Conditioning Water: Hydroponics

Nathania Nischal

IntroductionHydroponics is a growing industry that involves growing plants not in soil, but in water. In a hydroponic system, many plants are put in pots called net pots, placed in a growing medium like clay pellets or rockwool that help keep the plants in place, and are then submerged into water that contains a nutrient solution. Hydroponically grown crops tend to grow a lot faster than growing plants in soil, and almost any plant can be grown this way in any quantity. However, the harvest will only be bountiful if the water conditions are good. In this project, different water conditions are tested to see which is ideal for hydroponically growing mint. The average nutrient solution ratio for mint is 24:8:16, 24 being nitrogen, 8 being phosphorus, and 16 being potassium, used for the control and “Normal Minerals” in this project. The pH that mint grows well in is anywhere from 5.5 to 6.5. This range will be used for control and “normal pH.” Some solutions will have a higher pH, higher concentration of minerals, lower pH, and a lower concentration of minerals. One solution will be the control.

PurposeThe purpose of this project is to find out if changing the pH of the water plants are growing in or changing the amount of essential nutrients affects the plants more.

ProblemWill changing the pH of the solution plants are growing in or changing the amount of nutrients affect the plant more?

HypothesisIf the nutrients in the water are increased , then the solution the plant is in will become much more concentrated to the point of becoming hypertonic, therefore the plant’s cells will shrivel up, causing the plant to die quickly.

VariablesIndependent Variables: solution to grow plants

Dependent Variables: Growth and condition of plant

Constants: Amount of water, type of plant grown, area grown, method used to grow plants, size of pot grown in, amount of growstones, amount of sunlight

Control Group: Container which has normal tap water pH and the normal nutrient solution.

Materials● 75 ml calcium nitrate (CaNO3)● 5 5 gallon buckets with lids● 1 air pump with 6 valves● 50 ml potassium sulfate (K2SO4)● 94 l distilled water (25 gallons)● aqualine tubing● 25 ml magnesium sulfate (MgSO4)(epsom salt can be substituted)● 30 ml monopotassium phosphate (KH2PO4) ● 5 net pots● 5 air stones● pH strips● pH up● pH down● 75 ml + vinegar● 75 ml + baking soda

Materials Cont’d● mint plants● cutting tools● disposable cups● burnt clay pellets● 4 ft led light

Procedures1. Cut 1 hole in each lid, just large enough to place a small net pot in each one.2. Cut a small hole in the side of each bucket, just large enough to pass the tubing through it. Run about a meter-long segment of tubing through each hole. 3. Hang the light above the buckets.4. Place an airstone in each container, and attach the tubing to it. attach the free end of the tubing to an air pump.5. Pour 18.5 L (4.9 gallons) of water in each container.6. In 4 separate cups, mix 4 solutions, each with 5 ml KH2PO4, 15 ml CaNO3, 10 ml K2SO4, and 5 ml MgSO4. In one of the mixtures, add an extra 5 ml of KH2PO4, 15 ml

CaNO3, 10 ml K2SO4, and 5 ml MgSo4. 7. In another cup, mix 2.5 ml KH2PO4, 7.5 ml CaNO3, 5 ml K2SO4, and 2.5 ml MgSO4.8. Pour each mixture into a separate bucket, turning on the air pump so that the solution will dissolve. Mark each bucket so that you know which bucket contains which

solution.9. Using pH strips, measure the pH of the water. Make sure that in all the buckets, the pH is around 5.5 - 6. If the pH is too high, and pH down until desired pH is reached. If

too low, add pH up until desired pH is reached. 10. In one of the buckets with a normal solution, add 75 ml vinegar and check the pH. If the pH isn’t 3, keep adding vinegar until it reaches the desired pH.

Procedures Cont’d11. In another bucket with a normal solution, add 75 ml baking soda or more until the pH of 8 is reached.

12. Clean clay pellets by letting them soak in water for a little bit.

13. Place healthy mint plants that are all about 5 cm tall and with roots about 2 cm long in the net pots, using clay pellets to hold the plant in place. Once the plants are in place, use the rest of the clay pellets to fill the net pots.

