Hey Guy’s sorry for the delay,
This is some basic info/background research to make an Open Source chemical analyser for the nutrient fluid in aquaponics/hydroponics systems. We really need more information about the growing fluid at our disposal to increase productivity on a grand scale but before we make a sensor we need to know what is important to measure. Check out the project Blog, we have a few contributors and shabaz has made a spectrometer from scratch already, check it out:
This Section only covers the nutrients that plants need to live, the next updates will include a section on what nutrients are harmful [ie common table salt] and my personal opinion on what are the key ones we need to measure [ones that are commonly deficient, by sampling some real world systems]. We will also cover the effect of PH on nutrient uptake at some point.
It is generally agreed that a total of only 16 elements are essential for the growth and full development of plants (1) (2). They can be split into two main groups:
Macronutrients: Needed in relatively high concentrations
Micronutrients: Relatively weak concentrations requited
Both make up the essential nutrients needed by plants. A deficiency of an essential nutrient makes it impossible for the plant to perform its necessary functions to live/grow. There are also “Beneficial" nutrients that are not essential but can have a measurable effect on a plants growth but for now we will be ignoring these as they are usually crop specific.
We could go into great detail about these, but to keep things brief we have summarised into the table below:
[Not mine but a snippet from reference (1) ]
But that doesn’t add upto 16? You are correct, the table only summarises the nutrients from the soil/growing medium. On top of that the other three are from the air:
We really only interested in the measurements of the growing fluid. So the table is the relevent ones. We will also try to measure the PH by chemical analysis [more on this in the next blog]
It would be great If we understood why these are important, but to keep it simple we will be tabling any elements/chemicals and treating them as a variable in a system [just numbers] and trying to quantify them by measurement.
If you want to learn more about why these nutrients are important these links are great:
>http://eldoradochemical.com/fertiliz1.htm [good condensed version]
>http://www.icosgroup.net/static/foodsec/text/FAO_plant_nutrition.pdf [Great Data, long read and prior knowledge would help]
- Plant Nutrition for Fodd Security . Tandon, R.N. Roy - A. Finck- G.J. Blair - H.L.S. Vols. FAO - Feritlizer and Plant Nutrition Bulition 16. http://www.icosgroup.net/static/foodsec/text/FAO_plant_nutrition.pdf.
- The essentiality of certain elements in minute quantity for plants with special reference to copper. Plant Physiol., 14: 371–375. Arnon, D.I. & Stout, P.R. 1939.