What grows in the soil in a biosphere?

All things on our planet are linked by a giant recycling system called the biogeochemical cycle. I will demonstrate how our planet recycles and reuses everything we need to support life by making a small biosphere. I’ll also show how nutrients will be important for my biosphere’s life-support system?
Objective
In this project, I will make a mini biosphere to test the response of soil microorganisms to environmental changes in a closed system.
Introduction
Did you know that nature reuses and recycles? Most of the nutrients that are needed by the living part of the earth, or biosphere, are passed along by the biogeochemical cycle. Important for ecology and Earth science, a biogeochemical cycle is the pathway by which chemical elements and molecules move through both the living ("bio-"tic) and nonliving ("geo-" or abiotic) parts of an ecosystem (Wikipedia, 2007).
Chemical elements move through the biotic parts of an ecosystem by being part of organisms. Chemical elements also move through abiotic parts of ecosystems, like water, land, and the air. Some important chemicals, nutrients, and elements that are recycled through an ecosystem are carbon, nitrogen, oxygen, phosphorus, and sulfur. The biogeochemical cycle is called a closed system, because these elements are not lost or created (law of conservation of matter), but is constantly being re-used and recycled. Some examples of biogeochemical cycles are the water cycle, the carbon cycle, and the nitrogen cycle.
Terms
Biosphere
Biogeochemical cycle
Closed system
Nitrogen
Sulphur
Phosphorous
Carbon
Questions
What microbes will you find in the mud?
Why do the microbes layer in different patterns?
Materials and Equipment
Containers for collecting the mud and water samples (2)
Recycled, clean 0.5-liter water or soda bottles (4+)
Scissors
Small scoop or shovel
Plastic wrap
Rubber bands
Masking tape
Permanent marker for labeling
Some additives to test:
Shredded paper (carbon)
Powdered chalk (calcium sulfate)
Blood meal - an organic nitrogen fertilizer available at a nursery or garden center (nitrogen)
Hard-boiled egg yolk (sulphur)
Experimental Procedure
Go out and collect some mud from a muddy location. A good place would be near a stream, pond, or marsh. Scoop the sample into a container. Then collect some water, from the same location, in another container so you can keep your mud the consistency of a milkshake after you've brought it home. Bring your containers home and go wash your hands! If you have a cut or wound, you should wear latex or rubber gloves when collecting and working with the soil.
Prepare your bottles by removing the labels and cutting off the top spouts. You will later use one of the spouts as a funnel, so don't throw it away!
Prepare your additives:
Cut a sheet of used paper or newspaper into thin strips. This will be a source of carbon.
Mash the yolks of three hard-boiled eggs into a dry powder. This will be a source of sulphur.
Crush a few sticks of white chalk into a fine powder. This will be a source of calcium sulfate.
Purchase some powdered blood meal, an organic nitrogen fertilizer at a nursery or garden center.
Prepare your Winogradsky Columns:
Get your container with your soil sample and pick out all the sticks, leaves, and pebbles.
While stirring, slowly add the water (collected from the same source) to the soil until your mixture becomes like a milkshake. The amount of water you need to add will depend on how wet your soil is at the start. Be sure the mud is