You can help trees during drought by watering them or by helping them search for water themselves

ARTICLE

MARKET & CURRENT AFFAIRS

Hein van Iersel, Wednesday 27 August 2025

65 sec

In an article in a scientific journal, Mattheck presents the idea of supporting trees suffering from drought with a number of vertical drillings, filled with a mixture of gravel and biochar (Terra preta).

Gravel column

During prolonged drought, the upper soil layer often becomes so hard that rainwater hardly penetrates. German tree researcher Claus Mattheck proposes drilling deep holes (at least 20 cm in diameter) at strategic spots around the tree, down to moister layers. The holes are filled with a mixture of gravel and manure-enriched biochar, with the biochar completely filling the spaces between the stones.

Imitating nature

The gravel columns provide air, water and nutrients, and stimulate roots to grow into deeper layers. This way, roots move away from the dry top layer and still find water during hot periods. Unlike watering, this approach mimics the natural growth of trees in rock crevices and deep sand layers.
The method can be applied to both new plantings and existing trees, with attention to cables, pipes and mechanically important roots. In parks and gardens, feasibility is greater than in an urban environment, where space and depth are often limited.

Pilot

Mattheck emphasizes that it is a hypothesis that has not yet been tested in urban tree care. The idea is based on observations in nature and on the traditional application of biochar by indigenous peoples in the Amazon region.

Boomzorg Scholar

Boomzorg Scholar is a new initiative of the trade magazine Boomzorg, in which we make articles from a scientific journal available to an audience that normally does not read these journals, by translating and popularizing one article per issue. This time it is a story by Claus Mattheck, Siegfried Fink, Klaus Bethge, Karlheinz Weber and Iwiza Tesari with the title 'A Strategy to Help Trees Suffering from Drought' from the Arboricultural Journal (2021, 43:4).

This article was previously published on 4 September 2025 on the website of Boomzorg.

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