Why we don't irrigate our farmland
Updated: Aug 28, 2020
It's easy to think that if you have land with crops or trees that bear fruit, it's a must to water this land. Especially in the Alentejo, where the climate is very hot and dry in the summer, you might think it's impossible to grow anything without watering. Yes and no.
We are lucky in many ways because of the topography of the land. We are in a valley and surrounded by a small mountain range. This means that the valley is a natural water basin. We don't have any visible lakes but deep under ground is a big water reservoir.
Because the trees here were never watered artificially over the last centuries, they have grown strong and deep roots to reach the water reservoir. This is what allows them to survive the dry period between June and September. Plants that are more surface level with more shallow roots don't survive this period, which is why the grasslands here look brown and barren during the summer.
What if we watered the lands?
If these lands had been watered by man in some way, the trees would have developed differently with roots that were closer to the surface. If, for some reason, the irrigation stopped at some point, the trees would then struggle to survive.
Watering systems take the water from somewhere. Often it takes the waters from the ground water or water reservoirs. The water is then sprayed on the lands, which we might think is a good idea because it will fall down into the ground again. However, in reality, about two thirds of the water sprayed evaporates in the process and is lost to these lands. Granted, they will re-join nature at some point in the next rains but those may not fall on the same lands.
It's because of this that many countries are starting to forbid irrigation. In Switzerland for example, organic or bio producers need to demonstrate that when using irrigation, they are not depleting the ground waters.
For us, it is a conscious choice to preserve the ground waters and aquifers that are part of the land. Just as we are simply taking care of this land for the time being, we also have a duty to take care of the ground water that is below the surface.