Soil Moisture
Recommended for grades 9–12.
Introduction
Soil moisture is water that is held in the spaces between soil particles. Dry soil is made up of minerals and air pockets, called pore spaces. A typical volumetric ratio would be 55% minerals and 45% pore space. As water is added to the soil, the pore spaces begin to fill with water. Soil that seems damp to the touch might now have 55% minerals, 35% pore space and 10% water. This would be an example of 10% volumetric water content. The maximum water content in this scenario is 45% because at that value, all the available pore space has been filled with water. This soil is referred to as being saturated, because at 45% volumetric water content, the soil can hold no more water.
Soils collect, store, and release water. Collection occurs as water enters the soil through surface pores in a process called infiltration.When forces of retention within soil are greater than removal forces water storage is possible. Water release takes place when plant uptake, drying, or gravitational forces overcome retention.
Objectives
In the Preliminary Activity, you will gain experience using a Soil Moisture Sensor and learn soil moisture measuring technique as you determine the volumetric soil water content of a soil sample.
After completing the Preliminary Activity, you will first use reference sources to find out more about soil moisture and factors that affect it before you choose and investigate a researchable question dealing with soil moisture.
Sensors and Equipment
This investigation requires each of the following Vernier sensors and equipment (unless otherwise noted):
Additional Requirements
You may also need an interface and software for data collection. What do I need for data collection?
Download Experiment Preview
The student-version preview includes:
- Step-by-step instructions for the Preliminary Activity
- List of materials and equipment
Note: The experiment preview of the Preliminary Activity does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.
Standards Correlations
See all standards correlations for Investigating Environmental Science through Inquiry »
Experiment 11 from Investigating Environmental Science through Inquiry Lab Book
Included in the Lab Book
Vernier lab books include a CD with word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.