by Andreas Hunkeler
Due to the longer dry periods and higher average temperatures, trees require more and more additional irrigation. Especially in cities (see text about increasing problems of urban trees).
In its blog, WWF Germany therefore calls for people to water trees in their own city: https://blog.wwf.de/baeume-giessen/
The WWF gives three recommendations for watering trees:
- It is best to water early in the morning or after sunset
- After a long period of drought, the earth is almost water-repellent. Please water first and wait until the water has seeped in. Otherwise the water will simply run off and the tree will benefit from it.
- At least ten liters of water should be poured per tree, preferably once a week.
I would like to affirm these points and say something else:
- The trees are ideally watered when the sun is not yet burning heavily on the ground. There are two reasons:
At lunchtime, the air temperature is often so warm that some of the irrigation water evaporates on the surface of the soil and thus cannot reach the roots.
2. The water droplets act like small burning glasses and can cause severe damage to the finer tree roots in strong sunlight.
- Moistening the soil before watering is important but is often neglected. Dry earth is hard and the water flows away without reaching the deeper soil layers. It takes quite a long time for the soil to be moist enough for the tree to use the water.
- In the forest, for example, a 150-year-old beech evaporates up to 500 liters of water every day. With its 800.000 leaves, it also takes up to 24 kilograms of CO per day2 which corresponds to a journey of 150 kilometers in a small car. And at the same time, this beech tree produces around 11.000 liters of oxygen every day and can therefore supply 26 people. So I would say that a tree needs a lot more than ten liters of water a day. Irrigation of at least 70 liters of water per watering cycle is ideal. Depending on the weather, several watering courses per week are required.
Important: the right equipment
Watering with a hose and watering can is not ideal for trees because too much water comes too quickly. Most of the water washes away and does not even reach the roots.
Many cities have already recognized the potential of the baumbad tree watering bags and are giving them away to their tree sponsors. The combination of irrigation bags with watering sponsorships is ideal!
The bags are filled quickly, the water can be measured and then slowly trickles into the ground. This makes it easier for the sponsors to keep track of how much water they are giving the trees, depending on the needs or recommendations of the municipal companies. The tree can absorb the water better and the tree sponsors also save water.
And watering with the bags also corresponds to the recommendations of the WWF:
- Because the water is in the bag, it evaporates much less than it does on the floor. The bags can be refilled and then they transfer the water drop by drop to the soil layer. The baumbad watering bag collapses as soon as it is empty and covers the ground like a layer of mulch. This protects against solar radiation and evaporation.
- The most important point to work with irrigation bags is that through this drip irrigation the water is released so slowly that the Bodes can actually absorb it. The earth layer is slowly moistened for six to nine hours and the water gets into the deeper layers. This means that there is much more water available to the trees.
- With a watering bag you can pour 75 liters at once. That's an ideal amount for a tree.
By the way: Baumbad has a special offer for cities that want to equip their godmothers with watering bags. If you are interested, you can simply contact us.
Graduated social and cultural anthropologist with a focus on sustainable and participatory green space design in cities.
My vision is to bring together: people and trees, nature and culture, population and urban authorities.
If you have any questions, suggestions, interesting stories or exciting knowledge on this topic, please write to me:
firstname.lastname@example.org. I'm looking forward to your message.