Achillea millefolium

During with the nice and persistent heath we were experiencing in Belgium, we started our drought experiment on the university campus.

With the help of some very welcome extra hands, we put ten by twenty meters of plastic foil over our greenhouse to keep out the rain. The lowest meter stays open to allow the wind to flow through, otherwise it will start heating up as well (like a ‘true’ greenhouse would).

It was our final chance to start the drought, as our plants were growing crazy fast and establishing very well within our experimental gaps. If we would wait much longer, they would grow too strong to experience much damage from our experimental drought.

Measuring light on the soil surface

By now, half of the gaps have suffered a persistent drought of one and a half week. Plants in the gaps clearly slowed down their fast growth, compared to those that generously get precious water from us once every two days.

White clover

 With the thermal camera, we closely monitor the temperature in our gaps, especially now, during the drought. On a nice day, temperatures on the soil surface easily rise above 40-45 °C.

But not all plants seem to mind the heat that much. If their roots reach deep enough to maintain access to the precious soil water, they can keep their temperatures low, often staying more than ten degrees below the environmental temperature.

Control gap, with happy dandelions

But with persistent drought and hot temperatures, the soil water will get increasingly difficult to access, making their life a lot more difficult. I’ll keep you updated!