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Growing Plants 1Growing Plants via Hydroponics BySandra Cash & Hannah Peterson Dr. Thomas Crown College General Biology, Section 112 30 April 2012
Growing Plants 2 Abstract This article first defines hydroponics and relates the history of hydroponics. Secondly, this articledescribes the various methods of hydroponics. Next, this article talks about a few of the problemshydroponics has compared to problems with cultivation in soil. Then, it goes over Sandra Cash’s andHannah Peterson’s experiment to determine which method of growing plants is better, hydroponics orsoil. Lastly, it goes on to talk about the results Sandra Cash and Hannah Peterson found through theirexperiment.
Growing Plants 3 Hydroponics is the method of growing non-aquatic plants, in a reservoir of water using anutrient solution that is added to the water to encourage plant growth. This is advantageous for growingcrops out of season in a green house. The hypothesis of this experiment was that plants would growbetter in hydroponics than in normal soil conditions because of the ability to control the amount ofnutrients the plants receive. According to the University of Arizona in a study of the growth of tomatoesin hydroponics: “The development of hydroponics has not been rapid. In the U.S., interest began to develop in the possible use of complete nutrient solutions about 1925. [Because] Greenhouse soils had to be replaced at frequent intervals or be maintained from year to year by adding large quantities of commercial fertilizers. As a result of these difficulties, research workers in certain U.S. agricultural experiment stations turned to nutrient solution culture methods as a means of replacing the natural soil system with either an aerated nutrient solution or an artificial soil composed of chemically inert aggregates moistened with nutrient solutions” (Hayden). Hydroponics is a subset of hydro culture and is a method of growing non-aquatic plants, usingmineral nutrient solutions, in water, without soil. In certain situations it can be more effective to growplants in hydroponics then in regular soil because you can then control what kind and how much of thenutrient solution to add to the water. The experiment was to discern whether Purple Daisies,Osteospermum, would grow better in a hydroponics kit then in regular soil conditions. According tostudies completed by institutions such as the Delaware Valley College; “Hydroponics is the scientific frontier of agriculture, which sustains human life on Earth. The challenge is to meet the world’s food needs while preserving Earth’s natural resources. At the same time as we are concerned with hydroponic food production on Earth, the US National Aeronautics and Space Administration is also committed to this new technology to cultivate
Growing Plants 4 crops in space, which is vital to human exploration of the Moon and Mars” ("Delaware valley college," 2011).Hydroponics is an alternative for plant growth, but it is not without its own drawbacks. Withhydroponics, there is the possibility that the plants can contract disease such as Pythiumaphanidermatum, a water mold that infects young plants and slowly kills them. It is increasingly difficultfor those that work in greenhouses, because it favors warm and damp conditions (Parker). DoctorTimothy Shelford at Cornell University has studied some risks of growing plants in hydroponics: “Pythium aphanidermatum has been identified as the main obstacle/risk in the production of hydroponically grown baby leaf spinach. This organism is so prevalent that even crops grown in fresh nutrient solution will often show signs of Pythium damage at harvest time” (Shelford, 2010). Before starting this experiment, the hypothesis was that the purple daisies would grow betterand faster in the hydroponics kit since it allowed for the control of nutrients and therefore control of thegrowing conditions. Twelve individual daisies were grown, six in regular soil and six in the hydroponicskit and all were monitored over two months. A container holds about six gallons of water with two teaspoons of nutrient solution for everygallon of water. Six plant containers are placed down in the nutrient solution. An aquarium air pumpconstantly bubbles in the nutrient solution, keeping the plants’ roots from drowning. Clay pellets fill theplanters and allow the water to reach the plants without the plants being so deep in the planter so thatsunlight cannot reach them. Aside from the planters, the rest of the container is covered to block the nutrient solution frombeing exposed to sunlight; this is to ensure that algae does not begin to grow in the hydroponics kit.
