Circular Horticulture

Greenhouse horticulture is a very efficient production sector. For example, modern companies increasingly recirculate their fertilizers and water, and no nutrients or crop protection products ends up in the surface water. The next step is a truly circular sector. Alexander Boedijn (Team Circular Horticulture): “Circularity is a powerful instrument to achieve sustainable greenhouse horticulture.”

In the Netherlands, Europe and worldwide, efforts are being made to transform to a circular economy. In other words: an economy in which as many sustainable, renewable raw materials and products as possible are used, reused and last in cycles for as long as possible. For example, the Netherlands wants the use of primary raw materials (minerals, metals and fossils) to be halved by 2030, and for the economy to be completely circular by 2050.

Boedijn: “That means that many sectors have to take major steps.” This also applies to greenhouse horticulture. This sector is already extremely efficient in many respects, which means that raw material consumption and environmental impact continue to decrease.

Dependence on non-renewable raw materials

But efficiency on your own farm is not enough for a circular sector, according to Boedijn. Even the most efficient greenhouses depend on linear chains and non-renewable raw materials. Examples are natural gas for energy, CO2 and nitrogen. Or phosphate rock (P) and potash (K) that are extracted from mines to make fertilizers. Basalt and peat for growing media. Crude oil for plastic.

The natural reserves of these raw materials are finite. Above that: the current way of producing and consuming leads to the loss of raw materials and a negative impact on the environment. In addition, greenhouse horticulture still produces waste streams with low-value applications.

Challenges for greenhouse horticulture

Boedijn: “Greenhouse horticulture has everything it takes to become a circular sector. But there are still some challenges, like: less dependence on primary (finite) raw materials, no more waste flows, producing valuable residual flows, upcycling our own and external residual flows, and reducing harmful emissions to soil, water and air. And at the same time, greenhouse horticulture must continue to supply healthy, high-quality products.”

Our contribution to circular greenhouse horticulture

Wageningen University & Research contributes to this through our expertise and network in areas such as fertilizers, growing media, CO2, water, biomass, plastics and crossovers. WUR is active in the following areas:

Identify alternative raw materials and sources

The greenhouse horticulture sector is still dependent on all kinds of mostly finite, primary raw materials and sources. To this end, we research more sustainable alternatives by closing the loop. We look at where there are ‘leaks’ in society and how raw materials can be recovered from them. For instance, we investigate whether phosphate from sludge ash (from sewage treatment) can be used instead of importing phosphate from mines in Morocco and China.

Quantifying material flows and mapping quality

What does it mean to work with a new material, a new substrate, a new CO2 source or an alternative source of water? Is it safe for the crop? There are often all kinds of questions about sustainability, but the basic knowledge is lacking. We map new materials on a quantitative and qualitative level and draw up material balance sheets to build this knowledge.

Testing, integration and evaluation of new technologies

For all material flows, there are new technologies that can be tested in our greenhouse facilities in Bleiswijk. We test and evaluate these technologies for e.g. efficiency and evaluate whether it is indeed a valid alternative source for resources in the greenhouse horticulture sector. One example is a new CO2 machine that draws CO2 from outside air.

Redesigning systems

Businesses are keen to become more sustainable or switch to more sustainable alternative materials, but also want to know what their sustainability investment will yield. We can help by comparing and
evaluating sustainability solutions and directions within the circular playing field. LifeCycle Assessment is one of the tools we use for this purpose.

The Circular Horticulture programme is based on the material flows entering and leaving greenhouse horticulture and the interplay of these flows.