Plant Growth in Aquaponic System through Comparison of Different ...

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Figure 1 – NFT System Utilized at Lynchburg Grows in Lynchburg, Virginia. Water from the bottom trough is pumped up to the upper two levels, where a thin layer of water flows down and returns back to the bottom trough on the opposite side. Another aquaponics variation is the floating raft technique (Figure 2). This system requires troughs with a minimum of a foot of water. A “raft”-like structure containing individual pots with the designated media float on the water so roots grow directly into the water. Seedlings can be started in pots out of the system and after they germinated, are placed in the raft’s net pots or started directly in the rafts in the troughs. This system provides maximum exposure of roots to the nutrient-filled water. This system is ideal for cultivation of leafy greens or other types of vegetables (Rakocy et al., 2006). This system does leave roots vulnerable to damage by aquatic organisms, such as zooplankton or bacteria (Rakocy et al., 2006). Figure 2 – Floating Raft System Utilized at Lynchburg Grows in Lynchburg, Virginia. The water from the bottom trough is pumped up to the upper troughs through a pipe. The water enters at one corner and drains out of the opposite corner.
There are many different medias in which to grow plants, and each has advantages and disadvantages. The medias used in this experiment were gravel, soil, and coconut fiber. Gravel has a large surface area for bacteria to grow and perform nitrification. Also, the composition the gravel itself can provide some nutrients for plants as the water weathers the rock, for example calcium can be released as the gravel reacts with acid produced during nitrification (Rakocy et al., 2006). A disadvantage is that the gravel retains very little water. Soil has the ability to supply the plants with enough water without becoming overly saturated. Because soil is composed of smaller grain sizes compared to gravel, it is able to retain some water while the excess drains out. There are also pore spaces that provide the plant roots with air (McCauley et al., 2005). Soil naturally contains nutrients, but does not always contain enough for healthy plant growth and it can be depleted of nutrients as the plant grows. Coconut fiber is made from the husk of a coconut. It is highly absorbent material but it does not contain abundant nutrients. The different medias provide surface area for bacteria to grow and perform nitrification, and capture solids before they reach the plant roots (Rakocy et al., 2006). A good medium for plant growth creates a nutrient pool around the plant roots and provides adequate air space for respiration (Sikawa, 2010). There are a total of 18 essential nutrients for maximum plant growth. The three macronutrients are carbon, oxygen, and hydrogen, which are supplied by the water and carbon dioxide gas. Other macronutrients provided by the nutrient filled water include nitrogen, potassium, calcium, magnesium, phosphorus, and sulfur. The remaining nutrients are micronutrients. A balance of all these nutrients provides for optimal plant growth (Rakocy et al., 2006).
Page 1 and 2: Plant Growth in Aquaponic System th
Page 3: minimizing nutrient inputs and the
Page 7 and 8: Figure 4 - Lettuce plant grown in t
Page 9 and 10: number that corresponded to a pot o
Page 11 and 12: of this time difference, because it
Page 13 and 14: height (cm) height (cm) 25 20 15 10
Page 15 and 16: Table 1- Average biomass for radish
Page 17 and 18: along with plants grown in gravel a
Page 19 and 20: soil and lettuce grown in coconut f
Page 21 and 22: into the water, providing the plant
Page 23: References Denckia, T.L.K. (2003).

Plant Growth in Aquaponic System through Comparison of Different ...

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