If pH levels in consecutive amounts of compost concentration are compared, then mesocosms with higher concentration will have less sustainability shown through pH because higher concentrations of compost could potentially lead to imbalances in soil pH, nutrient levels, and leaching in a larger outlook.

A mesocosm is an experimental system used in ecological or environmental research to simulate natural ecosystems on a smaller scale. Mesocosms are designed to mimic certain aspects of natural environments while allowing researchers to control and manipulate various factors for experimental purposes. Mesocosms with resources aim to create realistic and functional ecosystems that enable researchers to investigate ecological processes, species interactions, ecosystem dynamics, and responses to environmental changes under controlled conditions. They serve as valuable tools for studying complex ecological phenomena and testing hypotheses in a controlled experimental setting. A variety of observations were made on the mesocosms, both before and after the sealed growth period. 

Compost is a nutrient-rich organic material that is created through the decomposition of organic matter such as food scraps, yard waste, leaves, grass clippings, and other biodegradable materials. It is often referred to as "black gold" due to its valuable properties for soil health and plant growth. Composting is also a natural process that occurs when microorganisms such as bacteria, fungi, and other decomposers break down organic matter into simpler substances. These microorganisms thrive in aerobic (oxygen-rich) environments, where they consume organic materials and convert them into compost. Compost specifically  from the city of Calgary used in this experiment is “100% natural and made up of the food scraps, leaves, branches, and yard waste Calgarians have been putting in the Green Cart composting program.

pH stands for "potential of hydrogen"Panamaand is a measure of the acidity or alkalinity of a solution. It quantifies the concentration of hydrogen ions (H⁺) in a solution. The pH scale ranges from 0 to 14, with 7 considered neutral. Values below 7 indicate acidity, with lower numbers indicating stronger acidity, and values above 7 indicate alkalinity, with higher numbers indicating stronger alkalinity. pH 0 to 6.9: Acidic, pH 7: Neutral, pH 7.1 to 14: Alkaline (or basic). pH plays a crucial role in various biological, chemical, and environmental processes. In biology, for instance, pH levels are critical for maintaining the proper functioning of enzymes and metabolic pathways within living organisms. In chemistry, pH affects the solubility and reactivity of substances. In environmental science, pH influences the health of aquatic ecosystems and the availability of nutrients to plants. Monitoring and controlling pH levels is important in many industries, including agriculture, water treatment, food production, and manufacturing, to ensure optimal conditions for processes and products. 

Sustainability within a mesocosm can indeed be assessed by considering various factors such as waste accumulation, nutrient levels, and pH, among others. Monitoring soil pH within the mesocosm can provide valuable information about its suitability for plant growth and microbial activity. An optimal pH range is necessary to facilitate nutrient uptake by plants and maintain microbial diversity and activity. Deviations from the ideal pH range can affect nutrient solubility, soil structure, and overall ecosystem health within the mesocosm.

Hydrogen peroxide solution can play a valuable role in mesocosm research by serving as a versatile tool for sterilization, oxygenation, oxidation, experimentation, and hygiene maintenance. However, it's important to use hydrogen peroxide with caution and in accordance with appropriate safety protocols, as it can be corrosive and harmful to human health and the environment at high concentrations.  It is also proven in managing microbial pests plants growing indoors and outdoors, This active ingredient prevents and administers bacteria and fungi that cause serious plant diseases. 

 

 

Variables 

Manipulated 

The main independent variable is the percentage in concentrated compost in each mesocosm, varying 0% to 40% creating a possible change in data while comparing. 

Responding 

Level of pH measured and analyzed results, as well as lower or more sustainability in the mesocosms depending on concentration of compost. 

Controlled 

Controlled components of the experiment include specific and exact methods of preparation for all samples/mesocosms, for example using the same tools and technique to gather or collect materials or data to ensure accurate results for all samples. This includes, but is not limited to the same amount of water treated with, and solid preparation and amounts for solid in critical in a test of sustainability in the case of the growth of a plant. It is also important to ensure that the species of plant used in the experiment are all the same, for different species and types of plants react differently depending on circumstances. Environment is also very important to regulate, making sure all mesocosms are exposed to the same and right amount of required sunlight in order to provide accurate results.

