Ask the Agronomist: Does Soil Type Affect Water Movement?

soil type water movementSoil types and structure play a large role in infiltration rate. Hortau’s tensiometers, which do not need to be calibrated based on soil type, give growers visibility into the soil so they can observe water movement though the profile in real time.

A question we receive a lot is why growers sometimes see water movement for 24 hours or more following an irrigation event, but much less time in other instances at different locations.

A grower recently reached out to us with the question below followed by a response from Hortau Director of Grower Support, Ben Smith.

Question: “After you shut off the irrigation, sometimes you see that water continue to move through the profile. Do you see different soil types that water moves through differently in say sand versus clay?”

Hortau Director of Grower Support Ben Smith had this response:

Water moves through soil a little differently based on soil structure.

Basically, there’s two major forces. There’s gravitational movement and matric potential that moves water through the soil.

Clay heavy soils tend to move it through capillary or matric potential, which is much slower moving. Because of that, in some of these heavier soils you’ll shut off the water and see movement for another 24 hours.

The great thing is, this movement becomes very reproducible. If you start irrigating at the same spot for the same amount of hours, you’ll get very close to the same reaction.

So, with a little trial and error you can start to nail irrigations and manage water movement correctly every time.

Key Takeaways:

  • Soil structure affects water movement through the profile
  • Two forces act on water movement in the soil: gravitational and matric
  • Heavy clay soils move water through matric potential, which is slower
  • Water can continue to move through heavy clay soils for up to 24 hours after an irrigation
  • Results are reproducible and visible with Hortau’s real-time soil tension monitoring system

To learn more about Hortau and its irrigation management and scheduling services, contact us today or check out this presentation on Hortau’s precision irrigation management platform.