A Comparative Analysis of Two Plant Growth Mediums ...

[Pages:27]Running Head: HYDROPONICS VS. SOIL

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A Comparative Analysis of Two Plant Growth Mediums: Hydroponic vs. Soil Maeva Makendi S.G

The Academy of Science, Research and Medicine at THE Paulding County High School

Running Head: HYDROPONICS VS. SOIL

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Table of Contents

Table of Contents.............................................................................. 2

Abstract.......................................................................................... 3

Introduction..................................................................................... 4-7

Methods & Materials...........................................................................8-10

Results............................................................................................11-20

Discussions...................................................................................... 21-24

References........................................................................................25

Appendix.........................................................................................26-27

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Abstract

Plants do not need soil in order to grow and survive. Soil act as a medium for plant to help support it and to retain nutrients. However, any medium that is stable enough to support plant and can retain nutrients can do the same job as soil without being restricted to the ground. This is where hydroponics comes in; hydroponic is a method of growing plants using mineral solution, in water, without soil. This method can be extremely helpful to countries that have poor land, which is not able to sustain agriculture. The purpose of this lab is to prove that hydroponic horticulture can be just as effective if not better than plants traditionally grown in soil. The hypothesis goes like this if the hydroponic plants and plants grown in soil are given the same germinating and growing conditions, then the hydroponic plants will do as well if not even better than the plants grown in soil. This experience was conducted using an assortment of fruit, vegetables and herbs. Half the seeds where grown hydroponically, while the other half was grown in soil; both were kept in the same conditions, in order to not alter the experiment in favor of one or the other. The plants were grown for thirty days, in order to ensure accurate results. After a month the stated hypothesis was proven correct, the hydroponic and soil plants grew almost the same, with the hydroponic plants germinating faster and growing faster than the soil plants.

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Introduction

Often time when learning about plants, we stumble unto the basic so called necessities of plants, the big four as some call it, sun, soil, oxygen and water. Three out of the four basic necessities given are true. Plants are autotrophs that make their own food using the sun using a process called photosynthesis. The word photosynthesis means to put together with light and this is exactly what occurs. It occurs in the chloroplasts of plants. This process is limited to the supply of light, water and carbon dioxide. Limiting any one of the factors on the left can greatly impact the amount of photosynthesis produced. During the process of photosynthesis electrons are boosted up by the energy from the sunlight. The chloroplast uses these electrons, along with the carbon dioxide and hydrogen ions, to produce sugar molecules (Campbell et al., 2009). The reaction steps add up to the following photosynthetic equation:

Photosynthesis occurs in two stages, the light dependent reaction and the Calvin cycle, both with their own individual steps. In the light reaction the energy in sunlight is converted to chemical energy. The reaction relies on molecules built in the membranes of thylakoids. First, light energy is captured by the chlorophyll molecules in membranes. Then the captured energy is used by the thylakoid to remove electrons from water. This divides the water into oxygen and hydrogen ions. This are considered waste products and are used to make NADPH. The captured energy is also used to generate ATP. The Calvin cycle makes sugar from the atoms in carbon dioxide including

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the hydrogen ions and electrons carried in NADPH. The ATP made in the light reaction provides the energy needed to make to sugar. The Calvin cycle is known as the "light independent reaction" because it does not need light to begin. However, it does need ATP and NADPH which comes from the light cycle (Williamson et al. 2009). It is obvious to see that the sun or light is an important contributor to plant growth and development.

The fact that plants need oxygen is unarguable. This is because all cells not just plant cells need oxygen to perform aerobic respiration. Respiration is the process of breaking down food to get energy. The cells in the green part of plants where photosynthesis is occurring get the oxygen they need from the oxygen produced by photosynthesis. This means that the cells in the leaves and stems of the plants are getting adequate requirements. The problem comes from the cells in the roots of the plants, where there is no photosynthesis occurring due to the lack of light. In the majority of plants this cells get their oxygen from air in the spaces between the dirt particles in the soil. "All living things combine food with oxygen to attain energy. Plants are no exception. They make food and combine it with oxygen in order to release energy for themselves. On the contrary, during day time, plants release lots of oxygen in the air because while making food during photosynthesis, they change carbon dioxide and water into food and oxygen. But, at the night time, just like other living beings, plants absorb oxygen to breath" (Insaan, n.d.). If the plants have no access to oxygen there would not be any respiration and the plant would not be able to function. Due to the lack of oxygen the roots will not be able to grow to take in water, which would cut off the nutrients needed for the plants to grow and survive.

