Next week is the official opening of a solar greenhouse at the Netherland's leading agricultural university that stimulates the climatic conditions of a typical greenhouse in China. A three-year project has just started where research will enable Dutch companies to align their technology with conditions in the Asian country, helping Chinese growers to increase their crop quality and yields.

The greenhouse uses solar energy buffered in a concrete wall, and will be used to grow vegetables like cucumbers and tomatoes.

“One of the main problems in China with the greenhouse types is that the humidity gets too high,” says Eric Poot project manager from Wageningen University. 

Making sure the first crop of cucumbers at the Dutch facility are kept at the correct humidity levels is vital. The first way to do this is by ventilation, which is controlled by a climate computer.

“Another way is to pump in air from the outside which is then heated to the right temperature via computer system," he says.

“One aspect for the control of humidity is the fact that we are using air from outside. When you have full-grown crops, you have a much higher humidity because of the evaporation of the crop.

“But when you pump air from outside, especially when you heat it up to the temperature, then you have a much lower humidity and it allows you to control the humidity in the greenhouse.

“Another very important aspect is that in China they grow most of the greenhouse crops in soil while we are using coco peat substrate and drip irrigation. This is also controlled by a computer and this is much more advanced than what they use in China.”

Another “big improvement” in technology applied at the Dutch greenhouse is a screen that sits inside for insulation.

“In China they use big blankets on the outside of the greenhouse and at night when it’s cold they roll down the blanket for insulation.

“While we are using screening technology, which is also used in glasshouses in the Netherlands, and this gives you much more flexibility.

“It’s not just about using insulation at night by stopping the cold from getting in, it also gives us an opportunity to use it when the sun shines, but the outside temperatures are too low. We have the benefits of the insulation, but because the screens are transparent, we also have photosynthesis.

The screens can also be used during hot summers to prevent the entry of too much heat from outside.

The cucumbers will be cultivated until July, followed by the second crop - tomatoes.

Side-by-side comparison

At the same time, another traditional Chinese greenhouse will be operating in China growing the same tomato variety. The research team will be monitoring and comparing production of both crops. 

“By growing at the same time and using the same variety, we can then make a comparison between the Chinese and Dutch production.

“We will monitor climate details, production data and all kinds of things.

“What is also important is the Dutch companies investing in this greenhouse, can use it for demonstration purposes. We have a lot of Chinese visitors in the Netherlands and we can show them what Dutch technology can do for their traditional greenhouses.”

Increasing yields is one of the main points of using high-tech solutions over traditional Chinese greenhouse methods and Poot predicts that volumes will significantly increase at the Wageningen facility.

He also points out this is an energy-efficient system.

“We need some heat for humidity control but we don’t use heat for heating up the greenhouse, it’s still an energy-efficient system, without the active burning of fossil energy.

“In China, they don’t have the energy infrastructure that we have in the Netherlands so it's important that we come up with concepts that they can apply.”

Dutch technology 'world's highest class'

The project is set up by Partners in International Business (PIB), a group of leading Dutch horticultural companies and knowledge institutes that are active in the Chinese market.

It aims to strengthen the position of its members - Hoogendoorn Growth Management, Ludvig- Svensson, Ridder Drive Systems, Hortimax, Delphy and Wageningen UR - in China by promoting their technology and demonstrating the advantages of using this technology and knowledge in China’s current horticulture sector.

PIB horticulture liaison Floriske Deutman explains how the consortium has joined forces to upgrade Chinese solar greenhouses.

“In recent years a lot of companies have come to the Netherlands to learn from the glass greenhouse technology because that is really considered the highest class in the world, the Dutch are well-known for this," she says.

“This consortium of companies wants to find new way of going forward by using the technologies in the glass greenhouse and making them applicable for the Chinese style solar greenhouse.

“The technologies include irrigation system, screens that they use especially for this type of solar greenhouse, climate control and growing on substrate.”

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