Science Buddies: "Ask an Expert"

Answer please. Also, what other things can speed up the process of degration organic substances?

How can I tell the amount of bacteria there is in, in any type of soil?

I reasearched somewhere that nitrogen plays an important role in the degradation speed of substances in the soil. How does it do it?

Can you shorten it and or change the words so that it is more scientific?

If I cut the substance, bury it approximately 2cm below the soil, and then water it, then this will critically speed up the degradation speed of that organic substance(s).

Hi Trexzert,
Welcome to the Ask an Expert forums. I gather you are doing a project related to soil microbiology? It sounds very interesting.

I merged all your questions into one topic. We ask that you keep a single topic for your project, and add questions to this thread. This will help the experts see the history of your project.

Adding nitrogen can speed up decomposition if the soil is "nitrogen limited" because it allows microbes to grow and reproduce faster.
There are many methods to analyze the microbial biomass in soil. Two common method are direct counts and plate counts. Those methods are described here:
http://www.tilthproducers.org/tpqpdfs/50.pdf
Yes, water does affect decomposition, because it is essential for the microbes that consume organic materials.
Your hypothesis sounds good. You could also say something like "smaller particle sizes and higher moisture contents of organic material will promote faster rates of degradation in soil".

Hopefully other experts will chime in with additional information.

I hope that helps,
Chris

I can take notes from the helpful links.

Still needing help on finding some helpful website that is not full of junk. The website is preferred to be related to my topic.

Hi Trexzert,

This is a great idea, and you can develop it into an excellent project. I recommend that you do as much background reading as possible and learn about soils. You will need to be an expert. Here is one website that has lots of information and lists other resources you can refer to:

http://www.isric.org/UK/About+ISRIC/Pro ... /GLADA.htm

For your project, you need a good way to measure the degradation of the biomass. Counting the bacteria using a plate count is one traditional way, but the problem is that you will have samples with between 1,000,000,000 and 10,000,000,000 organisms per gram of soil. In my experience, it’s really hard to tell if your results are significantly different using plate count techniques with this type of sample. But, this method is suitable for your project, and there is lots of information on this technique in the science buddies website. Be sure to read the safety precautions if you choose this method.

Another approach to measuring biomass is to either measure a microbial metabolite or a component of your sample. Here is an abstract of an article that measured a chemical found in fungi in soil:

http://cat.inist.fr/?aModele=afficheN&cpsidt=16198548

Here is another abstract that describes measuring the degradation of tar in soil by microorganisms by measuring carbon dioxide produced by the degradation using an instrument called GC/MS.

http://asae.frymulti.com/abstract.asp?aid=23021&t=2

The last two articles would not be practical unless you had access to an analytical laboratory with sophisticated equipment. I included these references to give you an idea about other scientists approach this type of problem. With additional investigation, it would probably be possible to identify something other than biomass that you could measure. One possibility would be to measure the carbon dioxide produced by the growing microbes using a homemade carbon dioxide monitor. If you are going to study the degradation of a unique substance, it would probably be possible to measure the disappearance of sample as it degrades. What type of sample are you going to be using?

Other factors that affect decomposition include temperature, the concentration of oxygen, the availability of nutrients other than nitrogen like phosphorous and carbon, the surface area of the biomass, as well as the presence of inhibitors such as heavy metal ions. Remember in your experiment, you will have one independent variable, and all other parameters (conditions of the experiment) will be controlled variables (identical), and you will have results that you can measure. And, hopefully, you will have time to repeat your experiment, and duplicate your results. Refer to the science buddies website for more information on designing your experiment.

One more comment about your hypothesis. When you have done more background reading, you will find that microbial growth depends on the presence of water. Without water, you will have no microbial growth. Since this is a well-established fact, perhaps you would want to change your hypothesis slightly to make your project more unique? Perhaps you could compare the results with different types of soil; with/without cow manure; with/without herbicide; on top of the soil/under the soil; or something else that you are personally interested in investigating. However, the water hypothesis is a very suitable topic also, but make sure that you have a way to measure the water so you can compare the amount of water to the quantity of biomass degradation.

I hope this helps you get started on your project. Please do write back if you need more information. Also, I don't know what science class you are taking, so let us know if you need more explanation of anything in this reply.

Donna Hardy

My teacher says my hypothesis is half-successful. Cutting the pieces and burying it in the soil has been explored already but he says I can do something with testing if moisture quality of organic substances affect the speed of organic degradation. Can someone show me one way that does not require sophisticated technology in order to figure it out?