 

Materials 

• 100 ml of 3% hydrogen peroxide solution
• 500 ml of Tap Water
• 150 ml of Distilled Water 
• Large, 2L+ Container
• Stir Sticks
• ~ 200g of Organic Compost
• Fine Mesh
• 15 Pisum sativum (Maestro pea) seeds
• Electronic scale
• 6 Containers, at least 275 ml in volume
• Scoopula
• 2 ml Pipette
• 3 Spot Plates
• 50 ~3cm long pHydrion INSTA-CHECK pH indicator strips

 

Procedure 

Preparation (to be done 1-2 days in advance):

1. Prepare 15 pea seeds by germination. Place pea seeds in a shallow container, and add enough water to fully cover the seeds.
2. After 24 hours, place the seeds in a wet paper towel, and wait approximately 24-36 hours for pea seeds to germinate.

Mesocosm set up:

3. Set aside five 1L mason jars.
4. Label each mason jar with different compost percent composition of soil 0%, 10%, 20%, 30%, and 40%.
5. In a separate container, use a scale to measure 200g of small pebbles and rocks.
6. Repeat five times for each mesocosm; then place pebbles as the base layer inside each mason jar.
7. From a fine mesh, cut out 10 pieces of mesh similar to the shape of mason jars. Place 2 mesh layers in the base of each mason jar, covering the whole pebble layer.
8. In a separate, large container, mix 1.25L of soil and 100 ml of 3% hydrogen peroxide solution. Stir this mixture for 5 minutes, or until hydrogen peroxide is fully absorbed into the soil.
9. Let the soil dry for 30 minutes - 1 hour.
10. On an electronic scale, measure out 25g, 50g, 75g, and 100g (corresponding with 10%, 20%, 30% and 40%) of compost for each of the five mason jars.
11. Then, measure out 250g, 225g, 200g, 175g, and 150g (corresponding with 0%, 10%, 20%, 30% and 40%) of sterilized soil.
12. Mix together the measured soil values with their corresponding values to create soil mixtures containing 0%, 10%, 20%, 30% and 40% composition of compost.
13. Carefully pour soil mixtures into their corresponding jars; ensure that the pebble and mesh layer does not move around during the pouring of soil.

Measuring pH:

14. Using a scoopula, take out five soil samples from different places in a mesocosm, roughly estimating 2g. Then, using an electronic scale, measure out 2g of soil from each sample. If there is more soil needed, take samples from the same place. If there is excess, place any extra soil back into the mesocosm.
15. Repeat step 14 for every mesocosm.
16. Place each 2g soil sample into a spot plate depression. Ensure that you label or place the soil samples in a way that you will remember which samples came from which mesocosm.
17. Using a 2 ml pipette, add 2 ml of distilled water to each sample of soil.
18. Thoroughly stir each distilled water-soil mixture with a stir stick for 20 seconds, until the soil appears fully combined with distilled water.
19. Cut 25 3 cm strips of pH indicator paper. Place one strip of pH paper into each spot plate divet containing distilled water and soil mixture. Ensure pH strips are fully submerged into mixtures before taking them out and recording pH.

Completing Mesocosms:

20. Using a flat tool, lightly compress the soil.
21. Using a long, round tool approximately 1-2 cm in diameter, create three holes in the soil 2-3 cm in depth. 
22. Carefully place one pea seed into each hole, then use the surrounding soil to cover up the seeds. If seeds have already begun to sprout, place the seed so sprouts face down in the mesocosm.
23. Repeat steps 14-16 for each mesocosm.
24. In a clean measuring cup, measure out 100 ml of tap water. Carefully pour water into mesocosms, ensuring not to surface the planted seeds.
25. Tightly seal mason jars.
26. Place finished mesocosms in an area exposed to lots of sunlight, such as a windowsill.

After the one month waiting period:

27. Unseal the mesocosms.
28. Repeat steps 14-19, now that the mesocosms have had time to develop.
29. Once finished, safely dispose of the mesocosms, secluded from the environment.

Observations 

In order to provide results from measuring pH, observations of before and after were accounted for.

Before sealing mesocosm samples (36 days before analyzing and opening): 

No visible signs of contamination or plant growth were observed, soil was in good condition; moist. No noticeable unusual smell, in a stable state. 

After sealed period of the mesocosms (36 days after sealing of mesocosms): 

Distinguishable plant growth in all mesocosms but some seeds were not successful in sprouting, soil was not bare dry, there was visible water condensation and moist soil. Clear root growth can be observed from the side of glass jars. Strong stink smell, possibly from release of methane gas or chemicals, upon opening there was a hissing noise proving the mesocosms were sealed tightly and no outside air contamination. 

