SFM1 Sap Flow Meter

Irrigation managers face two questions: when and how much to irrigate. A new video, available on YouTube and with a weblink below, explains how sap flow sensors can be used for irrigation scheduling and dosing.

Sap flow sensors measure crop water use or transpiration. With a sap flow sensor, it is possible to determine how much water a crop is using. Using simple accounting and a water budget, irrigation dosing, or the amount of irrigation, replaces the amount of water used by the crop either through rainfall or irrigation. This approach balances the budget.

When to irrigate, or irrigation timing, can also be determined with a sap flow sensor. A reference, or comparison, is required to compare the crop water use against a standard. The best standard is evapotranspiration (also known as ETo or Penman-Monteith FAO56 reference evapotranspiration) or crop evapotranspiration (ETc). When tree sap flow declines relative to evapotranspiration then irrigation should commence.

The video below discusses these and other concepts in detail.


video: irrigation management with sap flow sensors