Evaluation of Mussel Sediments Fertility Value.

Large quantities of mussel sediments are generated as a waste from washing mussels each year in Atlantic Canada, with no readily available recycling outlet. With rising disposal costs and a shift toward sustainable management, alternative methods of handling these wastes must be investigated. In this study mussel sediments were (i) tested for nutrient concentration and consistency during the year, and (ii) evaluated as a soil amendment to improve crop growth. Duplicate mussel sediment samples were collected bi-weekly and were analyzed for total nutrient concentration. Tomato and annual ryegrass were grown as test plants in a completely randomized design with four replications for 90 days under greenhouse conditions. Treatments included control, three rates of mussel sediments [14,000 (S14), 28,000 (S28), 42,000 (S42) L ha^-1 wet weight basis], and NPK fertilizers (NH₄NO₃, triple super phosphate and KCl) based on soil test recommendations (F). Sediments’ average dry matter, pH and EC were 17%±4, 7±0.2, 21±21 dS m^-1, respectively. The major nutrients supplied by mussel sediments were N (1.29%±0.20), Ca (11%±3), Mg (0.64%±0.17), S (0.58%±0.11), B (53ppm±12). Nutrient levels (June 2010 – March 2011) were more consistent for N, Ca, Zn, B and P compared with others. The sediment treatments resulted in 5.5 and 1.9 times (p ≤ 0.001) greater biomass production for tomatoes and annual ryegrass compared with the control, respectively. Total dry biomass produced in S42 was 48% and 44% of F for tomatoes and annual ryegrass, respectively. The increase in biomass was attributed to increase in N supply. The bioavailability of total N in sediments ranged from 23 to 30% and 34 to 41% for tomatoes and annual ryegrass, respectively. The efficiency of mussel sediments N was 31% and 40% of the N fertilizer for tomato and ryegrass, respectively. There was no negative impact of mussel sediment application observed in this study.