Hydroponics

Hydroponics can be defined as the cultivation of plants in water without soil.

An Introduction

Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, expanded clayor coconut husk.

Researchers discovered in the 18th century that plants absorb essential mineral nutrients as inorganic ions in water.

In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant’s water supply artificially, soil is no longer required for the plant to thrive. Almost any terrestrial plant will grow with hydroponics. Hydroponics is also a standard technique in biology research and teaching.

Why Hydroponics?

Growers all over the world use hydroponics because of the lack of large water supply or fertile farmland. Hydroponics is also used by home gardeners, on a smaller scales, because this method permits them to grow fresh vegetables year round and grow plants in small spaces such as balconies or in their garage.

• Soilless gardening offers many advantages to the gardener. There are no weeds to remove, and soil-borne pests and diseases are minimized, if not eliminated.
• If grown properly, hydroponic plants are also healthier and more vigorous.
• There is the advantage that the entire system may be automated with a timer.

Cultivating plants without soil eliminates the need for vast farmland and allows crops to be produced in greenhouses or even desert lands. Actually, this is why we consider Hydroponics to be a feasible method to grow crops on Mars.

Hydroponic techniques also allow for precise water and nutrient application directly yo the roots of each plant. Water is reused in these systems and less is lost through evaporation and run-off. Therefore, arid lands can be transformed into productive lands using limited amount of water.

Hydroponics in not difficult, as long as plant growth requirements are met, there are numerous hydroponic systems that can be used.

Types of Systems

Water Culture Systems

The nutrient film technique is one water culture system. It consists of a plastic tube as the container through which a constant,thin film of nutrient solution flows. Plants are suspended through holes in the top of the tube. The tube is gently sloped so gravity pulls the  solution back to the nutrient reservoir.

The aeration method uses an aquarium air pump to bubble oxygen to the roots of plants immersed in the nutrient solution. Plants are suspended 1 inch above the solution by a 2-inch-deep mesh tray that is set into the container by placing the lip of the tray over the container’s edge.

Aggregate Systems

Aggregate Systems use some form of inert material to support and surround plant roots. The most common materials used are rockwool, clay pebbles, gravel, perlite, vermiculite, sand, or foam chips. The media provides plant support, allows good oxygen penetration to the roots, yet retains a thin layer of nutrients and water around the roots.

One of the most hydroponic setups using an aggregate media is the Flood and Drain Method.  A water-holding container, such as a plastic dish pan, is filled with the aggregate and plants. The container is flooded periodically with the nutrient solution. The solution is drained back into the nutrient reservoir by opening a valve at the bottom of the container. During each cycle, the roots should be submerged in the solution for no more than 20 to 30 minutes.

Another common hydroponics setup is the Trickle Feed Method. The nutrient solution is continuously pumped from the reservoir through a 1/2-inch irrigation tube that branches into a number of 1/8-inch tubes. These smaller tubes deliver the solution to the containers. Any excess solution is collected at the base of each container and returned to the nutrient reservoir.

Alternatives?

Hydroponics is not the only alternative growing method.

Aeroponics is very similar to hydroponics; it is a Nutrient Film Technique. It is the growing of plants in a container in which the roots are suspended in a nutrient mist rather than in a solution. The most popular container for aeroponics is an enclosed A-frame constructed of styrofoam boards. The plants are placed in holes along the sloped sides of the frame. The nutrient mist is delivered to the roots by a vaporizer or by special attachments available with drip irrigation kits. The mist clings to the roots. Any excess runs down the inside of the frame, is collected at the bottom, and is recycled back to the nutrient reservoir.

The Nutrient Solution

Jipipe Solution 2.4 Kg
Nitrogen	10%
Phosphorus	6%
Potassium	12.5%
Calcium	9.4%
Sulfur	3.4%
Magnesium	2.2%
Boron	0.02%
Zinc	0.003%
Copper	0.002%
Manganese	0.03%
Iron	0.002%

Support Media

For the support media we used what are called grow bags. Grow Bags are a low-cost alternative to plastic pots. Manufactured from virgin polyethylene material, with three-layer co-extruded construction for strength, durability and long-lasting use. Prepunched with drain holes (if not drain holes would have to be made), these bags stand up easily when filled with growing media. Ideal for use with drip irrigation systems.

Growing Medium

Soil is never used in hydroponic growing. Some systems have the ability to support the growing plants, allowing the bare roots to have maximum exposure to the nutrient solution. In other systems, the roots are supported by a growing medium. Some types of media also aid in moisture and nutrient retention. Different media are better suited to specific plants and systems. It is best to research all of your options and to get some recommendations for systems and media before making investing in or building an operation. Popular growing media include:

• Composted bark. It is usually organic and can be used for seed germination.
• Expanded clay. Pellets are baked in a very hot oven, which causes them to expand, creating a porous end product.
• Gravel. Any type can be used. However, gravel can add minerals to nutrient. Always make sure it is clean.
• Oasis. This artificial, foam-based material is commonly known from its use as an arrangement base in the floral industry.
• Peat moss. This medium is carbonized and compressed vegetable matter that has been partially decomposed.
• Perlite. Volcanic glass is mined from lava flows and heated in furnaces to a high temperature, causing the small amount of moisture inside to expand. This converts the hard glass into small, sponge-like kernels.
• Pumice. This is a glassy material that is formed by volcanic activity. Pumice is lightweight due to its large number of cavities produced by the expulsion of water vapor at a high temperature as lava surfaces.
• Rockwool. This is created by melting rock at a high temperature and then spinning it into fibers.
• Sand. This medium varies in composition and is usually used in conjunction with another medium.
• Vermiculite. Similar to perlite except that it has a relatively high cation exchange capacity–meaning it can hold nutrients for later use.

The specific grow bags we started off using look like the one underneath. It has all the characteristics mentioned above, but the difference with the traditional grow bags is because of the growing media. The filling is coconut peat. (We call this growing bags Bolis) At first they are pretty much flat, but as you add water, they grow to the size needed for planting.

The growing bags need a support. This support has to be the same length as the Boli, and a well-built structure that gives stability for the bags. The ideal design is one that has a good drain, so the solution can leave the Boli after the plants are watered. The draining is necessary because the roots are not supposed to be in contact with the nutrient solution the whole time, so this way, the solution can flow out. This is the design we decided to use for our strawberry plants.

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References used

Hydroponics:  http://en.wikipedia.org/wiki/Hydroponics

Soreson, Ruth and Diane Relf. “Home Hydroponics” Virginia Cooperative Extension. Viginia: Publication 426-084

http://www.cosechandonatural.com.mx/solucion_jipie_ctpr23_44.html

https://www.growerssupply.com/farm/supplies/Search?searchMethod=wcSearch&searchType=ANY&searchQuery=grow+bags

http://www.growingedge.com/basics/growingtips.html#growmedium

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