14. Place lids on each bucket, and put a net pot in each hole.

15. Observe plants for 2 or more weeks, measuring root length, plant height, and any changes.

Pictures

Data Tablessolution type plant height day 1 plant height day 7 plant height day 15 plant height day 19 total

average growth per day

control 5.3 5.9 6.1 6.5 1.2 0.06

increased minerals 5.5 4.3 4.3 4.3 -1.2 0

decreased minerals 6 6.2 6.3 7.1 1.1 0.05

high pH 5.8 5.9 6 6 0.2 0.01

low pH 5.4 5.6 5.7 5.7 0.3 0.02

average 5.6 5.58 5.68 5.92 0.32 0.028

Data Tables COnt’dsolution type root length day 1 root length day 7 root length day 19 total growth

average growth per day

control 2.6 2.8 4.7 2.1 0.11

increased minerals 2.2 2.2 2.2 0 0

decreased minerals 2.3 2.4 4.2 2.1 0.11

high pH 2.1 2.2 2.3 1.2 0.06

low pH 1.9 2.1 2.2 1.2 0.06

Average 2.22 2.34 3.12 1.32 0.068

Graphs

Graphs

Analysis All the plants fared well at first. The plant that was in the solution with more nutrients started to dry up within three days, however. It died within five days. The plant with the lower pH started browning at the ends of its leaves after the first week. The plant in the high pH solution had most leaves starting to brown after nine days. The plants with the normal solution and the one with the decreased nutrients remained healthy looking throughout the experiment, showing only a little browning on one or two leaves, but were otherwise green and healthy. The control plant grew 1.2 cm. The plant with more minerals didn’t grow at all, and as a result of shriveling, it shrank in height. The plant with decreased minerals grew 1.1 centimeters. The plant with higher pH grew 0.2 cm. The plant in the lower pH solution grew 0.3 centimeters. The control plant grew The plant with the increased minerals died due to the high concentration of minerals in the water, which created a hypertonic solution. The hypertonic solution caused the cells to shrivel up, making the plant as a whole shrivel up and die.

ConclusionSolutions with more nutrients may be harmful to plant, because of the high concentration of the solution in the water. This causes the plant to be in a hypertonic

solution, causing the plant to take in more solution and pushing out more water, which causes cells to shrivel up and die. Solutions with higher or lower pH may also harm the plant. Solutions with a higher pH may block the plant from getting nutrients like phosphorus, and a lower pH may block the plant from getting nitrogen, potassium, sulfur, and magnesium. Solutions with a lowered amount of minerals is safe, because the plants don’t risk over fertilizing or the pH changing to much. Having a normal amount of minerals and a normal pH is safe as well.

Further Research and APPLICATIONSHydroponics allows plants to be grown without soil. This means that people who live in places with poor soil or have no soil can grow things. Also, hydroponics are

very effective. Although the cost for building a large hydroponics garden may be expensive, if you mass produce expensive vegetables, your cost would be worth it. Plants tend to grow faster during hydroponics than in soil, so you can grow more crops, faster. This creates an opportunity for many to grow and sell crops. Plants can also be grown indoors, as long as they are provided with good lighting. Also, the plants grow in a more sterile environment than plants in soil do. They don’t require pesticides or fertilizers. They can also be grown all year long.

Hydroponics dates back to the 1600s, but the concept of growing plants without soil began long before that, at around the time of ancient Egypt. People believe that hydroponics was used to grow the plants in the Hanging Gardens of Babylon. The Aztecs had floating gardens because they had no land to grow crops in. The roots would be submerged in the water, underneath rafts of reed that never sank. Marco Polo described floating rice gardens of the Chinese. Ancient hieroglyphics show plants growing on the nile without soil. In 1699, a scientist tried growing plants in water with a very small amount of different types of soil, which acted as nutrients for the plants. Many after picked up on this idea, and hydroponics evolved into what it is today.

References● Hydroponics Lab Report (Date unknown). Retrieved September 31, 2015 from http://teamsciencerocks.weebly.com/hydroponics-lab-report.

html

● Potassium for Crop Production (2015). Retrieved October 15, 2015 from http://www.extension.umn.edu/agriculture/nutrient-

management/potassium/potassium-for-crop-production/

● Understanding Nitrogen in Soils (2015). Retrieved October 15, 2015 from http://www.extension.umn.edu/agriculture/nutrient-

management/nitrogen/understanding-nitrogen-in-soils/index.html

● The Nature of Phosphorus in Soils (2015). Retrieved October 15, 2015 from http://www.extension.umn.edu/agriculture/nutrient-

management/phosphorus/the-nature-of-phosphorus/index.html

● Winterborne, Jeffery. (2005). Hydroponics: Indoor Horticulture. England : Pukka Press LTD

● Barker, Allen V. & Pilbeam, David J. Handbook of Plant Nutrition: Second Edition. Massachusetts: CRC Press

AcknowledgementsI would like to thank my mother for giving me the idea to grow mint plants, and my dad for helping me with cutting the buckets and

setting up the hydroponics system.