November 07, 2018
Can there be such a thing as a “hot new metric?”
We’ve been hearing (and reading) innovative growers talking about the relevance of vapour pressure deficit (VPD) for a while now. We’re seeing the difference monitoring VPD has made to our customers’ crop performance, and we’re always glad to see the word spreading. Earlier this week, an article in HortiDaily provided a nice breakdown of why this metric is so useful in crop management.
As the article points out, VPD “is used by growers to assess how dry the air is at a given moment. If the air is too dry, photosynthesis will stop in order to protect the plant from exhaustion.” If there is insufficient moisture in the air, there is a risk of crops halting photosynthesis during key hours of daylight. In other words, VPD enables growers to make the most of sunlight for plant productivity.
Growers and researchers alike are excited about VPD. But what is it?
According to Michigan State University’s Heidi Wolleager and Erik Runkle, “vapor pressure deficit is the difference between the amount of moisture in the air and how much moisture the air could potentially hold when it’s saturated.” Put simply in Maximum Yield, “VPD combines the effects of both humidity and temperature into one value; it’s basically a measure of the drying capacity of the air, which in turn drives transpiration, an essential plant process.”
VPD is a key metric for maintaining optimal plant biomass and yield, and the right VPD is central to preventing mold and disease, avoiding poor nutrient uptake— particularly of calcium. VPD measurements help growers calculate crops’ water requirements, and according to Maximum Yield, can help prevent “negative effects on plant growth including reduced photosynthesis, reduced fresh weight yields, plant stunting and physiological problems such as leaf curl or burn.”
According to Michigan State research, VPD is a more useful metric than relative humidity. Wolleager and Runkle emphasize that because VPD is independent of temperature “when measuring plant transpiration and water loss, it provides greater insights than temperature and relative humidity on their own.” Read more of their findings here.
Capturing VPD (and other metrics) with 30MHz technology
30MHz tech has always been designed with growers’ needs at the forefront. Developed with input from growers, the pointed microclimate sensor can capture plant temperature of individual crops, ambient temperature and relative humidity (RH). With the power of the cloud, though, we can anticipate “hot new metrics” like VPD based around these measurements.
The ZENSIE platform is designed to make the most of customers’ agridata. With the data captured by the pointed microclimate sensor, calculations in the cloud can provide insights on dew point, vapour pressure deficit (VPD), absolute humidity (AH), humidity deficit and the absolute difference between air temperature and dewpoint.
And we’re adding new calculations, based on customer needs– that’s the power of a cloud platform.