Emily Robb
Age 16 | Brandon, Manitoba
Canada-Wide Science Fair 2019 Excellence Award: Senior Gold Medal | Nutrients for Life Foundation Award | Youth Science Canada Environment Challenge Award | $4000 Western University Entrance Scholarship
doi: 10.18192/csfj.v2i320197479
In our growing world, the demand for food production is increasing at a rapid rate. By the year 2050, approximately nine billion people will need to be fed (Foley, J., n.d.), which is two billion people more than the worldwide population that we are currently struggling to feed. The agricultural industry needs to be encouraged to explore new directions regarding crop production. As a whole, the way that crops are currently being produced is not sustainable towards the future endeavours of agriculture, as well as the environment. Growing a crop with many beneficial properties under the influence of new methodologies can help to conquer the less than ideal food supply and security issues that we face today.
INTRODUCTION
Focusing on growing a crop as opposed to livestock requires much less time and biological energy expenditure, and may lead to solutions such as the quickly maturing and beneficial crop of arugula. Arugula contains 250mg/100g of nitrate which can assist in lowering blood pressure and enhancing athletic performance (Ware, M., 2017). It also contains compounds like sulforaphane which may have the ability to slow the growth and progression of cancer (Ware, M., 2017). Though this vegetable is low in calories, it is high in vitamins and minerals (Patil, K., 2019). When paired with being grown in a hydroponic setup (a system in which plants are grown without soil, only water), a sustainable alternative to conventional agriculture has been partially formulated. To further advance this alternative, the genetic potential of a plant could be assisted with a certain fertilizer so that it produces a larger yield, increasing the reliability of food security and the ideology of sustainable agriculture. The purpose of this project was to conduct an experiment that would determine if there was a specific concentration of a fertilizer brand that would allow arugula to produce significantly more biomass, or the total mass of these arugula plants, than what the other fertilizers could produce. I did this experiment with the nutritional content of the harvested plants in mind, because a high nutritional content, much like the quantity of food, is a very valuable asset for those who need to be fed. My experimental process involved selecting and testing three highly sought-after hydroponic fertilizer brands and used different concentrations of each, as well as a control, or baseline, of distilled water.
HYPOTHESIS
It was hypothesized that the highest concentration of a hydroponic fertilizer from a brand called General Hydroponics would statistically increase the biomass production of an arugula plant. This is due to the fact that the nitrogen content present in this fertilizer was high and it contained abundant micronutrients. Arugula consists of leafy foliage, which requires a substantial amount of nitrogen, or nitrate. A lack of nitrate would result in less foliage and thus less biomass. Based upon the guaranteed nutrient analysis of General Hydroponics, supposedly there were enough nutrients, specifically nitrogen, to promote luscious growth.
PROCEDURES AND MATERIALS
To begin conducting this experiment, I acquired a total of thirty Rubbermaid totes. This was decided because I would be testing ten different nutrient supplements, and running three trials, or repetitions, of each. The totes were situated in rows of ten, each row being spaced 15.24 centimeters apart. This was done so each tote could be individually accessed without disrupting another. Wooden planks were placed between the rows to offer support, and to provide consistent spacing of rows. The totes were packed tightly against each other so that, once filled with water, they could retain their shape better and have less outward bulge. Each tote corresponded with a lid, and each lid was drilled into with a 2¾” circular drill bit. The holes created would hold the pots that the plants would grow from. Each lid had six holes, evenly spaced apart to allow as much room as possible between them. The lids were labelled with a fertilizer concentration and brand. After randomly determining which fertilizers would be put in which tote (see Figure 2), the corresponding lid was placed in that location for the duration of the experiment. All light was then blocked off and lighting fixture consisting of 2 48-inch horticultural T12 bulbs each were hung from the ceiling. The lights were put on a 12-hour cycle to simulate nature with the help of an automatic timer. To actually house the plants that would be grown, 180 netted pots with a 3 inch, or 7.62 centimeter diameter were filled with medium grade vermiculite. Vermiculite is a brown mineral which can be used for insulation or as a medium for growing plants, specifically hydroponically. The vermiculite was not packed down and was filled to the same spot every time consistently. The pots were then set aside until the fertilizers were added. The totes were ready to be filled with water now. Exactly 63 litres of distilled water were measured out for every tote. Each tote needed to be aerated in order to keep the plants from drowning. Aquarium tubing was laid out and cut to specified lengths previously determined. Two hydroponic air pumps, each with six outlets, were the drivers of aeration. In order for the aeration to be consistent, two other totes were also added to this system with no plants growing in them. The way that the aeration was set up required two more totes, otherwise the distribution of air would be inconsistent. Figure 1 shows how the system was physically placed and where in relation it was compared to other objects. Figure 2 shows the basic setup of the totes, and how the aeration (blue) connected. The two black totes on the side are the ones where no plant growth occurred.
