Abstract
Soluble salts are enriched in sewage sludge compost because of their inherent derivation. Accordingly, the content of soluble salt in sludge compost is usually much higher than most seedlings can tolerate. To determine whether sludge compost is suitable for use as a nursery substrate, some experiments were conducted. Reduction of the electrical conductivity (EC) value could improve seed germination in saturated extract from sludge compost. In addition, water elution and mixing dilution with raw soil were all shown to be able to alleviate saline inhibition on seed germination and seedling growth, including stem diameter, seedling height, and above-ground weight. Overall, salinity is a crucial problem when sewage sludge compost is reused as a nursery substrate, and some effective and convenient approaches to reduce salt should be served prior to its reuse.
Implications:
Sewage sludge after being composted is usually reused as organic fertilizer or plant substrate. However, salt is the main problem during its reclamation. What is the highest salt level the seedling can tolerate? Which types of salts are effective in salinity of sludge-amended substrate? Meanwhile, can the salinity be reduced through water elution or soil mixing dilution? This paper is the first to investigate the salinity and its reduction of sewage sludge compost prior to its use in the development of nursery substrate.
Funding
This study was financially supported by Beijing Nova Program (Z121109002512061), Exploratory Forefront Project for the Strategic Science Plan in IGSNRR, CAS (2012QY005), National High-Tech Research and Development Program of China (2009AA064702), and Agricultural Science & Technology Achievement Transformation Fund Project of China (2012GB24910651).
Additional information
Notes on contributors
Hong-tao Liu
Hong-tao Liu, Guo-di Zheng, and Ding Gao are assistant professors, Tong-bin Chen is a professor and Hong Cai is a Ph.D. candidate in Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
Ding Gao
Hong-tao Liu, Guo-di Zheng, and Ding Gao are assistant professors, Tong-bin Chen is a professor and Hong Cai is a Ph.D. candidate in Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
Guo-di Zheng
Hong-tao Liu, Guo-di Zheng, and Ding Gao are assistant professors, Tong-bin Chen is a professor and Hong Cai is a Ph.D. candidate in Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.