Horticulture within the Circular Economy: what goes in and comes out of a greenhouse?

With greenhouse practices focused on circularity, the horticulture sector can increase their contribution to the Sustainable Development Goals formulated by the United Nations. The core idea behind this is that all material flows could be reused instead of relying on natural reserves for resources. But what does this really mean: which resources and materials does a greenhouse actually use? The Greenhouse Horticulture and Flower Bulbs Business Unit of Wageningen University & Research is investigating this.

Characteristics

A greenhouse has many incoming and outgoing material flows, such as water, fertilizers, CO2, plant material, substrate, paper and cardboard, plastics and plant protection products. These flows each have their own characteristics. For instance: water. It enters the greenhouse as a liquid (irrigation water), and leaves the greenhouse as a part of the product (such as a tomato), as evaporation (through the crop) and as a residual flow (such as discharge water).

Though various research disciplines focus their studies on these material flows, there is not yet an overarching quantitative or qualitative overview for greenhouse horticulture within the framework of a circular economy. That is why WUR is developing a method to map the most important flows. A range of sources are used for this, such as various databases, the KWIN and crop models.

Arrows and diagrams

By analysing and combining the gathered data, researchers can create Sankey diagrams. Such diagrams contain arrows and their width shows how large the flow in question is and it becomes clear at a glance how a material flow moves through a greenhouse horticulture company.

Not only quantity of a material flow is important, but also the impact on the climate and environment. The approach will therefore not only have to provide quantitative insights, but also qualitative insights. In addition, the 'end point' of the arrow is important. For example: can a material be reused in the same company (whether or not by arranging processes differently), in another horticultural company or even in another sector? And what are the bottlenecks for either of these?

Two phases

In the first phase of the research, WUR analyses the material flows for three different crops in the Netherlands: tomato, gerbera and orchid. Based on this work, the approach can be applied to more products and for more countries and regions. In the second phase, the research will focus on redesigning processes to solve the identified bottlenecks. It also devotes attention to cooperation and exchange of flows with other sectors. The knowledge that is created within the project must contribute to a greenhouse horticulture within a circular economy that is clean, efficient and connected.

The project runs until 2022 and is part of a knowledge base research program within WUR that is funded by the Ministry of Agriculture, Nature and Food Quality.