Figure 1. A view of the whole setup while arugula grows on day 35 of the experiment.
Figure 2. A basic diagram that shows the entire layout of the experiment from a bird’s eye view.
Nutrients could now be methodically measured out. A weak (2), a recommended (1), and a strong (3) concentration was made for each brand of fertilizer that I had. Concentration 2 meant dividing the recommended ratio by 2, and concentration 3 meant multiplying the recommended ratio by 1.5. Upon concentration measuring, fertilizers were mixed into their specified totes and were left until seed germination. Seeding this experiment involved sowing six arugula seeds into each pot of vermiculite. The six seeds could ensure a successful germination. Plants would be thinned if necessary. The pots were placed into the holes drilled into the lids, and the seeds became exposed to moisture which began germination. Pictures were taken of each test every day, and water samples were taken from each test every week. Water samples were frozen until testing which could correlate findings. Each plant was weighed individually after eight weeks of growth and was recorded for further analysis.
RESULTS
After sorting out the weights of each plant’s biomass into spreadsheets, I ran a function that would find the standard deviation between data values, which were the weights of each plant in grams, amongst each concentration.
Pictured in Figure 3 are the mean weights of plants for each concentration and brand of fertilizer tested, including the percent deviation shown as an error bar. This is a summarization of the individual weights recorded immediately after harvest. Percent deviations amongst all concentrations ranged from 24.25% to 69.90% (the majority remained below 40%), where the mean weights which correlated to each were also varied, being rather spaced out from each other. A deviation larger than approximately 30% indicated an unreliable and inconsistent yield, or not one that you would consider to be favorable. However, conclusions couldn’t be formed from this alone.
Figure 3. Mean weight of plants in each concentration and brand.
I then interpreted the biomass weight data values by placing them on a bell curve, as illustrated in Figure 4, to see how points were distributed. I found various skews, where nothing was a completely normal distribution, as well as a wide range of standard deviations, but this told me little about significant biomass production differences which I was attempting to find.
Figure 4. The normal distribution Excel formula value compared to plant weighs of Bumper Crop 2 in grams. The y-axis is a product of the function regarding the occurrence of weight data points.
To form conclusive evidence, I ran a large series of two sample t-tests for a mean (independent samples) to compare and contrast if the yields that correlated with a specific fertilizer were truly meaningful and had a statistically significant difference between each other. The summarization of the results of the t-tests is illustrated in Figure 5. A t-test is a type of statistical analysis that is used to determine if there is a significant difference between the means of two groups. It is a hypothesis testing tool, which allows testing of an assumption applicable to the specified test group by looking at a t-statistic, the t-distribution values, alpha values, and the degrees of freedom to determine what the probability of difference between two sets of data is with a t-value. A t-value provides a concise and clear answer as to whether or not a difference is statistically significant. In figure 5, µ represents the mean of a population, where 1 or 2 describes where they were placed in a t-test. HO means “null hypothesis” while HA means “alternate hypothesis”. The null hypothesis states that a difference in the independent variable(s) will not change the outcome, where the alternate hypothesis states that a difference will change the outcome. Like many, the goal of my experiment was to prove the null hypothesis to be false.
Figure 5. A summarization of t-test findings where µ1 is the vertical column and µ2 is the horizontal column, and statistically significant differences are displayed.
