Rot

Experiment Title:

Rocking with Rot

Objective:

Learn about how important rot is on our planet and what things rot well verses what things do not.

Background on Rot:

What is that stink? That putrid smell, that makes us queasy and want to walk away from the area we just entered, could very well be rot! Rot is a natural process of decay created by the breakdown of organic materials by microbes, fungus, and various insects. 

Let’s think about a very simple scenario the life cycle of a tree. A Tree (in this case) grows from a seed. As that seed grows it extends roots into the ground and develops a trunk (the tall main support of the tree). Whether this tree is deciduous (loses their leaves in the fall and regrows them in the spring) or evergreen (has needle like leaves that are replaced every few years but the tree never fully loses its leaves throughout the year) does not matter but for what we are talking about let’s say it is a deciduous tree. As this tree develops it will be likely to flower and fruit, this may mean the tree has lots of beautiful flowers all over it or more likely has green flower buds all over that may turn into seeds, fruit or nuts. Each year or every other year (biannual trees such as fruit trees produce fruits in abundance every other year) they will produce a lot of flower and seed or fruit waste each year. As the tree continues to grow its roots need to strengthen to support the ever growing tree, thus woody larger roots develop. This continues year after year until the tree reaches the end of its life. Without rot the fruit/seed/leaf waste would build up on the ground. This waste would build up every year a bit more, blocking water from getting to or being released from the soil. It would also prevent seeds from settling in to soil and creating new trees. When the tree dies the roots, leaf/fruit/seed waste and the trunk and branches of the tree would be left behind blocking new plants from growing and trapping nutrients for other plants or creatures to use. This would lead to life slowing dying out in that area, but luckily we have rot!

Rot is the natural breakdown of waste materials from a plant, animal or living organism. For many of us rot appears to be a disgusting process, but is no different than the digestion that takes place in our internal organs (stomach, small intestine and large intestine). These materials are broken down by insects, fungus and bacteria in order to release nutrients trapped in the waste materials and use it for that organism’s life and reproduction as well as returning those nutrients to the soil that the waste materials are left upon. Let’s look at how these different organisms work to break down waste materials and keep the cycle of life flowing throughout our planet.

There are four main organism types we are going to look at when talking about rot: bacteria, insects, fungus and animals. Animals are a great organism type to start with. Animals are the biggest of the organisms that we will discuss. Due to their size animals can help bacteria, insects and fungus in their breakdown of materials. Animals when walking through an area can break, damaged or smash plant materials such as fruit, leaves and stems. When those things are damaged by animals moving through the area it opens up their structures to fungus and bacteria and insects, structures that most of the time would take months, possibly years for bacteria or fungus to get into. The easier it is for the bacteria or fungus to get into organic matter the sooner that those organisms can begin to break down the waste materials. Besides animals damaging waste materials for easier access for fungus and bacteria, animals digest waste products as well. Think of a salad, the salad is made up of leaves (the lettuce), fruit (cucumbers), seeds (sunflower seeds) and stems (celery stalks). Each of these materials represent a waste product from a plant. When animals eat and digest these materials they break down the materials, keeping nutrients and minerals that they need to survive and thrive. Any materials that are in excess of what they need or are not needed by that organism are removed from the animal as waste. This waste can then easily be broken down by bacteria, fungus and insects.

Now let’s look at insects. Many insects will burrow into plants or waste materials from other living organisms to lay their eggs. These eggs will develop into larvae. The larvae will eat the waste materials as they develop, eating more and more the larger that the larvae get. When the larvae develop into adult insects they can lay new eggs in the remaining waste and can begin the cycle again.

Bacteria is one of the most versatile sets of organisms on the planet. Bacteria covers all living organisms and is essential for the breakdown of many materials. Think about our digestive system. The only reason we are as capable of digesting materials as we are is because our bodies work with bacteria in our intestines in order to have the bacteria break down the materials we eat to various extents. When we have a good balance of gut bacteria we are healthy and able to get all the nutrients we need from the food we eat. Bacteria can also be used to help us produce foods we like to eat. Think of cheese, cheese is created from bacteria breaking down milk. Yogurt is another example of this type of breakdown but requires a different type of bacteria.

The last organism type we will discuss is fungus. Fungus is a special type of organism. Without fungus most plants would not have strong enough root systems to survive and thrive, but along with that fungus is needed to break down very tough materials such as wood. The cellulose in many hard plants is very difficult to break down, but certain fungi have become specialists in this field and break down wood over time helping to replenish forests with nutrients required for new plants to grow and providing edible materials for other organisms through the production of certain mushrooms. Mushrooms are the fungi’s way of reproduction and can vary from being harmless to highly toxic.

There are many different organisms that work together to break down waste materials in order to replenish nutrients and minerals to soil and make it possible for new plants, insects, animals, bacteria and fungus to thrive. All of these organisms are vital in one way or another in order to assure that materials are broken down as fully as possible. Now that we know a bit more about the different organisms involved let’s look at their similarities and differences. As well we should look at how the breakdown of materials will help or hinder plants or other organisms from thriving.

Materials

• Station One

o   Microscopes

o   Prepared Slides

• Station two

o   Wooden Board

o   Two strings

• Station three

o   Mushrooms

o   Lab Mats

o   Plastic Knives

• Station Four

o   Plastic Containers

o   Bananas (prepare one banana a week ahead of time)

o   Compost

o   Dirt

o   Clay

Method

This lab will be a multi-station lab that allows the students to look at different aspects of rot and how each part is important to life on our planet.

