucked into a mixing pump it can cause a catastrophic failure. Therefore always add molasses slowly to any tank and agitate continuously. Alternatively, pre-dilute the molasses in some warm water before adding to the tank for further dilution to the spray concentration. 

 

Seaweed extracts

Confirm the pH first. Some are acidic, some neutral, but more commonly they are alkaline. If alkaline, avoid any product that will lower the pH and bring the carbohydrate (alginic acid etc) solids out of solution.

Always avoid mixing with chitosan. As chitosan is acidic and cationic (seaweed extracts are anionic); any mix of these two will result in something with the appearance of vomit! If this doesn’t happen, you are using poor quality seaweed extract and/or chitosan solution.

 

Humic and fulvic acid

Humic acid solutions are very often moderately alkaline. So avoid any acidic product that will bring the pH down. If this happens you will get a thick tar coating your filters.

We have seen a few cases recently of issues when tank mixing with citric acid. This has happened because farmers are now hearing that the efficacy of glyphosate (Roundup) can be increased by lowering the pH with citric acid. They are also hearing that the efficacy of glyphosate can be increased by the inclusion of humic or fulvic acids. So they have applied all three products to the spray tank and blockages have occurred. 

 

Chitosan

In addition to its use as a biostimulant and biofungicide, chitosan can also be used to remove contaminants from wastewater. Chitosan is used in waste water treatment because it binds to contaminants and takes them out of solution. So while removing bacteria, metal ions, and humic acid might be an advantage in that scenario, in a spray tank the opposite is true.

Chitosan can be tank mixed with a variety of conventional agrochemicals and biologicals, but you need to do your homework first, and always conduct a bucket test with the dilution ratios and water you plan on using. If you need a small sample to do a tank mix with, then please get in touch.

I always used to tell customers to never mix chitosan with silicon fertilisers, as these are alkaline and will also fall out of solution if mixed incorrectly. Howev