DISCUSSION
In Figure 3, disregarding the error bars, it is easily seen that the highest mean weight belongs to the dark blue column, or General Hydroponics 1 concentration. The least is easily depicted as well; the grey column representing the control of Distilled Water. This graph provides the best representation of the growth patterns that were achieved. Predominantly, it shows that more fertilizer is not better, and if anything, is the worst possible option to use when growing plants. In the Holland’s Secret and Bumper Crop brands especially, even a lesser concentration will give you similar results to a recommended concentration. In the General Hydroponics brand, the large gap separates the recommended concentration from the others tested, whereas the other brands have their larger gaps between the highest concentration and the others tested. The highest mean weight of harvested plants came from the recommended concentration of General Hydroponics.
The t-tests that compared the yields of various concentrations of the different fertilizers indicated that there were significant differences among the fertilizers. The fertilizer with the most statistically significant positive tests was the recommended concentration of General Hydroponics, where 6 tests created t-values which exceeded the p-value of 1.697 (found from an alpha value of 0.05 and a degrees of freedom of 34). The findings themselves don’t appear significant. However, the majority of the collected results can consistently be replicated. Some concentrations appear superior to all: General Hydroponics 1, Holland’s Secret 1, Holland’s Secret 2, and Bumper Crop 1. None of these concentrations had tests that proved them to be less significant than another. However, there was only one that had more positively significant tests than others, and that was the General Hydroponics 1 concentration. It tested to be insignificant compared to three other concentrations, which happened to be Holland’s Secret 1, Holland’s Secret 2, and Bumper Crop 1. Otherwise, a grey area was almost formed with other concentrations, until the most negatively significant concentrations began to show, which are Bumper Crop 3 and Distilled Water (more so Distilled Water due to the fact that there were no positive tests of significance that correlated with it). All mean weights recorded were less than General Hydroponics 1 by at least 10.77%. The water testing that was simultaneously taking place had been correlated to the depletion of biomass production in the high concentrations of fertilizer. The room for error in a hydroponic system is very small due to the fact that it is a closed system, which means that the threshold between lacking and exceeding nutrient recommendations is very small. This can lead to certain nutrients now being classified as toxic to the plants and causing substandard harvest weights.
Higher concentrations dehydrated plants quickly and stopped growth, as initial germination and growth was very quick and luscious, but it soon subsided as the recommended concentration consistently grew the whole time. Though other fertilizers proved to not be significantly different than the greatest producer, it has not been truly proven that they can produce more. Additionally, if a fertilizer is abundant in nutrients like nitrogen, it is more likely that they will grow so rapidly that the plant becomes stressed. The copious amounts of nearby nutrients, as observed when water samples were tested, allow the roots to barely develop, while the foliage thrives. Eventually, the small root system can no longer supply the plant with water and nutrients it needs, and the plant may become stunted in growth, grow slowly, or even die in extreme cases. This was observed in all high concentration tests from minimal to severe extents.
CONCLUSION
In conclusion, the hypothesis was incorrect, as the highest concentration of General Hydroponics did not produce the most biomass. In fact, the highest concentration of General Hydroponics was statistically worse than the concentration that produced the most biomass: General Hydroponics in the recommended ratio. The higher concentrations appeared to dehydrate all plants that it was exposed to, somewhat stunting growth. This demonstrates that offering plants ample nutrients won’t produce the best growth. Though it may appear that they are germinating/growing fast for the first while after seeding, it will prove to be short lived when the demands of the plant outgrow its capabilities. Therefore, with the data that I have collected and analyzed, it is reasonable to conclude that, statistically speaking, the General Hydroponics brand in a recommended concentration can efficiently form more biomass than other tested fertilizers, and can continually produce the most favored yield in relation to quantity/size.