Prepare Experiment

1.      Station One: The small side

a.      Setup two to three microscopes on the bench making sure the kids have enough room to work around each other

b.      For each microscope setup one to two slides that show things that cause or need to rot

c.      Have prepared notecards about why each slide (i.e. thing on the slide) is a necessary component of the cycle of rot

2.      Station Two: Small and Mighty

a.      Using the prepared board have the kids try to get their string to all of the nutrients, minerals, and water that a plant needs to thrive.

                                                    i.     Note: the string you use for this should not be long enough to reach all of the materials and should be mounted on the trunk side

b.      Now have the kids use the other string on its own to try to get to all of the nutrients and minerals it needs to survive

                                                    i.     Note: the string you use for this should not be long enough to reach all of the materials and should be mounted on the fungus side

c.      Now have the kids use both strings and see how symbiosis helps the plant and fungus to both grow successfully

3.      Station Three: Fungal Reproduction

a.      Setup the lab table with lab mats, mushrooms, and knives

b.      Using notecards show the kids the steps in the dissection process

c.      Have them identify the main parts of a mushroom

d.      Show them that the mushroom is the last stage in growth of a fungus and the mushroom produces spores that generate new fungus

4.      Station Four: Put it all together

a.      Banana preparation

                                                    i.     Take the banana, peel and all and smash it together, add a little water and place in an airtight container to rot for a week

                                                   ii.     On the day of the lab take a fresh banana, peel and all, and cut it into a few pieces and place into an airtight container

b.      Compost preparation

                                                    i.     Using a compost from the store (will be very broken down and will be much safer for the kids to look at in a sealed container than fresh compost) place compost in the bottom of the container and squish it together

c.      Dirt preparation

                                                    i.     Using dirt from the store or your yard place dirt in the container, leave it loose as it is meant to demonstrate the ease of movement in dirt

d.      Place all of the containers on the table, do not label any of them

e.      Have the kids examine each container and write observations about each one

f.       Have the kids determine the order of rot that the containers are and explain why they think the containers would be in that order

5.      Station Five: Best soil

a.      Provide samples of clay, sand, dirt, rock (solid and pumice)

b.      Have the kids use small samples of each

c.      Have the students test:

                                                    i.     How well the samples stick together

                                                   ii.     How well things push through the material

                                                  iii.     How well the material absorbs or drains water

d.      From the results of their testing have the students make a small amount of a mixture of the different materials to make a soil they think will provide plants the best chance of thriving

Run Experiment

1.      Break the kids up into 5 groups and send one group to each station 
2.      For each station the kids will have 5-10 minutes to work on their lab
3.      Have the kids work through each station
4.     After the kids have worked through each station discuss what they should have learned from each one

Analyze Data

     1.      Station One: Discuss how each living organism is made up of cells that contain vitamins and nutrients. Have the kids talk about what they were able to see with each of the samples and the similarities that they could find between the plants, insects and animals. 

      2.      Station Two: Discuss how things that we assume are bad for plants such as fungus actually create beneficial relationships between the fungus and plant in order to make sure both organisms can survive and prosper. By working together, the plant can use the machinery from the fungus to get nutrients and minerals from the soil that the plant may have trouble extracting from the soil on its own. The fungus gets water from the plant that it would have trouble extracting from the soil on its own. Plants that grow with this symbiotic relationship tend to grow bigger and stronger with longer lives than plants that do not have this relationship. When the plant dies other fungus will take over and break down the plant into its base nutrients and make those nutrients available for new plants. 

     3.      Station Three: Discuss how the mushroom is the last stage in the fungus’ life cycle and how by cutting the fungus into a simple cross section you can see how the fungal roots grow into the mushroom, creating a trunk, a cap and gills. The gills of the fungus release spores from the fungus. In order to release the spores, the fungal roots send water up through the trunk into the cap and to the gills. The gills secrete (release) drops of water into each spore pod, when the water droplet is large enough it causes the spore to be released. The water droplet is small enough that it evaporates almost immediately when the spore is released allowing the spore to be carried through the air to a new location and restart the fungal life cycle.

      4.      Station Four: The students should see that the order of the containers should make a circle. The bananas are the reproduction mechanism of the banana plant. The fresh banana falls to the ground containing the seeds of the plant, this is then broken down by bacteria and fungus (the mushy banana) however some of the seeds stay intact during this process, once the main banana is broken down you are left with the composted remains with a seed or more left, the composted remains are compacted a bit and with some luck some seeds have survived that can germinate in the remaining soil containing the broken down nutrients from the original plant. These seeds can grow into a new plant and eventually produce new bananas.

      5.      Station Five: The students should see that each material has its own merits and that a mixture of different materials can provide a very good soil for many different types of plants to grow. One thing they may realize is that certain plants are specialists and develop specifically to survive in specialized soils.

Conclusions

Rot is thought of in many instances as something that is gross, however we know it is a natural process just like eating and digestion is a natural process for us. By understanding rot and how it is beneficial for plants and animals we can better understand how our entire planet works. We can understand how bacteria, fungus, plants, insects and animals all work together to keep the cycle of life moving along and functioning.

Make It Your Own

Now that we understand the interconnection between different living organisms on the planet, think about man made materials and how they might change, help or hinder the cycle of life that has developed on our planet.

Extension Activities to do at home

Some of our favorite foods are made from rot. Think about cheese, cheese comes from the breakdown of milk by bacteria. The longer the milk has been breaking down the harder the cheese. In your fridge look at the different types. Most cheeses will say how long they have been aged. Feel each cheese and see how hard each one feels, do not forget to look at cheeses like cottage cheese (this cheese will have been broken down by bacteria for only a few weeks in many instances).