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4449685 
Journal Article 
Seaweed compost for agricultural crop production 
Cole, AJ; Roberts, DA; Garside, AL; de Nys, R; Paul, NA 
2016 
Yes 
Journal of Applied Phycology
ISSN: 0921-8971
EISSN: 1573-5176 
28 
1 
629-642 
WOS:000369243300063 
This study manipulated the carbon-to-nitrogen ratio (C:N) of seaweed composts by varying the proportion of high N green seaweed (Ulva ohnoi) and high C sugarcane bagasse to assess their quality and suitability for use in agricultural crop production. Seaweed-bagasse mixes that had an initial C:N ratio greater than 18:1 (up to 50:1) could be transformed into a mature compost within 16 weeks. However, only composts with a high seaweed content and therefore low initial C:N (18 and 22:1) supported a consistently high rate of plant growth, even at low application rates. Sugarcane grown in these high seaweed composts had a 7-fold higher total above-ground biomass than low seaweed composts and a 4-fold higher total above-ground biomass than sugarcane grown in commercial compost that did not contain seaweed. Overall, the optimal initial C:N ratio for seaweed-based compost was 22:1 which corresponds to 82 % seaweed on a fresh weight basis. This ratio will produce a high quality mature compost whilst also ensuring that a high proportion of the nitrogen (> 90 %) in the Ulva biomass is retained through the composting process. 
Macroalgae; Phosphorous; Nitrogen; Agriculture; Salt; Electrical conductivity