Rockwool in horticulture, and its importance and sustainable use in New Zealand

A brief history of the beginnings of the use of rockwool in horticulture in overseas countries, an outline of uses overseas of the current forms of water absorbent and water repellent horticultural rockwool, a summary of manufacturers of the product, a consideration of some of its advantages and disadvantages, and a listing of the crops grown in horticultural rockwool are given in this paper. An outline of the overseas experiences in both the disposal of and the sustainable reuse of horticultural rockwool is also given. A history of use in New Zealand of horticultural rockwool and the crops grown on the product are outlined. Options, which are both within and outside horticulture, for the sustainable reuse of the relatively small volume (c. 300 m(3)/year) which becomes available for reuse in New Zealand at present are described and discussed. Many of these options may be applicable in other countries where the volume of horticultural rockwool used is relatively small.