Contact Info

Tyson Ochsner

Professor

Plant and Soil Sciences

Oklahoma State University

371 Ag Hall

Stillwater, OK 74078

Phone: (405)-744-3627

tyson.ochsner@okstate.edu

Temperature Exercises, D.L. Nofziger

Soil Temperature Exercises

1. Consider the temperature vs time graph. Note that the minimum temperature is zero and the maximum is 30 °C as specified in the text windows above the graph. The minimum temperature occurs at 10 days after the beginning of the year (January 10). This is specified as the Time lag in the text box above. The maximum temperature occurs near day 190. Complete the following table.

 Depth (m) Maximum Temperature(°C) Day of Maximum Minimum Temperature(°C) Day of Minimum 0 30 190 0 10 1 2 3 4 5 10

1. What is the thermal diffusivity of a soil? What soil properties influence the thermal diffusivity of a soil? How does its value affect the shape and amplitude of the temperature vs time curves?

1.  Consider the temperature versus depth graph.
1. On January 1, what is the maximum temperature in the profile? At what depth does it occur? What is the minimum temperature in the profile? At what depth does it occur?
2. Describe the temperature vs depth curves for the first day of each month of the year.
3. How do the temperature vs depth curves change when the diffusivity changes?

1. The water content of a soil can change the thermal diffusivity from approximately 0.05 to 0.08 m2 day-1. Does a difference of this magnitude have a major impact upon the temperature vs time or temperature vs depth curves?