Is there one good way to increase moisture in any organic substance?

Trexert-do you have any way to measure the moisture in your soil? At work I use a meter, but you may not have access to one. You can try and do a mass balance-weigh the amount of water you add to each soil sample, and then weigh again at the end (you will have some evaporation).
Is each soil sample closed-in other words, can water evaporate, or is it covered and sealed?

Hi Trexzert,

You can measure the moisture content by weighing your soil sample (in grams, since this is a science project); then spread the sample out in a thin layer on a flat heat-resistant surface like a baking sheet, and baking it overnight at 200 degrees Centigrade. You would weigh the dry sample as soon as it cooled, and then use the difference in weight to calculate the percent moisture in the sample. If you have family members that don’t like to have science fair projects in the kitchen, you could use an outdoor barbecue, or think of another way to dry the sample. Also, you would not want to add the dried soil sample back into the real sample because the microorganisms that are responsible for degrading the sample would be killed by the heat. So, plan to have enough soil so you can periodically remove samples for moisture testing.

You also need a way to measure your sample, but you haven’t told us what the sample is, so it’s difficult to suggest a suitable method for you. If you are planning to test a sample that contains sugar, for example an apple or other piece of fruit, you could measure the degradation by testing the pH of the sample over time. Sugars are converted to organic acids, so the pH would be expected to decrease over time. If you were testing the degradation of samples containing lots of protein, for example, cat food, then the pH would increase as amines are formed (this experiment would smell really bad; think of rotten fish). If you had a solid sample, for example pieces of wood, leaves, or peanuts, you could weigh the sample (dried in the oven) before and after degradation and calculate the loss of weight. You would need to put the sample in a porous bag with fine netting so it would come in contact with the soil, moisture, and microorganisms, but would stay together so you could recover it at the end of the experiment. So, what type of sample were you planning to use? We’ll try to think of something you can measure.

Donna Hardy

p.s. What are you going to use for a control sample?

Lets say I'm going to use banana peels.

Hi Trexzert,

Banana peels are composed of fiber along with some protein, fat, sugar, and minerals like calcium, potassium, phosphorous, and sodium. The mineral composition will not change during decomposition, but the fiber could be broken down to sugars, and then metabolized by microorganisms to organic acids, alcohols, and carbon dioxide. The protein will be broken down to amino acids, and then used by the microorganisms to make their own proteins. The banana peel will decrease in mass (weight) as it degrades, and the microorganisms in the soil will increase in mass and weight. If the samples are buried in the soil, the oxygen will be depleted and conditions will become anaerobic (without oxygen). If oxygen is available, the microorganisms that will grow will be molds. The temperature might increase as the microorganisms grow. So there are a number of possible measurements you could make:

1. Monitor pH, preferably with a pH monitor, but with pH paper if necessary.
2. Measure a sugar like glucose.
3. Measure the weight of the banana peel and/or the weight of the mold mass.
4. Measure the concentration of protein.
5. Measure concentration of oxygen and/or carbon dioxide.
6. Measure temperature in degrees Centigrade

I recommend that you investigate the possibility of doing multiple measurements. Please let me know if you have access to a pH meter, a spectrophotometer, a balance or scale, a glucose meter, or a thermometer. I can send more details of possible methods if you will let me know what resources you have available.

Donna Hardy

I'm thinking of getting two container and measuring the container in grams first. Then I'll put an amount of soil into the container from my backyard. After, I'll get another equal amount of soil from my backyard and put it in the oven to evaporate all the moisture. Then i'll measure and see how many grams of water the container weight well subtracting the weight of the container. I'll subtract the weight for the second container that has dry soil and compare the weight in grams between the one that contains moisture and the one that doesn't. Now, here is another question. The soil that contains no moisture because it has been heated in the oven, does it still contain bacteria and other micro-organisms or did they all perish from the heat? Can you tell the weight of bacteria in a, say 500ml container filled with soil?

Also, how does a pH meter help in this project?

Hi Trexzert,

Your plan to measure the moisture content of the soil at the beginning of the experiment is a good one. Weighing the soil before and after drying will give you the percent moisture in the soil. The microorganisms in the dried sample will be killed by the heating.

