ISHS Acta Horticulturae 633: XXVI International Horticultural Congress: Protected Cultivation 2002: In Search of Structures, Systems and Plant Materials for Sustainable Greenhouse Production
CONSEQUENCES OF CLOSED SOILLESS GROWING SYSTEMS FOR THE RECIRCULATING NUTRIENT SOLUTION AND THE PRODUCTION TECHNIQUES |
| Authors: | F. Benoit, N. Ceustermans |
| Abstract:
In 1973 NFT changed from a scientific working instrument into a revolutionary production system. The exponential increase in the large-scale applications of soilless culture found its driving force in the economic advantages of it and more precisely in yield increases of at least 25%. A first major problem concerns the quality of the available water. In northern areas the disadvantages of groundwater (Fe, NaCl, HCO3, B) have been sidestepped by means of rainwater basins, whereas in southern areas, which do sometimes have abundant precipitation, these basins have hardly found any application yet. The closed NFT system may be regarded as the precursor of the good ecological agrarian practice (GAP) that is emphasized so strongly today. However, this technique is being applied only on a limited scale for leaf crops and herbs. Within the substrate culture the recirculation of drain water changed from a compelling guideline into a generally accepted ecological and economic option. Partly also due to the accumulating disposal heap caused by the rockwool substrate in the eighties, more and more longer-lasting inert (PUR, Perlite) and organic (wood fibres, coir) substrates were introduced. The characterisation of their physical and chemical properties resulted in far-reaching improvement of the control of the nutrient composition and of the trickling regime. Within the NFT system, mechanization developed strongly since the beginning of the eighties in the form of the “Floating Plant System”, the “Mobile Gully Lid System” and the “Mobile Gully System”. Within the framework of the integrated ecological production system the physical disinfection techniques close the circle. Meanwhile the possibilities and the limitations of methods such as Slow Sand Filtration, Low Pressure UVc and others are being intensely examined today. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