 

 

Analysis 

From observing the chart, we can conclude that comparing each sample in rows they don't have much significant difference, but by comparing the samples in columns, we can some larger difference, but accounting for any limitations and possible errors, concentration in compost has somewhat impact on pH, this is because or organic acids which appear in compost. But by just observing the graph and chart we can see that the average pH level rises depending on compost concentration, many of the average pH levels are outside the desired sustainability level.

Comparing the prior sealing chart and graph and after sealing collected data, we can analyze a large difference between pH levels in samples, but as well as average levels, considering any possible errors, pH levels remain higher than before and increase based on compost concentrations. Prior to sealing, many pH levels were already higher than desired pH levels for soil, but from data collected after sealing we can observe much larger levels of pH not just average but individual data points.

    

 

From a chart made from pH level differences before and after, we can observe there were some minor increases in pH, but also decreases based on the samples collected, but also consider any limitations that could have caused this.

 

 

Standard deviation 

 

 

Sample calculation for mean pH  - 0% compost, prior to sealed period

x̅ = xn

x = 6.3 ± 0.1, 6.8 ± 0.1, 6.7 ± 0.1, 6.9 ± 0.1, 6.5 ± 0.1

n = 5

x̅ = 6.3 ± 0.1 +  6.8 ± 0.1 + 6.7 ± 0.1 + 6.9 ± 0.1 + 6.5 ± 0.15

x̅ = 6.64 pH

Sample calculation for standard deviation - 0% compost, prior to sealed period

S (Standard Deviation) = (x-x)2n-1

S = (6.3-6.64)2+(6.8-6.64)2+(6.7-6.64)2+(6.9-6.64)2+(6.5-6.64)25-1

S =  0.240831… pH

Standard Deviation = 6.64 ±  0.24 pH

 

Since standard deviation is close to zero means individual data points are very close to the mean.

 

The purpose of this experiment was to understand the relationship between compost concentration and sustainability. In summary, based on the results from own collected data, and background research, this supports the hypothesis by showing the concentration of compost at different levels have minor impacts on sustainability in environments, this was shown through the variety of pH digits from differing mesocosms, but do consider the limitations and possible errors produced that could have impacted the results.

 

In urban environments, compost is often used for greening projects, such as parks, gardens, and green roofs. These green spaces contribute to urban sustainability by improving air quality, reducing urban heat island effects, and providing habitat for wildlife. Proper management of compost concentration and pH levels is essential to ensure the success of these projects. By monitoring soil pH and adjusting compost application rates as needed, urban planners and landscapers can create thriving green spaces that support biodiversity, enhance urban resilience, and contribute to the overall well-being of urban residents. 

Similarly In organic farming systems, synthetic fertilizers and chemical amendments are avoided in favor of natural inputs like compost. Compost serves as a valuable source of nutrients and organic matter. By carefully managing compost concentration and pH levels, organic farmers can ensure optimal soil conditions for plant growth while adhering to sustainable principles. They may conduct soil tests to assess pH levels and adjust compost application rates accordingly to maintain a balanced pH. This approach helps sustain soil fertility, reduces reliance on external inputs, and promotes environmentally friendly agricultural practices.

The relationship between compost concentration and sustainability is closely intertwined, as composting offers numerous environmental, economic, and social benefits. By concentrating efforts on composting organic materials and utilizing compost effectively, individuals, communities, and industries can contribute to a more sustainable and resilient future.

 

Some possible improvements next time would include using a more reliable source of measuring pH, for in this instance the level of pH was used through human judgment on what the pH strip displayed, this could have caused errors in human judgment, and an electronic pH meter would provide more accurate outcomes.

The relationship between compost and sustainability does not always mean plant growth associated with seedlings, for they have different reactions compared to pre developed plants, or other types of growth for example bulbs. Further experiments related to mesocosms should include developed rooted plants to allow a broader niche of results and data.

Another possible error that could have occurred or impacted the outcome was the unknowing of whether the hydrogen peroxide solution used to sterilize the soil was able to fully evaporate from the soil prior to sealing the mesocosms. This could have impacted the results for hydrogen peroxide is highly acidic and if present in the soil could have affected the final verdict. Instead next time allowing more time for the solution to evaporate or use alternate methods of sterilization like heat treatments. 

The mesocosms were meant to reach equilibrium before measuring pH values, another possible way that may have affected the reliability of the results, the results may not primely represent sustainability, as the seed may have not have had enough time to fully develop, and longer experimentation period or development period would be adequate to reach equilibrium.

 

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I truly would like to thank my mother, from helping me with the design of my trifold, and my brother for helping me with the experiment and topic components in general.