Shocking revelation, the sun heats up the soil!!

Soil temperature on sunny days.

Did you know that the sun will heat up the soil.... Yeah no kidding.
While this is common sense, this research is giving us a more detailed look into conditions in the soil and is showing us just how much of a difference there is.  As would be expected, the vegetable plot in the sun heats up more compared to the perennial plot in the shade.  Additionally, deeper into the soil profile will have cooler and more moderated temperatures.  Below is a snapshot of data from early June when it was warm and sunny- with some details and insights.

The graph above was pulled off of ZentraCloud and shows the soil temperature over a couple of days.  This shows that as expected, the deeper you move into the soil, the cooler and more even the temperatures.  

Perennial area in shade with higher humidity

• In the shade temps are cooler and don't fluctuate as much
• Between 4 and 8 inches, there is a daily fluctuation of about 6-8 degrees.  Specifically from 68 to 73 degrees.  
• Temps peak between 7pm and 10pm
• It take about 10 hours to heat up
• There is only a couple of degrees difference between 4 and 8 inches
• The night temperatures stay warmer than the Vegetable bed  
• Higher relative humidity
• Closer to creek
• More canopy
• More tree cover

• The sunny area in the vegetable bed has more drastic changes



Vegetable bed out in open with lower humidity at night

• At 4" the soil temp jumps from 66 to 84 degrees
• It takes only 4 hours to reach high temps
• Temps peak between 2pm and 3pm
• At peak there is a 10 degree difference between 4 and 8".  73 vs 84 degrees.
• Gets cooler than the perennial plot likely due to humidity
• More heat is lost at night
• Little plant canopy
• Out in the open  

We have data on cooler days and can also see the 4" readings drop occasionally when it rains.  More on that and other measurements later.

Kevin

Sensor Installation Day

Sensor Installation Day:
May 24 2019

Kevin and Alexis installing at Site One. 

The CHSTR team selected two sites at Ball Horticulture for this study. Our first site is located near a creek, in the back perennial gardens of Ball. We chose this site based on its potential for changes in water events, such as flooding due to high rain fall. This bed consists of a planter mix created by Midwest Trading, complete with in-ground irrigation provided by Ball. Studying this site allows us to understand the practical application of our product, as well as gives us insight on the use of irrigation systems.

Kevin and Michael installing at Site Two. 

Site two is a vegetable bed, located on higher terrain. Similar to site one, this vegetable bed consists of a planter mix and in-ground irrigation systems. We chose this bed in order to understand the application of both the planter mix and irrigation systems in an area that would be considered "more dry" or "normal" in comparison to site one, which is more likely to be effected by water events.

Teros 12 and Teros 21 in Site One. 

Both sites consists of various research instruments, placed at the same depths. Each site contains two Teros 12, two Teros 21, One T8 Long term monitoring Tensiometer, as well as one ZL6 Cloud data Logger. The  Teros 12 are used to measure the moisture within the soil profile, as well as the temperature. These instruments are placed 8 Inches into the bed, close to the base, as well as 4 Inches in the bed, the midway point of the bed.  The Teros 21 measures the water potential within the soil profile. These are placed 8 Inches at the base of the bed, as well as 4 Inches at the midway point of each bed.

The CHSTR Team.

The T8 Tensionmeter measures the matric potential and plant available water within the soil profile. This is placed 6 Inches within each bed. The ZL6 Cloud Data Logger is placed directly at each site. This allows us to record live data in 5 minute increments on all of our research instruments. The information updates every hour on a cloud platform. The CHSTR team had a great day spent out in the field and we are so excited to see what this trial brings! Please see more sensor installation pictures below!

Soil Water Potential Sensor Research

The beginning of a new engineered soil research program in Chicago 

The CHSTR team has begun a new research program into the water status in engineered or manufactured soils.   We are looking at the matric potential, or more specifically the plant available water in a manufactured planting media.  This is the first phase in what will be a long term extensive research program to study manufactured or engineered soils and their hydrology.

We want you to think of a sponge.  Soak it with water and that is similar to saturating the soil.  As you start to squeeze the sponge, water comes out until you can't get any more out even though the sponge is damp.  This is how the root system in a plant works as well.  It will pull water out of the soil until it reaches a point where it can't get anymore out.  Simple enough right?

The challenge we run into with manufactured soil environments (a blend of ingredients put in place in a landscape) is that we can estimate total water in a soil, but it is difficult to measure how much is available to the plant.  The measurement of how tightly the water is held to the soil is called matric potential. We are looking at using a combination of in field moisture sensors along with matric potential sensors to measure how much water is available to the plant in the soils we are evaluating.  The key here is that the matric potential sensors are a direct measurement of how tightly held the water regardless of what type of soil we look at.

From this we can look further into how these blends are designed, what materials to use and how to optimize drainage and porosity with plant available water in an urban landscape.

We look forward to providing updates through the summer and posting some of our findings along with some background into the technical side of soil physics and hydrology as it applies to landscape horticulture.

CHSTR Team