APPLICATION
A wide variety of applicable scenarios now exist. The optimal fertilizer for a sustainable form of agriculture has been confirmed, thus enforcing an ideology that there is an optimal alternative to conventional agriculture. Now that a fertilizer has been found that produces more hydroponic harvest, it can become ideal for both commercial operations or home operations; both cash crop and self subsistence. If commercial operations used General Hydroponics brand with the recommended ratios of fertilizer, they’d produce a larger yield. The larger yield can in turn be used to increase the profit that they receive for growing crops. This heavily benefits the company in the long run due to the constant growing and selling of the large plants that they’ve grown. Consistently large plants being sold leads to a consistently larger profitability. A fertilizer that produces more food can now be used in relation to food banks and regions that suffer from food security crises. Everyone deserves to eat, and using practices that have an ideal fertilizer and growing method can result in a new standard of food security, a greater one that benefits more people. Food security is difficult to achieve, however, with these findings, we can begin to work towards a long-term alternative for food production. Having results that can be replicated proves that these conclusions can be used by commercial operations to work towards helping increase production and addressing the lack of food security that exists in our world. This project was designed with food security in mind because that itself is important. The results of this project can lead to working towards a greater future involving the topic of food security. Farming whilst using a closed system is highly sustainable as well. It is a closed and controlled system that cannot leach its nutrients into the surrounding environment which is one of the largest benefits to this project; heavily focusing on the topic of sustainability, as well as the environment. In using hydroponics to produce plants, I’m trying to enforce an ideology regarding the practices of sustainable agriculture. By using a hydroponic system, or systems, to produce food, I’m reducing the physical land that actually needs to be used and worked to farm. Farmland is often worked too much by machinery, and this often results in the erosion of topsoil. Continual working year after year results in continual erosion. Erosion degrades the environment and farmland that is utilized by avid farmers. Relating to this, hydroponics speeds up plant maturity, which is accelerating the natural growing process. It also keeps farmland from being over usage. An ideal fertilizer can form long-term alternatives to conventional agriculture. These results can help create more sustainable farming methods, as well as environmental protection, and a greater way of producing food for individual and mass consumption.
REFERENCES
Foley, J. (n.d.) “A Five-Step Plan to Feed the World”. National Geographic Magazine. Retrieved March 5, 2019, from https://www.nationalgeographic.com/foodfeature/feeding-9-billion-people/
Patil, K. (2019, March 4). “10 Interesting Benefits of Arugula (Eruca Sativa)”. Retrieved March 8, 2019, from https://www.organicfacts.net/health-benefits/vegetable/health-benefits-of-arugula.html
Ware, M. (2017, November 2). “Arugula: Health benefits, facts, and research”. Retrieved August 30, 2018, from https://www.medicalnewstoday.com/articles/282769.php
“2018 Global Report on Food Crises”. (2019). World Food Programme. Retrieved March 1, 2019, from https://www.wfp.org/content/global-report-food-crises-2018
Cassman, K. (2012, December). “What Do We Need To Know About Global Food Security?”. ResearchGate. Retrieved March 2, 2019, from https://www.researchgate.net/publication/ 257743286_What_do_we_need_to_know_about_global_food_security
“Definition and Dimensions of Food Security”. (2016, August 15). WOCATpedia. Retrieved March 1, 2019, from https://wocatpedia.net/wiki/Definition_and_Dimensions_of_ Food_Security
“Hydroponic Systems 101”. (n.d.). Fullbloom Hydroponics. Retrieved August 29, 2018, from https://www.fullbloomhydroponics.net/hydroponic-systems-101/
“What is Hydroponics?”. (2008). Simply Hydroponics and Organics. Retrieved August 29, 2018, from http://www.simplyhydro.com/whatis.htm
United Nations Environment Programme. (n.d.). “Sustainable Food Production”. UN Environment. Retrieved March 2, 2019, from https://www.unenvironment.org/regions/ asia-and-pacific/ regional-initiatives/supporting-resource-efficiency/sustainable-food
University of Alberta Office of Sustainability. (n.d.). “What is Sustainability?”. University of Alberta. Retrieved March 9, 2019, from https://www.ualberta.ca/sustainability/ Resources/~/media/sustainability/Resources/Green%20Guide/Documents/What-is-Sustainability.pdf
Emily Robb
Emily Robb is a grade 10 attending Vincent Massey High School in Brandon, Manitoba. With subjects such as botany, horticulture, plant pathology, agriculture, and environmental stewardship (sustainability) sparking her interest, hobbies involving horticultural experimentation and working with agricultural matters are a result. Heavily involved in agriculture, she is a 2019 Global Youth Institute participant this year, a member of the Westman 4-H Poultry Club, and is employed by Agriculture and Agri-food Services Canada. In addition, she has played ringette for 10 years (softball and curling subsequently). Showing at science fairs for 10 years, this was her third year showing at CWSF. This year, Emily focused on creating a sustainable solution that could allow proper/effective food security. Continuing, she wishes to continue research for formulating a highly effective hydroponic fertilizer, allowing sustainability and combating food insecurity.