It is not possible to measure the weight of bacteria in soil. One type of microorganism that will grow on banana peel is mold or fungi. These microorganisms produce large colonies and the fungal mass they produce could possibly be separated from the rest of the sample and weighed. Bacteria are single-celled microorganisms about 1-3 microns in size and it is not possible to collect them to weigh them. You could "count" bacteria by diluting the soil sample and growing the organisms on nutrient agar. Did you read through the microbiology section of the science buddies website to learn more about techniques for growing microorganisms?

A pH meter could help this project because the banana peels contain molecules that microorganisms will convert from neutral molecules to organic acids, and this would cause the pH to decrease, or become more acidic. Banana peels contain some sugars which are easily converted to organic acids, and some fiber, which consists of long chains of sugar molecules. Fungi, in particular, have enzymes that can break down the fiber to the individual sugars, which can then be metabolized to organic acids. So using pH could be a way to measure the degradation of the banana peel. If you can't use pH, then you will need to keep looking for another method to measure the degradation (your dependent variable).

Here are some questions that should help you think about your project. You might have to do more research and background reading to answer all of these questions.

1. What is the difference between bacteria and fungi?
2. Are there any other types of microorganisms that might be present in soil?
3. What would happen to the banana peel if there were no microorganisms present?
4. What would happen to the banana peel if there is no water present?
5. What is the difference between a monosaccharide and a polysaccharide?
6. What is your hypothesis? (Write this statement as a question down first, as it will help you plan a better experiment).
7. How big is a micron?
8. What could you use for controls?
9. What is your independent variable?

Let me know if you need any help with any of these questions. You are on the right track to have a great project!

Donna Hardy

Hi Trexzert,

Here are a couple of specific suggestions for measuring the degradation of the banana peels.

1. Measuring glucose: here is a website that describes how to adapt a glucose meter, used to measure glucose in blood samples of diabetics, can be adapted to measure glucose in a different medium.

http://www.genengnews.com/articles/chti ... 624&chid=3

Glucose meters are designed to be used with blood samples, so they will not give accurate results with other types of samples such as soil. The authors in this study used a glucose meter that was calibrated with pure glucose in the culture medium they were using. If you had access to a glucose meter and some glucose test strips, you could calibrate the meter using glucose added to soil samples. Then you would periodically take samples periodically and measure the glucose in the samples. Glucose is used by many organisms, including humans, as an energy source. Banana peels contain sucrose and fiber, which are broken down to glucose and other monosaccharides (sugars), so this might be a good analyte to measure. Please let me know if this is an option for you, because you will need more information on the chemistry of how glucose meters work, and you will need to find pure glucose to use as a standard. It would be great if you could do this part of the project, but don't worry if you can't, because I have another idea below.

2. Measuring weight of banana peel. You could have a complete project that would satisfy all of the requirements of a science fair project just by measuring the weight of the banana peel as it degrades. To measure weight accurately, you would want to weigh each wet banana peel and then dry it as you are planning to do with the soil samples. This would give you the dry weight of the sample at the beginning of the experiment. Then you would bury the banana peels, and periodically dig one peel up, and measure the dry weight. If there is enough time for complete degradation, you would expect the banana peel to disappear as it is broken down to individual molecules. To do this experiment accurately, you would need to put each banana peel in a porous bag made with fine netting that would not degrade, but that would allow moisture and microorganisms to have access to the banana peels. A section of pantyhose works perfectly for this type of experiment and would be the least expensive option if these are available. There are other non-biodegradable options available for porous bags, but you would have to find it before you start your experiment. I recommend that you plan to have 4-6 bags of banana peels for each soil sample you are testing. You could tie a string that would be visible on the top of the soil, and once a week, gently pull up one bagged banana peel and measure the dry weight.

3. Temperature: Microorganisms can produce heat as they grow, and if you had a thermometer, you could measure the temperature of the sample as it degrades. And, this reminds me. What is the ambient temperature where you live? If it's not above 65 degrees F during the day (18 degrees Centigrade), then please ask your parents if you can do your project inside.

You should stop and think about your science fair board at this point. You will want to plot your results on a graph. What measurement will be on the x-axis? What about the y-axis?

3. Visual observation and photographs. With this experiment, you should plan to make written observations and do plan to take photographs of your samples as they degrade. Your written observations will make a very important addition to the results that you measure. On your main graph of results, you could include a drawing, description, or photograph of the banana peel. Do you have a lab notebook to record your experiment in?

