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Roger Weller, geology instructor

wellerr@cochise.edu

Hydroponics
by N.P.
Physical Geology
Fall 2014
  
 
 

Hydroponics
 

 

What is hydroponics? Hydro- is Greek, meaning water or liquid. -Ponic is also a Greek word for labor. Thus, we get the interpretation that water is doing work. This is a great interpretation because water is the driving force behind any hydroponics system. Water is already important for plants, but, it becomes very important in a hydroponics system because of this “work” that it does. What sets hydroponics apart is one simple idea: that plants do not need soil. They need minerals, but, they do not need the clay, sand, or “dirt” that plants are typically seen growing in.  In a hydroponics system water must carry all of the mineral nutrients that a plant needs without “over watering” or “suffocating” a plant.

 

Description: http://www.hydroponics.name/wp-content/uploads/2013/01/Hydroponics_2.jpg

Lettuce is one of the most popular hydroponics plants.

 

Before developing a system to care for a plants need, it is important to understand what those needs are. In all, there are sixteen critical chemical elements that any plant needs to grow and live. Thirteen of these are traditionally derived from the soil and material in which a plant grows, these are the mineral nutrients. The other three: hydrogen, oxygen, and carbon are all found naturally in air and water. The mineral nutrients are broken down into several sub-categories because of importance and availability. First, there are two main categories: Macronutrients and Micronutrients. Macronutrients are needed in significant quantities for growth while Micronutrients are only needed in a comparatively small amount. Macronutrients are also divided into two more categories, primary and secondary nutrients. The primary nutrients are used in very large amounts and are typically at less than optimal in a soil which has grown plants for any extended period of time. The secondary nutrients are depleted far less quickly and are more easily returned to the soil when a dead plant decomposes.
 

 

Macronutrients

Micronutrients

Primary

Secondary

Boron

Nitrogen

Calcium

Copper

Phosphorous

Magnesium

Iron

Potassium

Sulfur

Chloride

 

Manganese

Molybdenum

Zinc

For a detailed breakdown of how each chemical element effects a plant visit:
http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm

 

These are the minerals needed from a traditional soil. However, with hydroponics, we take soil out of the equation; instead, we use water to transport these minerals to the plant. This is the hydroponic solution; note that the name can be somewhat misleading as this is not a true solution. For example, copper is not water soluble, but, the water can still transport the mineral to a plant. Also, it should be acclaimed that all plants need these minerals, but, not in the same amounts. Most solutions should have the correct proportion of minerals mixed exclusively for one plant.

 

 

Pre-mixed hydroponic solutions are available, but, usually they can only be used as a starting point since most solutions are tailored to certain plants.


 

 

 

 

Stage of growth

 

1

2

3

4

5

Nutrient

Transplant to

1st cluster

1st cluster to

2nd cluster

2nd cluster to

3rd cluster

3rd cluster to

5th cluster

5th cluster to

termination

 

--------------- Final delivered nutrient solution concentration (ppm)z --------------

N

70

80

100

120

150

P

50

50

50

50

50

K

120

120

150

150

200

Ca

150

150

150

150

150

Mg

40

40

40

50

50

S

50

50

50

60

60

Fe

2.8

2.8

2.8

2.8

2.8

Cu

0.2

0.2

0.2

0.2

0.2

Mn

0.8

0.8

0.8

0.8

0.8

Zn

0.3

0.3

0.3

0.3

0.3

B

0.7

0.7

0.7

0.7

0.7

Mo

0.05

0.05

0.05

0.05

0.05

NOTE: Ca, Mg, and S concentrations may vary depending on Ca and Mg concentration in wellwater and amount of sulfuric acid used for acidification.

z 1ppm = 1mg/liter

An example recipe used for tomatoes at the University of Florida.
More information on formulating recipes is found at their site:
http://edis.ifas.ufl.edu/cv216

 

Now that we have water and minerals sorted out we need to determine how a plant can use them. Unfortunately, it’s not as simple as pouring minerals in water, and pouring that water onto a plant. The plants will absorb the minerals through their roots, but, plants also absorb oxygen through their roots. As a result, it’s important to not submerge the roots completely, or at least, not for lengthy periods of time. A few ways to prevent this is to have water flow around the lower section of roots, have water in the system in timed intervals, “mist” the roots with a combination of air and water, or have air rising through the solution (oxygenating the water). Other factors must also be considered. First, the water needs to be free of any bacteria and funguses which would thrive in this setting. Secondly, the water needs to be about room temperature for optimal absorption. Thirdly, the solution needs to effectively distribute the minerals; this can be through the rate of flowing water, or agitation of static water.

Diagram of a fogponics system in which the roots are exposed to a very fine mist of nutrient solution.

 

Although, they are not required for a hydroponics system, many arrangements take advantage of a grow light and/or added extra carbon dioxide.

 

The true value of hydroponics is when soil is a rare resource. This is hard to imagine, but, outer space or remote, rocky islands are a perfect example. NASA is one of the foremost researchers in the field. Unfortunately, hydroponics systems can be very delicate to set up and grow; specifically in ways where a traditional soil bound plant would be more resilient. Many soil types absorb water and help to weed out fungus and bacteria. When the roots of a plant are surrounded by a warm, humid environment it becomes a significantly better for unwanted bacteria and fungus to thrive. Lastly, another downside is cost; hydroponics systems don’t have to be expensive, but, they will typically be more than a soil/ground based pot or garden.


 

 

Resources

 

http://www.hydroponics.name/

 

http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm

 

http://topshelfproduce.com/store/index.php?main_page=index&manufacturers_id=45

 

http://www.hydroponicsfarming.com/Hydroponics-Information.html

 

www.core77.com

 

http://www.bghydro.com/

 

http://edis.ifas.ufl.edu/cv216

 

www.core77.com