Growing Plants 5During the course of the experiment, seeds were first kept watered and under artificial lights tostimulate growth, after the roots became large enough to support themselves all twelve plants weremoved into larger planters and the plants going into the hydroponics kit were totally removed from soil. After one week in the new planters, the soil grown plants began to look healthier then thehydroponics plants. After two more weeks the soil plants continued to look healthier than thehydroponics plants, but watering for the soil plants was increased from 50 ml to 60 ml. After threeweeks, the soil plants continued to improve, though plants did not appear to be as large as they should.The plants in the hydroponics kit still looked unhealthy, especially the three farthest from the sunlight.The water in the hydroponics kit was quickly changed, and three teaspoons for every gallon of waterwas added to the nutrient solution to encourage plant growth. Two weeks later showed continued improvement with most of the soil plants, but three werewithered and dead looking. The water level in the hydroponics kit was low, so about 50 ml of water wasadded directly to each plant. The three plants farthest from the sunlight were dead. These experimentstook place in the Chemistry lab in Crown College from February 21, through April 17, 2012. Results of this experiment were inconclusive and more data is needed to make an informedconclusion. Half of the hydroponics plants died due to the lack of sunlight, since the planters shadedthem. The three hydroponics plants that did survive grew extremely slow, to about one inch in length.The soil plants did better, although half of them also died due to unknown reasons. The surviving soilplants grew faster and developed multiple stems and leaves. The soil plants grew to about three to fourinches, and looked healthier than the plants in the hydroponics kit.
Growing Plants 6The results of the experiment could have been affected by the two weeks needed for the hydroponicskit to be shipped from the company, and another two weeks for the setup of the kit. All results werebased on a month given to the growth of the plants from the time available. Based on the results of thisone experiment it appears that hydroponics are not better for plant growth, but when data from otherexisting experiments is added, the results are more in favor for hydroponics depending on the type ofplants grown. Hydroponics is mostly used to grow crops such as lettuce, tomatoes, and other leafy greenplants (Schmidt). Flowering plants have been grown using hydroponics before, but it is much moredifficult and the time needed for growth is much longer. If the experiment is repeated it would be bestto try two or three species of plants for a variety and so that the results are not skewed in any way. Itwould also be prudent to allow more time for plant growth or to use faster growing plants. Pre-grownplants would be a way to examine whether or not hydroponics keeps the plants healthier than plants insoil conditions. It would also improve results if an artificial lighting system was set up above the plantsso that the results are not based on a differing amount of light each plant receives.
Growing Plants 7 Another way that could be used to improve the results would be to use a different hydroponicskit that would allow differences on how the water reservoir is used. There are five different types ofhydroponics kits available for commercial use at this time. According to professors at the University ofIllinois at Urbana-Champaign, there are four main systems that are effective for plant growth (Schmidt). The first is the simplest and probably the most well know method known as the water culture,reservoir method, and the aquaculture method. This method involves totally immersing the plant rootsin a nutrient solution mixed with a large amount of water. Next is the Aggregate Culture method that has the plant roots buried in sand or gravel and asupply of nutrients and water are added to the container when needed. This method is effectivebecause the sand/gravel support the roots. Aeroponics is another, more complicated way to growplants. This method has the roots totally exposed in an airtight container and constantly misted with anutrient/water solution. Lastly, there is the continuous flow system, which has the roots planted plastic piping, such aspolyvinyl chloride (PVC) pipe, commonly used for household waste plumbing, to allow a steady streamof nutrient/water solution to constantly flow over the roots. A water pump is connected to the pipe andto a large water tank, this allows the nutrient/water solution to be recycled and reused. In conclusion, hydroponics is a good alternative for soil grown plants when the hydroponics kit isused correctly and plants receive regular water/nutrient solution. While there are risks, they are lessobvious and there is less worry about parasites and diseases then with soil grown plants. Also, it isimportant that someone who is interested in growing plants in a hydroponics kit, research theinformation very carefully and totally before buying a kit. It is also important to know what species ofplants grow best in hydroponics conditions, and how they will respond to the various nutrient solutions.
Growing Plants 8ReferencesDelaware valley college. (2011). Retrieved from http://www.delval.edu/pages/nrbm/C1104/Hayden, A. N. (n.d.). hydroponic tomatoes. Retrieved from http://ag.arizona.edu/hydroponictomatoes/history.htmParker, K. (n.d.). Pythium aphanidermatum. Retrieved fromhttp://www.cals.ncsu.edu/course/pp728/Pythium/Pythium_aphanidermatum.htmlSchmidt, J. (n.d.). Hydroponic systems. Retrieved fromhttp://www.aces.uiuc.edu/vista/html_pubs/hydro/hydroponic.htmlShelford, T. (2010). The risk of pythium aphanidermatum in hydroponic baby-leaf spinach production. Retrieved from https://ecommons.library.cornell.edu/bitstream/1813/17229/1/Shelford, Timothy.pdf