I have noticed that your project is due on January 11. This means that you should try to set up your project within the next 7 days and get started. Degradation of banana peels will take time, so you want to allow at least 4 weeks to make measurements, and allow at least one week to do your final write up and prepare your board. If you set up your experiment next Saturday, December 6, take a sample to measure once a week, then you will have 5 data points for each soil sample to graph, and you would be finished with the experiment by January 3. That would be a perfect amount of data for a science fair project. So please start collecting all of the items you would need to start your experiment and do the measurements (make a list of items; you will include this list in the materials section of your science board).

You are going to need lots of bananas, so do encourage everyone you know to eat bananas and save the peels for you. I recommend that you have a banana split party and encourage your family and friends to help you with your project by eating bananas. You could store the banana peels in the refrigerator for a few days so they won't start degrading before you start your experiment.

Please go through my last two posts and try to answer all of my questions. Let me know if there's something you don't understand, and I will try to provide more information.

Donna Hardy

Heating the soil at 200C overnight will kill most the organisms present. There are some microorganisms that are tolerant to heat and will survive.

The weight of the bacteria and other microorganisms is not a factor to consider in this type of experiment.

pH is a measure of the hydrogen ion concentration and reflects whether the material is acidic (vinegar) or basic (sodium hydroxide, broccoli and green beans. Bacteria are inhibited by acid or low pH. If a soil or organic material is acidic bacteria will grow slowly or not at all. A pH meter or pH papers will allow you to determine if your organic material will support bacteral decomposition.

Matthew W. Mulanax

Wow, thanks to everyone that contributed so far, especailly Donna Hardy.

Now another question: Because Banana peels weight so less, can a scale or balance really identify it's weight. Would an electronic version of a scale of balance be better?

I just thought of something.

I can't really compare the soil that is moisture rich with the soil that is not because the soil that is not moisture rich has also few-to none bacteria/fungi in it.

I want to kick out the moisture but keep in the bacteria in the soil. Is there a way to do this that doesn't involve the death of micro-organisms?

You can air dry the soil without changing the native microbial population. Place butcher paper on a baking sheet and spread the soil out in a thin layer - 1 cm or so. It will take 2 weeks or so to dry the soil at room temperature. The microorganisms will remain alive until you begin the experiment.

Matthew W. Mulanax

Hi Trexzert,

If you are studying the effect of moisture on the degradation of banana peels, you will need to keep all other conditions exactly the same, except for the moisture content. You will need to use soil all from the same location and which has been exposed to the same drying conditions. You can't use soil from two different locations. If you did that experiment, you would need to make sure the moisture content of the samples was identical, and your independent variable would be type of soil, not moisture.

You can dry the soil samples in the oven if you want to, and then add microorganisms back in from a sample of cow manure, for example to repopulate the soil. The banana peel itself will also have normal flora on it that can start the degradation process. There will be a few spore-formers that will survive the drying process, but the primary groups of organisms that you want to have in your sample are fungi, as these will start the degradation process. Have you ever noticed what happens to a piece of fruit that has been damaged? It usually starts to grow mold first.

You do not have to dry the samples before you start the experiment. The sample that you dry for measuring moisture content can be a subsample that you remove from the main sample and use for testing purposes only, and then discard. You want to actually measure the percent water in your samples at the beginning of the experiment and at the end of your 4-week experiment. You can add more water to other samples of soil to prepare samples with a range of moisture content so you will have more data points on your graph of results. What range of moisture levels were you thinking about using?

What kind of scale do you have available to weigh samples? For single banana peels, it would be best to have a scale that will weigh to the nearest 0.1 gram. If you have a less sensitive balance, it will affect the accuracy and precision of your results, and you would need more banana peels per sample.

Please answer the questions from the previous posts and post the details of your experimental protocol. Writing down your experiment will help you think about the details of what you are planning to do.

Donna Hardy

Hi Trexzert,

Here is a website that describes the groups of microorganisms that are responsible for degradation or organic matter (banana peels) in composting.

http://www.css.cornell.edu/compost/microorg.html

This is essentially what you are doing in your project. You need to learn as much as possible about these organisms, so do look for other information that will help you understand how microorganisms grow. Do you think that the amount of moisture in a sample would affect the growth of these organisms?

Donna Hardy

I just had a crazy idea. If the moisture experiment works, then i'll try to double the moisture quantity in another banana peel experiment and see if that further increases the speed of degradation for banana peels.

