According to the latest estimates, by the year 2050 there will be about 9.2 billion people living on the Earth – around 2 billion more than today. In order to be able to secure food supplies in the light of this rapid increase, scientists around the world are looking for innovative solutions for the agricultural industry.
Among them are the scientists at the Hohenstein Institute in Bönnigheim, who, together with the roma-Strickstoff-Fabrik Rolf Mayer GmbH & Co. KG (Balingen) and the State College of Horticulture and Agriculture (Stuttgart-Hohenheim), have developed heating textiles for use in plant cultivation. These are placed around the roots of the plants and so supply them with targeted warmth.
The temperature around the roots is a crucial factor in germination (seeds), sprouting (bulbs), plant development (generative phase) and plant growth (vegetative phase).
That is why, when these high-tech textiles are used in the greenhouse, they help save energy, because the ambient temperature can be greatly lowered with no reduction in yield. Furthermore, the heating elements can be used to control the vegetative phase very accurately to optimise the harvest. Last but not least, because the heating textiles provide safe and reliable frost protection, they enable more tender plants to be grown even in difficult climatic conditions.
The research project, sponsored by the Central Innovation Programme for SMEs (ZIM), was based on an extensive list of specifications in order to meet the various requirements. Among other things, the textiles being developed needed to have a stable temperature profile, permit variable heating from about 5 0C to 40 0C, be structurally resilient and water-resistant and not degrade in soil (anti-fouling).
To achieve these objectives, the project partners investigated the suitability of various knitted heating fabrics. The basic material for the fibres was always polyester, in once case galvanised with silver to make it conduct electricity. In a second material, conductivity was achieved by knitting a stainless steel yarn into the fabric. In the third test material, two stainless steel threads entwined in a criss-cross pattern provided the electrical conductor. The three fabrics were subjected to various textile technology tests at the Hohenstein Institute. These included not only mechanical stress testing but also tests to assess the resistance of the textile to destruction by microorganisms.
Naturally, the Hohenstein researchers paid particular attention to analysing the heating capability of the textiles. This was judged from the germination behaviour of trialSeite - 2 -plants both in laboratory conditions and outdoors, in order to optimise the technical characteristics of the heating textile for use operationally.
