I have been planning to buy a few plant sap flow meters for testing. I hope to track and graph plant transpiration based on climate, air flow velocity, PPFD, plant age, growth phase, dry backs, and nutrient profile. Flowers transpire much less than leaves, so I expect a reduced transpiration rate in mid-to-late flowering vs. veg phases. Although veg plants are smaller with less leaf surface, so the difference in transpiration may be reduced.
But with the new Hydrobuddy version, the plant sap flow meter data just got much more interesting.
Interesting, I’ll play with it tomorrow. The approach reminds me of Torsten Ingestad and Demand Driven Fertilization. Most people’s heads are going to spin when they use the UNC numbers and see that the fertigation solution has more N than K.
All of them show K less than N, and this is from the blog:
The above implies that values should not be used without considering the context and that this context might be much more important for some nutrients, for example micro nutrients, than for other elements, for example K and Ca, for which the availability windows and plant uptake are much more straightforward. The plant characteristics should also be taken into account. While a leaf tissue derived approach might only require 50 ppm of Ca in a lettuce crop, we know we need to feed more due to the poor water transport of this plant into new leaves.
Second, the approach assumes that all we care about is leaf composition. This is a perfectly fine if we are growing leafy greens, but if you’re growing a tomato plant, the composition will be heavily split between leaves and fruits as soon as flower pollination ends. For this reason, the nutritional needs of other important tissues – such as sink organs – should be considered very carefully when following this approach. In the case of tomatoes, this might mean feeding substantially higher levels of K, as this element has a much higher concentration in fruits than it has in leaves.