And it makes all the sense in the world, after all, when we are faced with hydroponics for the first time, the most striking and new thing for us is that the plants do not take the famous mineral salts from the soil.
By definition, in school we see that: plants need sunlight, water, and mineral salts from the soil to photosynthesize and grow. Hydroponics arrives and literally removes the base on which our plant concept is based (as the Americans say, pun intended ). The light is maintained and precisely with the amount of water we will not have problems, but: what about the happy salts?
We have removed the soil and now we have to give it the nutrients ourselves, for which we only have to decide a couple of things! How to make hydroponic formula?
Use commercial nutrient solutions.
“But tomato and lettuce are very different and will use different amounts of nutrients, right?”
Yes and no. It is true that they need different amounts of nutrients, but the plants take care of taking what they need from the water, so a commercial solution is practically the same for lettuce, tomato, or pepper. What’s more, the proportions between the salts in one or another brand of nutrients do not vary much. Although in some nutrients the instructions indicate mixing the different solutions in one or another combination according to the state of the plant (and it is a good idea to follow them), the difference between brands is not too much (it never hurts to check that it has all the nutrients). For this reason, the plants do not care much about the brand.
But there is something that does matter to them, the concentration of the salts, which we can measure with electrical conductivity (EC). The EC measures the concentration of total sales, that is, the salts that make up the nutrients and those that were already in the water.
And why does it matter? There’s a bit of science to follow, you can jump to the conclusion a couple of paragraphs below. Still here? Well. It matters because, although plants actively absorb nutrients (they put them in from the outside to the inside, expending energy), the water receives it by osmosis.
Very briefly, osmosis is a process that occurs if we have water with salts separated by a semi-permeable membrane (which only lets the water through and not the salts, as would be more or less the root of a plant). The water tends to go from the least concentrated solution (called hypotonic) to the most concentrated (hypertonic), trying to equalize the concentrations.
Osmosis process
And why does the salt concentration affect plants then? Imagine that by accident the bottle of super concentrated nutrients is overturned and we do not realize it. The nutritional solution from outside the roots will be hypertonic, so the water will flow out of the roots, literally dehydrating the plant.
Conclusion
If we go beyond the concentration of salts, there can be serious consequences for the plants. On the other hand, if we fall short, the plants will last much longer than in the other case until we put nutrients back into them.
Well, then what do we have to do? It depends on whether you have an electrical conductivity meter and want to use it or not.
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