Exploration of Recycling Pathways for Coir Spent Substrate to Establish Recycling for By-Products of Protected Cultivation

In recent years, the expansion of protected cultivation areas has led to substantial increase in by-products, including coir spent substrate.Coir is widely used as an eco-friendly growing medium.However, its recycling after use is limited due to interpretational differences in government regulations, necessitating the rational recycling pathway.Fertilization represents the most cost-effective option.While the Ministry of Environment classified coir spent substrate as "other vegetable remnants (51-17-29)", allowing for fertilization, the Rural Development Administration does not recognize it as a raw material under the Fertilizer Control Act, creating institutional limitations.This study estimated the annual generation of coir spent substrate in tomato cultivation farms and analyzed its inorganic and heavy metal contents.The results showed that coir spent substrate contained abundant inorganic components, including Ca 11.1gkg -1 , K 3.61gkg -1 , Mg 2.02gkg -1 , P 1.31gkg -1 , Mn 0.44gkg -1 , Si 0.188gkg -1 , and B 0.037gkg -1 .The contents of heavy metals including Ni, Cu, Zn, As, Cd, Pb and Hg were all confirmed to be below the allowable limits.Additionally, based on national statistics, the annual generation of coir spent substrate in tomato cultivation farms in korea was estimated at approximately 49,000 tons.These results suggest that the large amount of coir spent substrate generated poses a low environmental risk and contains abundant inorganic components and have high potential as a fertilizer raw material.It could become an effective recycling system for coir spent substrate if the recycling pathway proposed in this study is institutionally supported through consensus among stakeholders.