I have noticed a trend in recommending plant-based sensors or gadgets (e.g. dendrometers, stem micro-variation sensors) for irrigation scheduling by AgTech companies. This begs the question, “how to know if these technologies even work?”
This is a long discussion, but there are questions you can ask these companies that determine if their solutions are worth investing in:
1) What models or algorithms they’re using for decision-making? Raw data is useless.
2) How do they normalize their plant-based measurements? Plant-based measurements are a function of microclimate (air temp, relative humidity, etc) and soil water content. If temp changes, they do too.
3) How do they establish the wet and dry thresholds? This is required to determine when to irrigate, how long and when to stop.
4) At what time of day, they carry out measurements? If real-time measurements are provided, what time of day is the basis for decision-making? Plant response to stress is time-dependent. In many crops, midday measurements are not correlated with soil water deficit!
5) How does their method distinguish between diseased, and healthy water-stressed plants?
6) Are their sensor measurements temperature-compensated? All sensors have temperature sensitivity, some more, some less. Sensors exposed to larger temperature fluctuations (like those exposed to air flow) are expected to show higher measurements errors.
It’s also good to know that not All plants are created equal, meaning that plant-based measurements don’t work in all crops. Ask them for case studies…