A horizontal approach: soil moisture and nutrient management
In the UK and East Africa, much research has been done to develop a standard way of irrigating hydroponic crops including roses, strawberries, raspberries etc.
Sentek's EasyAG probes, inserted horizontally into troughs, bags and pots are producing excellent results. EasyAG probes are big enough not to be disturbed by normal activities and can include 3 or 5 sensors in one bag. Therefore, it is much easier to tell whether one part of the bag is drying out.
Growbag strawberries are often irrigated up to 16 times per day and can grow quite well, even in full pick, for quite a few days without any signs of stomatal closing. The IrriMAX data indicated that the water use actually increases as the bag dries which perhaps demonstrates that the plant water use was being held back by too much water, probably depending on the substrate. It is a fact that strawberries taste better and have better shelf life when grown in drier conditions.
Using this method, it is vital that an efficient irrigation system is used to re-wet the bags once they have dried out. Peat especially is difficult to re-wet but small pulsed applications with little run off is possible.
Instead of applying blanket mixes of expensive soluble fertiliser, a soil sample when the water is switched off and again before re-wetting will give a good indication of what nutrients the plant requires.
TriSCAN information on the upper pane of the graph shows nutrient use with some accumulation at the edges.