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Soil Percolation Test

A project log for Vinduino, a wine grower's water saving project

Monitoring soil moisture at different depths to determine when to irrigate, and - more importantly - how much water is needed. Save 25%!

reinier-van-der-leeReinier van der Lee 08/17/2015 at 03:042 Comments

Last weekend before the Hackaday Prize entry closes. And what a weekend it was!!

With these extreme temperatures, reaching 110F (43C), each grape vine consumes 4 gallons per day.
Irrigation is set to replenish the daily use of the vines in the coming week.

I tested soil percolation speed, and general functions of the system, by applying a generous amount of water and log the time for the sensor resistance to respond.
Interestingly, it takes 5 hours for the irrigation water to reach the sensor at 2 feet deep, and it takes nearly 24 hours for the water to fully saturate the soil at 2 feet depth. Of course it will taken even longer for the water to percolate farther down to the sensors at 4' and 5'.

Results may vary, depending on the type of soil, and installation depth of the sensors.

Because of this, you cannot use a single sensor in the active root system to act as an on/off controller for irrigation. By the time the water reaches the sensor, too much water would have been irrigated.

Will keep tracking the soil response to irrigation. This is important data for building an automated irrigation system.

Also made the required 4 minute video for the "Best product" contest category.
Good luck to all participating hackers!

Discussions

Reinier van der Lee wrote 10/19/2015 at 04:34 point

Hi Christoph, after observing events for a while now, I think there are two things to consider for a simulation model. For irrigation dripper the depth of irrigation depends on the quantity of water. Irrigation moves down AND spreads out until the movement stops. When it rains, there is a uniform distribution of water over the whole soil surface, and so there is only downward movement. As I observed, rainwater shoots right through the soil, and reaches the 5' depth sensor just  shortly after the 1' sensor triggered.

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Christoph wrote 08/17/2015 at 07:14 point

When did you apply the water? August 15th, 6:00? The diagram doesn't show that. With additional data from the two sensors further down it might be possible to derive a simulation model.

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