What type of measurement is the best suited for irrigation management?
Should you use soil tension, water content, ET (evapo-transpiration) or something else?
Well, it depends on what you are trying to achieve. If your goal is to manage water volumes, supply, pumping capacity and so on, water content and ET are good approaches. On the other hand, if your goal is to manage plant stress, optimize plant growth, agronomic results and profitability, soil tension is the way to go. The rest will follow.
Water movement in a plant or tree – from uptake by the root system to evaporation by the leaves – are dictated by pressure – or tension – deficits. They are driven by tension and the laws of physics. Soil tension is directly linked to the plant’s metabolism and can allow for anticipating water stress, in
turn avoiding it before it happens.
The implications of this are not minor. A slight change – often unnoticeable in water content can lead to a large change in sol tension, that could lead to crop stress.
Hence, while this situation could go unnoticed using water content probes, it is obvious when soil tension is measured.
Tension doesn’t have to be calibrated for every soil type; it is not influenced by soil salinity and is the most straightforward
and simple irrigation management tool.