The resilience of agroforestry in Twente: an interview with Martijn Aalbrecht, creator of ''De Voedselboss''

We sat down with Martijn Aalbrecht to talk about his project "De Voedselboss" near Hengelo. He told us about the differences between agroforestry and conventional agriculture, water resilience, using plant varieties from other regions and the surprising role of chickens in the forest.

How long have you been doing agroforestry and how does it differ from more conventional agriculture?

I think it's now been 12 to 13 years since I embarked on agroforestry. The oldest project was a romantic food forest with winding footpaths. Then a few years ago, I started my first agroforest with all the trees planted in rows.

The main difference between agroforestry and conventional agriculture is that in an agroforest you work with perennials (plants that live for more than two years and does not require annual planting) as compared to annuals (plants completing their lifecycle within one growing season). Perennials are resilient against drought and climate change and allow for more carbon storage beneath the ground. The harvest from perennials is also healthier because they have a deeper root system which allows them to pick up more nutrients.

Are there other benefits of agroforestry compared to conventional agriculture?

I think the main issue is that annuals, like maize and rice, are heavily dependent on climate stability. These staple foods are sensitive to the changing climate, so the harvest can suffer significantly in hot or dry years. With perennial systems, you have much more resilience against all those fluctuations.

And you can combine the agroforest system with animals, like cattle, chickens, or other livestock. As the climate becomes hotter and drier animals prefer shade, which they can get from perennial trees and shrubs, compared to grazing in the open field where annuals are grown.

Talking of animals, I know there are chickens in your agroforest. Could you please tell how chickens benefit the system?

Chickens benefit the system at multiple levels. I move them to a new spot in the forest every week where they eat various weeds and the first fruits that fall from the trees. These fruits tend to have a lot of insects and bugs in them. So, chickens eat the bugs, and it keeps the population of insects low. Because of this variable diet, they lay healthy eggs for us to eat. Finally, chicken manure serves as a fertilizer for the trees. It's a win-win situation for everyone!

Wow, this is a very efficient system! Talking more about water, which measures do you implement to be more water efficient, and do you adjust these measures depending on the climate each year?

I try not to use much water. When the trees are young, they need a little bit of watering now and then in the summer. But when the trees are 2 to 4 years old then they don't require water anymore. Since I pair trees of different heights in each row, smaller trees get a little bit of shade from the bigger ones. For tall trees I use tough species like elders and acacias and they serve as an umbrella in my system and create shade for the fruit and nut trees.

Do you use groundwater for your agroforest?

Yes, a little bit. I have a pump and an IBC (intermediate bulk container). The tank is holds 1000 liters, and I use it to water the young trees. So, it's a temporary system and after that, I don't need it anymore.

Do you change the variety of the plants that you put in a new agroforest depending on the changing climate and the region where the agroforest will be placed?

Normally I start with the pioneer species which usually do not provide any produce but help to establish the system. When these trees are two or three years old, I start selecting the fruit and nut trees.

Here in the Netherlands most of the soils are very sandy and dry. So, there are two things you have to think about. You must choose species with seedling rootstocks (the stump of a related species used for grafting). These rootstocks have more life force in them because they have created long roots in the ground looking to get enough moisture and nutrients.

Another important consideration is to choose drought-resistant varieties. I prefer to have smaller fruits, because they can stand the heat and drought, and are much healthier because they don't need all that energy to make big fruits. And the smaller fruits are super sweet and very tasty.  When the tree has larger fruits, you have to water it more, and we want to have system of trees that can take care of themselves.

Another aspect is with nuts. When I want to plant nut trees, like hazelnuts or walnuts, I try to look at varieties that don't come from our region. I choose varieties from Spain or France that are more drought resistant than the usual Dutch or German ones. Sometimes I use varieties from Eastern Europe like Poland or Hungary, because those trees can survive very cold winters, but also can stand very hot summers. So it's important to experiment with varieties that come from other regions of Europe because our climate is changing.

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