Plants need water to grow. One of the major factors driving water movement in plants is transpiration. Transpiration is the loss of water from plants in the form of vapor (evaporation). Plants use 95% of the water absorbed from soil for transpiration, 5% is used during

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photosynthesis for the production of carbohydrates necessary for plant growth (Whiting et al,.). The growth of plants is dramatically affected by the amount and timing of water applied during its production. Different stages of plant growth are more sensitive to water stress than others. The ability of plants to resist stress from insects and/or disease is influenced by water. If plants do not have water, they would die, because they are missing one of the main components needed to ensure the efficacy of their growth.

While researching the necessities for plant growth, there was no suitable reason given for why plants need soil to grow. The reason for this is because they do not. The purpose of plants is to anchor plant roots and act as a source of water and nutrients needed for healthy growth. However, couldn't any medium capable of retaining water and nutrients do the same job as soil? Technically speaking soil is just a glorified medium, and any substance with high absorbency materials could do the same job.

Hydroponic is a method of growing plants using mineral solution, in water, without soil. In the 18th century researchers discovered that plans absorb essential nutrients as inorganic ions in water. The soil acts as a mineral nutrient reservoir but the soil is not essential to the plant growth. When the mineral nutrients in soil are dissolved, plant roots are capable of absorbing them. When the mineral nutrients are artificially introduced into a plants water supply soil is no longer needed for the plant to become successful. This are not just for some plants, almost all terrestrial plants will grow with hydroponics. This is the key. Hydroponics allows the grower several advantages compared to soil. It allows the grower to control the nutrition levels in the reservoir which allows for lower nutrition requirements, the water remains in the system and can be reused, which lower the amount the water required. There is no nutrition pollution being released in the environment because it is in a controlled system. It allows for stable to high

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yields, diseases and pest are easier to get rid of than in soil because the system can be mobile, it is easy to harvest and there is no pesticides damage. The most important advantage of hydroponics is that it uses less water than soil and that it can be used in places where in-ground agriculture or gardening are not possible.

This is extremely relevant when applied to current global conditions. 71% of the Earth is made up from water but only 3% is freshwater needed for human use. Places in some parts of the Middle East are dry, desolate places lacking any vegetation because the land is not suitable for agriculture, due to the lack of rainfall and human activities. Hydroponics can help produce crops suitable for human consumption and already have. Countries such as Israel have implemented hydroponic techniques with great success. NASA has been trying to develop hydroponic system that can be used in space. This will allow fresh plants to be grown in space stations. Hydroponics is the perfect solution because it uses less water than soil grown plant and it can be grown virtually everywhere. Regions with poor soil conditions will no longer be dependent on exports from other countries. Not only will hydroponics help reduce the amount of water wasted per year due to poor irrigation of the soil, but it provides a solution to those country who struggle because of the inability to produce their own crops.

It is not that hard to see that plants do perfectly fine without soil and in fact can thrive without it. Plants need oxygen, nutrients, water and sun. The purpose of this lab is to prove that hydroponic horticulture can be just as effective if not better than plants traditionally grown in soil. The hypothesis goes like this if the hydroponic plants and plants grown in soil are given the same germinating and growing conditions, then the hydroponic plants will do as well if not even better than the plants grown in soil.

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Methods & Materials This experiment could easily be replicated by anyone looking to test and compare plants grown hydroponically and those that are grown in soil. In order to replicate this experiment the person would need to gather the material needed (Al 1) and carefully follow the procedures indicated below. The person would need seeds from varying plants fruits, vegetables and herbs. For this large experiment the seeds used were brand name spinach and generic spinach seeds, basil, watermelon, lettuce, parley, habanero peppers, French onions, carrot and kale. To duplicate this experiment on a smaller scale a person would need kale or spinach, watermelon, and parsley or basil. This is because the seeds stated germinate quickly to expedite the experiment. The varying seeds would give us an accurate result of the hydroponics and soil plants efficacy among different vegetation. Six used ice cream containers were used as containers for the hydroponics. They were covered in black plastic bags so as to not let the sunlight penetrate through them, because this will cause algae to grow inside the reservoir affectively ruining the experiment and not allowing the hydroponics to grow. Five holes, each one and half inch in diameter were carved into the lids. The ice cream lid should look approximately like the diagram shown below:

The holes cut into the lids were slightly smaller than the net pots, so that they do not fall through. Net pots are containers like items, used to hold the hydroponics inside of them. They keep the plants supported on the lids; when considering purchasing them, make sure that the lips of the net pots are larger than the net pots itself, this allows the net pots to have a "grip" when

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