Plant Nutrition Series...

Here is the first of a series of posts on plant nutrition. The following is published with permission of Hydroponic Unlimited http://www.hydroponicunlimited.com/    This website and the website owner have been very forethcoming with hydroponic system design and advice, nutrients, maintenance, and all-around hydroponic information. 

Plant Nutrients and how they are used

For testing purposes, plants are generally dried before testing. 80 to 90 percent of almost all plants is water.

About 90 percent of the resulting dry matter is made up of only three elements; Carbon, oxygen and hydrogen.

In regards to just these three elements, when you water a plant, it provides the hydrogen and oxygen and more oxygen and carbon come from the carbon dioxide from the planets atmosphere.

What these percentages tell us is that if you break down the wet weight of almost all of the plants on our planet, only 1.5 percent of that plant is made up of the remaining elements that make up a plant.

That 1.5 percent of total plant weight is made up of the 60 elements found in living plants. Of the 60 elements only some are used in each plant or plant type and they are used in varying amounts, depending on the plant type and conditions.

The elements that make up this 1.5 percent of plants have a major impact on the health and harvest of the plants. If only one of all the elements used in a plant is missing, it can quite literally kill the plant. On the other end of the spectrum, if too much of some single elements are used, it can also kill the plant.

This is why feeding a plant in a way that is balanced for that particular plant is so necessary.

Of the 60 elements found in almost all plants on our planet, only 16 of the elements are considered to be essential for growth.

In order of the percentage of each element in the dry weight of most plant matter:

45% = Carbon

45% = Oxygen

6% = Hydrogen



Macro Nutrients

1.5% = Nitrogen

1.0% = Potassium

0.5% = Calcium

0.2% = Magnesium

0.2% = Phosphorus

0.1% = Sulfur


Micronutrients

0.01% = Chlorine

0.01% = Iron

0.005% = Manganese

0.002% = Boron

0.002% = Zinc

0.0006% = Copper

0.00001% = Molybdenum
 
This article was originally published in forum thread: http://www.hydroponicunlimited.com/content.php?20-Plant-Nutrients-and-how-they-are-used]  by Hydro-1
 
Thanks Hydro-1.  As always, you have been very helpful!
 

Lettuce and Spring Starts Update, 18 April 2018

As mentioned earlier, we were very pleased at how well everything grew while we were away. Above are both systems under the lights with the Mesclun Mix on the left and the baby Simpson plants on the right. Two large salads are on the menu tonight!




The above are the Simpson as of 18 April 2011. The lettuce is 20 days from germination and 15 days in the DWC system. I posted in the grow journal, “the Simpson is very small at this stage and a bit “leggy” because of the haste required to get them into the system prior to our trip”. Normally these would have established 2 sets of healthy leaves (8-10 days) before up-potting into the hydro. I believe they will recover nicely by the color and size of the roots.





This photo shows the extensive and dense growth of the Mesclun Mix which will get a solid trimming tonight.  These are on full nutrients and are 58 days from germination and 49 days in the system.  Looks like the “reds” are getting a bit crowded.  This mix will be grown outdoors as well.

And finally, above are the spring starts of tomatoes, peppers, wildflowers, and assorted spices.  They were a bit thirsty when we returned, but are very healthy and strong.  Keeping a light breeze on them from an oscillating fan develops strong stems and curbs most risk of damping-off.  Can’t wait to get them in the beds, containers, and outdoor ebb and flow system.

Back from a short vacation

We took some risk and went on a short vacation right about the time the Simpson seedlings were to go into the DWC.  I placed the rockwool into the net pots and surrounded with silica stones.  I was concerned with light allowing algae growth as the added silica stone did not fully cover the rockwool to a depth enough to block all light.  I decided to use the 6 inch black neoprene covers I had purchased a while back and they worked nicely. 

Upon our return, we were pleasantly surprised that the leaf growth was enough to block the light so the covers were removed.  The water level had barely changed and the PH remained at around 6.2.  No change in over a week!  Each plant has solid growth and at least 5 leaves.  The stems are a bit longer than normal, but I did not have time bury deeper into the rockwool before our trip.

We left with the lights at about 2 inches above the tallest leaves in order to allow growth without fear of any type of leaf burn.  The estimate was good as the leaves were not touching, but within a half inch of the bulbs.  This shows that they had strong enough light for the week while we were out.

The Mesclun Blend is doing very well and grew over an inch vertically and at least two inches outwards while we were gone.  We titled the light angle to accommodate both the established and new plants.  This is the second get-away that the DWC proved to be maintenance free and the peace of mind is a real relief!

Pics to follow.