Bacteria from cow manure may be different from the bacteria in the soil that contains moisture. So, here is what I'm going to do. I will use two plastic box (can hold 500g ea) that will fill 480g of soil and then dump all the soil in the oven. After heating the soil, I'll know none of them contains living organisms. Now, I'll put the banana peels in each box. Then, I'll take the soil and nearly fill up the two 500g box and add cow manure to each box to repopulate the soil with bacteria. I'll then pour in 20-50ml of water into one of the box. I have to measure both box weight in grams first before adding the water. Now I'll take data once a week. The genius part about this idea is I'll know the weight of the banana peel by just weighing the plastic boxes. Since I had a base weight in the beginning, when the banana degrades, so does it's weight. I can compare the box with water (moisture) against the box that doesn't. I can compare who lost the most weight in a given amount of time.

Here is my experiment.

Question: How to can I speed up the degradation process of organic substances in the soil?

Hypothesis: Higher moisture content in the soil will promote faster degradation rates.

Time: 4 Weeks

Materials:

-Soil of equal quality. Enough to fill 480g of your two plastic box.

- 2 Banana peels of similar quality.

- 2 Plastic box that should be able to carry 500g.

-Oven with baking sheet.

-Manure, (specifically cow manure).

-A scale

Procedure:

1. Go and fill the two plastic box with soil of same quality until it is slightly full. Now put all the soil into the oven and turn the heat on to 200 degrees. This will eliminate all the moisture and micro-organisms in the soil. Let the soil cool off overnight.

2. Get out a big bowl and put in the dried soil and cow manure. Mix it up so that the bacteria can repopulate the soil. You’ll know that the bacteria in both soil will be the same. The reason that I didn’t state how much manure to use is because it’s pretty hard to measure it without getting queasy. The amount of manure depends on you. I suggest it should not be of too little amount.
Set the bowl of mixed soil and manure so that bacteria can take time and live in the soil. Wait overnight.

3. Get out the two box and fill it partially. Then add the banana peel in each of the box and filled it up with the remaining soil completely. Measure both box and make sure they weight the same. Now, spray in 50ml of water into one box. This box will be the one that contains moisture. Now do not close the lids. Just put both box somewhere safe where it won’t fall. Do not put it outside as rain will ruin this experiment.

4. Every week, measure both box in grams and write down the data and any other interesting things you’ve noticed.

5. Now after week 4, compile your data and find a conclusion. Did the box with moisture lose more weight than the box that didn’t?

6. This is optional but highly recommended. REDO this experiment for greater accuracy. Also, see if this applies to other organic substances. For example, instead of using banana peels, use orange peels.

Hi Trexzert,

Thanks for taking the time to write down your materials and methods section. It shows you are really thinking about the details of your experiment. I do have some suggestions that I think will make your project more successful:

1. Your question is good. Your topic is really about finding the optimum moisture for composting banana peels. So you could substitute "banana peels" for "organic substances."

2. Your experiment is pretty good, but needs to be changed so you will get some results. Progress in science is made one small, controlled experiment at a time. Generally scientists rely on what others have discovered in the past, and the new experiments are based on previous results. So to design your experiment, you need to know what others have learned in the past. You are planning to put 50 ml of water in 500 grams of dry soil, which is 10% moisture. The microorganisms will not be able to grow with so little moisture, so your banana peel will not degrade. If you look at other references, you will find that degradation occurs between 40 and 80% moisture, and you need to know what optimum for banana peels is. You need to find these references and include them in your background information section and in your bibliography section. Since you are trying to find the optimum moisture for banana peel degradation, you need to set up at least 5 boxes of soil with moisture content of 40, 50, 60, 70 and 80% moisture. What about a control?

3. Drying sample in the oven at the beginning. Since you are designing the experiment, it is not necessary to include a step like adding cow manure that makes you queasy. Why don't you measure the moisture content of the soil you have available and add water to additional samples to make a range of moisture concentrations, and use the microorganisms naturally present in the soil for the degradation. If the starting soil has higher than 40% moisture, then you could air dry a sample under a fan overnight without heating to reduce the moisture content.

3. Quantity of soil. Is 500 grams of soil enough to cover a banana peel? What about 6 banana peels? I don't know. You will have to try this.

4. Measuring weight of banana peels: Weighing the whole box with soil plus banana peel will not measure the degradation of the banana peel. Algae in the sample, for example, will use carbon dioxide and moisture from the air to increase in the weight. Fungi can grow and increase the weight of the sample. Moisture from the soil might evaporate over the course of the experiment and cause a loss in weight. So, a change in weight won't be due to just loss of the banana peel mass. You will need to measure the dry weight of the banana peel over the course of the experiment, or use one of the other measurement ideas given earlier.

