Almond shell waste: Possible local rockwool substitute in soilless crop culture

This industrial residue is the woody endocarp of the almond fruits. This material is normally incinerated or dumped without control. Almond shell used (100% pure) as growing media can be more ecologically-friendly and less expensive than traditional rockwool since it can be locally produced. Three commercially produced random samples of two different textures and two volumes (19 and 25 L) were evaluated as growing media for soilless production. Three experiments were conducted to evaluate the effects of volume and texture and to compare this substrate with rockwool in terms of yield and quality characteristics of fruits in melon and tomato culture. The physical, physico-chemical and chemical properties studied did not differ significantly between both textures. Tomato plants grown in almond shell residue used 21% less water compared to rockwool over the course of production. We found non-limiting in comparison to rockwool for melon and tomato crops in relation to fertigation parameters, water uptake and yield. Significant differences of yield were found when we used the big size, specially in melon crop where commercial yield and soluble solids of plants growing on 25 L bags was higher than that on small one. The results suggested that almond shells seem to be an acceptable growing media as rockwool substitute for soilless vegetable production.