Research cooperation at Monreberg 🧪🤝📚
The Sweet Chestnut Dislikes Waterlogging 🌰💧❌. This is one reason why it is not commonly found everywhere in the Lower Rhine region 🏞️ As part of a research cooperation within our Agroforestry Living Lab 🌳🔬, eleven trees were planted on Monreberg in Kalkar in November 2024 🌱
The planting marks the first step toward establishing an agroforestry system, with the sweet chestnut tracing geographical and historical paths reminiscent of the Romans. The Romans established military camps, settlements, roads, and the Limes border wall in the Lower Rhine region, which they called Germania Inferior. Close to the sweet chestnut planting site was the Roman cavalry camp Burginatium. It is believed that the Romans introduced the sweet chestnut to Germany from the Mediterranean region.
Planting as a Climate Tree
The botanical name of the sweet chestnut is Castanea sativa. It thrives in Germany’s warmer and milder regions and is expected to play a more significant role in the future due to climate change. This light-demanding tree, more widespread in Spain, southern France, and Italy, is better suited to withstand heat and drought than some native trees in Germany.
Positive Attributes of the Sweet Chestnut
High Nutritional Value for Humans:
Sweet chestnuts, botanically classified as nuts, are rich in starch, B vitamins, vitamin C, and minerals. Their energy density is comparable to maize or potatoes. Besides their caloric value, sweet chestnut trees provide additional environmental and agricultural benefits.Promotes Biodiversity:
The flowers provide nectar and pollen for insects such as bees, hoverflies, and beetles in summer. Their fruits, also known as chestnuts or marrons, serve as an essential food source for mammals and birds from autumn onward. Additionally, the bark of older trees, with its elongated cracks, offers protection for insects.Enhances Soil Quality:
The leaves of the sweet chestnut decompose quickly, contributing to nutrient-rich humus and improved soil water retention.Beautifies the Landscape:
Known for its vibrant autumn colors, the sweet chestnut also delights nature lovers with its long yellow catkins and white-green flowers that appear in June, accompanied by a pleasant fragrance.
Planting for Research
Anna-Lea Ortmann, a doctoral researcher on our Agroforestry Living Lab team, oversees the cooperation. This involves a variety trial: five saplings from a crossbreed of Dorée de Lyon x Marsol and five trees of the cultivated Dorée de Lyon variety were planted.
“The Dorée de Lyon sweet chestnut is considered adaptable, and previous experiences in Germany suggest that its fruits can ripen well here,” Anna-Lea explains. “Additionally, its chestnuts are known for their good storage qualities.”
The planting of both saplings and pure cultivated varieties serves a purpose. Saplings are grown from seeds, while cultivated varieties are grafted—a process where a young shoot from a variety tree is joined to a rootstock. The former is called “generatively propagated seedlings,” while the latter is referred to as “vegetatively grafted varieties.”
Differences between saplings and cultivated varieties are expected as the trees grow. Cultivated varieties develop smaller crowns and are generally less vigorous than saplings. On Monreberg, the cultivated and seedling varieties were planted alternately, 8.5 meters apart, to enable direct comparison.
To protect the roots, galvanized wire baskets with a mesh width of 30 mm were installed to a depth of 70 cm.
The soil structure was also apparent during the digging. Beneath a thin topsoil layer, sandy soil dominated—a result of the terminal moraine from the Saale glaciation. While this benefits the sweet chestnut, which struggles in waterlogged soils, the rapid water drainage of sandy soil necessitates irrigation during dry summers, especially for young trees with underdeveloped root systems. Proper water supply remains crucial for fruit development and yield—a focus area in Anna-Lea’s research.
Additionally, the cultivated Bouche Rouge variety was planted as a standalone tree. “An exciting variety with positive results at other sites in North Rhine-Westphalia,” Anna-Lea reports. It has sufficient space to grow into a large tree, and nearby old sweet chestnuts will aid pollination.
Planting for Flora and Fauna
Jürgen Janssen, the Agroforestry Living Lab’s cooperation partner, is a trained farmer who leases his farmland. Adjacent wildflower fields provide blooming habitats and refuges for wildlife. Early on, Jürgen expressed interest in shaping the landscape. “I’ve disliked the openness of these fields since childhood,” he recalls.
The family’s farm and surrounding woods are home to many old sweet chestnut trees, making it natural to plant more in the new area. Jürgen aims to harvest and potentially market the chestnuts in the future. Until then, the fruits will serve his family’s needs.
Sustainable Food Systems Research Centre
Marie-Curie-Straße 1
47533 Kleve
Deutschland/Germany