Dutch innovation – drying horticulture seedlings with potting soil utilising geothermal heat
Dutch horticulture supplier Van der Knaap in the Netherlands has set up an innovative drying solution to dry plugs used to grow seedlings in the horticulture industry. The plugs are dried sustainably utilising geothermal heat.
Dutch Van der Knaap group of companies recently opened a drying area for Obturo® plugs. Plugs in horticulture/ greenhouse operations are small-sized seedlings that are grown in seed trays filled with potting soil. Van der Knaap is a supplier to the global horticulture industry with rooting and growing media products. The plugs by van der Knaap are used to commercially grow vegetables and bedding plants in greenhouse operations. The plugs by Van der Knaap are excellent for drying and then rewetting. The advantages are numerous. The dried plugs have a longer shelf life and much lighter for shipping/ transporting them to customers and operations. To achieve this the group has developed a solution that utilises geothermal energy to dry these plugs with geothermal energy, clearly a great sustainability story.
Since 2018, the group’s innovation centre ‘de Kas’ in Honselersdijk in the Netherlands has been connected to the geothermal energy network ‘Aardwarmte Vogelaer’. The innovation centre is certainly not a major consumer, which means that some of the geothermal energy is also available for other applications. The return water (i.e. after being used in our cultivation greenhouses) is sufficient to heat the required air for the drying room through a heat exchanger. Because we use the geothermal energy efficiently, we return cooler water. This increases the efficiency of geothermal energy consumption.
To dry the plugs, they are placed on trolleys in a separate cell. The moisture is absorbed from the plugs with warm and dry air. After delivery, the plugs can easily be returned to the correct moisture percentage. Obturo® plugs absorb moisture with ease.
The main advantage of dried plugs is their increased shelf life. Living organisms such as bacteria can consume nitrate (NO3) in plugs that are kept moist for a long period of time in sealed packaging. This happens especially when the oxygen present has been consumed by the presence of aerobic bacteria. When this happens, the bacteria will feast on the oxygen that is bound to NO3, with N eventually escaping as nitrogen gas. In addition to this process, other important nutrients, such as calcium and magnesium, also disappear over time. However, drying the plugs halts these processes and the nutritional elements will not or hardly be consumed. This allows the plugs to be stored and transported without loss of quality.
Obturo® plugs can be tailored to customer requirements. The size, tray, cutting holes and potting soil mixture can be adjusted in consultation. In this way, Obturo® offers all the flexibility to perfect the cultivation process.
Source: van der Knaap