@_Maq_ this is really interesting to me. Do you believe that plants roots can access and use these nutrients once precipitated? And do you think there's a chance that this precipitate could lead to toxicities?
In "Hydroponics - A Practical Guide for the Soilless Grower", they have a section detailing something like this.
Now, hydroponics are of course not exactly the same as aquatic growing, but still I found it interesting to read about.
I'll take the liberty to share the section with you guys
However if one is interested in reading more about nutrients and these kinds of things, I can recommend reading the entire book 😊
Accumulation in the Rooting Medium
It is well known that with each application of a nutrient solution to a rooting medium, whether inorganic (sand, gravel, perlite, rockwool, etc.) or organic (pinebark, peat, coir, etc.), an accumulation of unabsorbed ions takes place. This can be observed by monitoring the EC of the solution exiting or in the rooting medium following a sequence of nutrient solution applications. When that EC measurement reaches a certain level, it is recommended that the rooting medium be leached with water to remove the accumulate. What is not as well known is that another type of accumulation occurs — the formation of precipitates consisting mainly of calcium phosphate and calcium sulfate. As those precipitates form, additional ions can be adsorbed on their surface or chemically combined with the forming precipitates. These precipitates do not contribute to the EC of the medium solution and are not easily leached from the rooting medium by water. The elements in the precipitates then begin to contribute to the elemental nutrition of the growing plant. Roots release acid into the rhizosphere surrounding the root, which dissolves a portion of these precipitates. With time, the accumulated precipitates begin to more strongly influence the plant element nutrition than that being applied by the nutrient solution for some elements. This partially explains why growers seem to lose control of the nutritional character of their crops over time.
My interpretation of this is that yes, the precipitates could affect the plants over time. However we should consider when comparing our systems to hydroponic systems, that we usually use much less nutrients in our water than they do in their water.
But, I suppose a method of fertilization like EI might "sooner" produce precipitate than a leaner method might, purely on the basis of the amount of nutrients being added.
I wonder if this is one of the reasons some people find it useful to periodically clean out their substrate? The commonly cited reason is detritus etc (another debate is on whether detritus is all bad, mixed, or purely beneficial, which I will not get into here), but maybe removing precipitates may be a hidden benefit of a "spring cleaning". For example, Marian Sterian (who makes the Masterline ferts and grows some
pretty nice plants) advises a cleaning and reset of the substrate every 3-4 months (I believe). However I cant say exactly why he does this as I do not know.
Im pretty far off topic now to the original frogbit deficiency, and most dont keep their frogbit rooted into the substrate as far as I know, so maybe we should continue this in a new thread? That way others may also find the discussion more easily, if it has a descriptive title instead of ending up buried in another topic 😃
