Lab 5: Soil and The Carbon Cycle

Introduction

Do you ever think much about the soil under your feet when you walk to school? What is soil made of? How does soil behave under different weather and climate conditions? What lives in soil? Perhaps your family has a compost and you already know the importance of soil organisms in creating rich, dark soil. Farmers certainly know the importance of good, rich soil in growing healthy, robust crops. Understanding soil is also important to people who study the carbon cycle and climate change. This is because soils store a lot of carbon! As a matter of fact, more carbon is stored in the world's soils than is currently present in the atmosphere.

When we look at the soil beneath our feet, soil seems fairly simple to understand. Actually, soil is one of the most complicated reservoirs of the carbon cycle. Scientists agree that there are many unknowns about how soil might respond to climate change and that the following essential question needs additional research.

• What will happen to the vast amount of carbon stored in soils if the climate continues to warm?

In Part A, you will learn about soil composition, decomposition and soil respiration. You will design and carry out a laboratory experiment on how soil respiration rates might be influenced by one of the following climate-related variables - temperature, soil moisture, soil nutrients, soil fertility, and soil type.

In Part B, you will use videos and readings to explore a very special soil with an interesting past and an uncertain future—the permafrost.

By the end of this investigation, you will be able to:

• Describe the role of soil respiration in transferring carbon from the soil to the atmosphere
• Describe the possible impact of a warming climate on permafrost
• Use systems thinking strategies to identify any feedbacks between a thawing permafrost and the carbon cycle.

Keeping Track of What You Learn

Throughout these labs, you will find two kinds of questions.

• Checking In questions are intended to keep you engaged and focused on key concepts and to allow you to periodically check if the material is making sense. These questions are often accompanied by hints or answers to let you know if you are on the right track.
• Stop and Think questions are intended to help your teacher assess your understanding of the key concepts and skills you should be learning from the lab activities and readings.

Your teacher will let you know which answers you should record and turn in.