5. Number of banana peels. Unless you can measure pH, carbon dioxide release, or something else, you will need at least one banana peel per week from each soil sample to test for degradation by measuring the dry weight. So you will need 6 banana peels per box, and a way to measure the dry weight accurately. You could sample and dry the banana peels, and store them in a sealed plastic bag, and weigh them at school if there is a suitable balance for you to use there. Have you asked all of your friends to save banana peels for you?

6. It would be a great if you could actually measure the moisture content of the soil at the beginning and at the end of the experiment. You would need to have an extra 100 grams of soil from each box at the beginning of the experiment to do this. You want to demonstrate that if you start with soil that contains 40% moisture and add 100 ml of water per 500 grams of soil, that the final moisture content is 60%. You might be able to use a moisture meter, if one is available, rather than the oven drying/weighing technique.

7. Orange peels and other organic matter. If it best to do one carefully designed, well controlled, meticulously executed experiment, with quantitative results, than to do multiple experiments. You could improve your experiment by running each sample in duplicate and using more banana peels, but doing orange peels would not add the quality of this project, and the results might be confusing. Just focus and do a really good job with the banana peels.

Now, do you think you can write a revised experiment? What are you going to use as a control? Also, why don’t you plan your graph of results that will show your data? This will really help you see what you need to do. What will you plot on the x and y axis on your graph of results.

Does this help?

Donna Hardy

Hi Trexzert:

Heating the soil at 200C overnight will destroy most of the microorganisms in the soil. An alternative is to air dry the soil as follows –
Place butcher paper on a baking sheet, spread the soil out in a thin layer about 1 cm and leave at room temperature for 2 weeks.
There will be very little reduction in microbial numbers after air drying. After drying you can add water to bring the soil to the required moisture content for the experiment.

You can disregard the weight of microorganisms in the soil. Their contribution will not affect the experiment.

pH is a measure of the concentration of hydrogen ions in a solution. A low pH (1-5) indicates acidic conditions while a high pH (above indicates alkaline conditions. Bacteria are inhibited by acidic soil conditions. pH paper is readily available and will be adequate for your testing.

Matthew W. Mulanax

Hi Trexzert,

Here are two additional items that you need to consider in setting up your experiment.

1. Measurement by weight: You have not told me what kind of scale or balance you have available to weigh your samples. I had suggested trying to use a balance that will weigh to the closest 0.1 gram. However, if you don't have this type of balance available, you could probably also use a postage scale. Lots of people have postage scales, and these will weigh to the closest 0.1 ounce, or 2.8 grams. Hopefully you can find someone who will loan you a postage scale if you are still looking for this item. Using this scale would affect the accuracy of your results, and you would not be able to measure a difference in results if there is less than a 2.8 gram difference between the samples. Also, since this is a science project, you would need to convert ounces to grams; science fair results should always be done with metric measurements. Are you good at math?

Here is a website that gives more information about accuracy in scientific measurements.
http://fordhamprep.org/gcurran/sho/sho/ ... sson22.htm Also, read about precision, as this is a topic that applies to your project as well.

2. Controls: I have asked a couple of times about what kind of controls you are planning to use. Since you have not answered that question, and you did not include a control in the first experimental design, I think I need to give you more information on this topic. To make sure your results are valid and confirm that your future results are definitely the result of difference in moisture between your various samples, you need to analyze at least one and preferably two or more banana peels that are not exposed to soil or otherwise allowed to degrade. You should measure the dry weight of a fresh banana peel at the beginning of the experiment, but since you will have to dry this sample, it won’t be buried as a regular sample. In this experiment, this is your banana peel control. You would also need to measure the weight of each fresh banana peel that is to be buried in the various soil samples and label it so that you can compare the initial weight to the weight on the test date. The difference in the initial dry weight and the dry weight on the test date will reflect the weight of the banana peel that has been degraded by the microorganisms. Does this make sense to you? Let me know if you want me to do a theoretical example for you.

Why don't you read through all the previous posts on your project and make sure you have all of the information you need to start your experiment. I have asked lots of questions, so see if you can answer at least some of them. Let me know if you have any other questions.

Donna Hardy

For some unfortunate reasons, my home internet doesn't work and the telephone too. I've been trying to fix this problem. I won't be able to reply as quickly as possible. I'm at the school's computer right now.