Abstract
Volume expansion ratio (VE) and water retention capacity (WRC) are the most important quality parameters for compressed coir pith products and specifically for coco discs used as potting medium. The effects of time duration of retting, method of retting and drying techniques on the quality of coir pith and coco discs were examined. Quality variations in coir fibre with the time duration of retting were also analysed. VE and WRC of coco discs were found to increase significantly, while the pH changed marginally and electrical conductivity (EC) dropped significantly with the increase of retting time. VE, WRC, pH and EC after 12 weeks of retting were found to be 5.77 ± 0.19, 5.87 ± 0.35, 5.99 ± 0.04 and 63 ± 8 μs/cm, respectively. Length, tensile strength and breaking load of coir fibre were found to improve from 133 ± 1 to 182 ± 9 mm, 81 ± 7 to 104 ± 12 N/mm2 and 3.58 ± 0.42 to 4.32 ± 0.38 N, respectively within 4 to 12 weeks of retting. Time duration for retting could be reduced to less than 4 weeks to achieve similar properties in coir fibre and coir pith by crushing the husks before retting. Oven drying resulted in rupturing of the cells and case hardening of coir pith. Hot air drying was found to be the most effective method for drying coir pith as compared to sun drying and oven drying