Why do we study soil temperature?

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Why do we study soil temperature?
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Where do we study soil temperature?
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Soil Thermometer

• Used to take temperatures at 5 and 10 cm depths

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Calibrating the Soil Thermometer

• Basically, we compare the soil thermometer to a
  calibration thermometer, and adjust the soil
  thermometer.

First, we need to check the calibration
thermometer!!
by dipping it in an ice bath.
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Checking Calibration Thermometer

• Submerge thermometer in ice-water bath
• Let sit for 10-15 minutes, stirring thermometer
  occasionally
• Read the thermometer. If it reads between -0.5
  C and 0.5 C, the thermometer is fine.
• If the thermometer reads greater than 0.5 C,
  check to make sure that there is more ice than
  water in your ice-water bath.
• If the thermometer reads less than -0.5 C, check
  to make sure that there is no salt in your
  ice-water bath.

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Soil Thermometer Calibration

• Add the soil thermometer to the ice bath
• Wait 2 minutes
• Read both Soil Thermometer and calibration
  thermometer.
• If they agree to within 2 C, the soil
  thermometer is ready to use.
• If not adjust the soil thermometer, using a
  wrench, until it reads with 2 C of the
  calibration thermometer

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When to Do the Soil Temperature Measurements

• Soil temperature is a weekly measurement, but you
  can do it daily.
• Try to do the measurement at about the same time
  of day
• Take data near the atmosphere station or near the
  soil moisture site
• Also measure soil temperature measurement
  whenever a soil moisture data are taken
• Seasonally (4 times a year), measure soil
  temperature every few hours during the day for 2
  consecutive days
• provides a diurnal reading of soil temperature
  change
• diurnal sampling in March, June, Sept. and Dec.
  are preferred

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Soil Moisture
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Soil Moisture

• Why is it important to take soil moisture
  measurements?

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Why Soil Moisture Is Important
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Scientists want data for

•   Help track the water cycle in the Earth
  system
•   Help determine the times of plant sprouting
  and growth
•   Help scientists improve weather and climate
  prediction
•   Help understand the potential for
  decomposition and weathering of soil
•   Compare with existing models and data sets for
  validation and for local detail

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Where To Perform the Gravimetric Soil Moisture
Investigation
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Taking the Gravimetric Soil Sample
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Taking Soil Moisture Depth Samples
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Drying Your Soils with a Microwave
1. Weigh your sample(s) 2. Dry on high power for
5 minutes 3. Weigh again 4. Dry on high power for
5 minutes 5. Weigh again 6. Repeat until
successive weights are within .2 g of each other
 Multiple Samples Can Be Placed in the Microwave
to Save Time The Soil Drying Oven is the
Preferred Method
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Frequency of Measurement

• GLOBE Soil Moisture Campaign
• At least one triplicate soil moisture measurement
  during the first 2 weeks of October (World Space
  Week and Earth Science Week)
• 4th week of April (Earth Day Week)
• At least 12 regularly spaced intervals
• Encouraged to sample the wet, intermediate and
  dry times surrounding major wet periods

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Soil Moisture Soil Water Content Formula