In commercial horticultural crop production, the move away from soil in the 1970s to peat-based systems was stimulated by the need to control problems with soil pests, diseases and nutritional imbalances.
In peat systems, practical problems with water content, water availability and nutrient balance limited its application to certain crops, such as tomatoes. All peat systems require a constant supply of nutrients, either in the form of a slow-release fertiliser or as liquid feeds. Depending on the composition of the background water, nutrient imbalances may quickly occur.
Practical experiences on Jersey with the use of peat bags for the production of spray carnations and pinks highlighted problems with variable moisture availability and also susceptibility to diseases, such as Fusarium species.
Research completed at the States of Jersey Department of Agriculture and Fisheries, Howard Davis Farm glasshouse unit, identified several alternative substrates, such as pumice, clinoptilolite zeolite, nutrient-loaded zeolite, perlite, polyurethane foam and products made from forestry residues.
Most of the active research on hydroponic systems took place over the period 1989 until 1998.
The introduction of rockwool (stonewool) in the early 1970s revolutionised the crop production industry worldwide. Rockwool has been successfully used for long-season production of roses for cut flowers, both in Holland and Guernsey.
Coir is a useful peat replacement material and its popularity as a substrate in UK glasshouse crop production is now increasing.
Using column stocks as an example, control of Fusarium species in the soil has become increasingly difficult over the last ten years, resulting in reduced yields and variable flower quality. In the absence of suitable chemical controls, the reliance on sheet steaming has increased in recent years. However, due to high energy and labour costs, coupled with variable results and negative impacts on soil structural and biological parameters, growers would now like to move away from steaming.
Therefore, following continued problems with disease control in soil-grown crops, there is renewed interest in hydroponics and this has resulted in small-scale trials using coir.
In summary, it is proposed to concentrate on the suitability of the following substrate systems for future hydroponic flower production systems: coir (cocopeat), forestry residues, pumice and rockwool (stonewool).