PHYTOTOXICITY OF SALTS IN COMPOSTED SEWAGE SLUDGE AND CORRELATION WITH SODIUM CHLORIDE,CALCIUM NITRATE,AND MAGNESIUM NITRATE |
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| Authors: | Hong Cai Ding Gao |
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| Institution: | 1. Center for Environmental Remediation , Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences , Beijing, China;2. Graduate University of Chinese Academy of Sciences , Beijing, China;3. Center for Environmental Remediation , Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences , Beijing, China |
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| Abstract: | The phytotoxicity of salts in composted sewage sludge (CSS) was evaluated. Concentrations of sodium (Na+), chloride (Cl?1), calcium (Ca2+), and magnesium (Mg2+) were present at levels that would induce salt stress in plants. Nutrient imbalances were also found that would adversely affect the use of CSS as a growth medium. To further understand the phytotoxic nature of these salts, sodium chloride (NaCl), calcium nitrate Ca(NO3)2] and magnesium nitrate Mg(NO3)2] solutions were used to simulate the composition of salts found in CSS in an investigation of radish (Raphanus sativus L.) seed germination. High concentrations of Ca2+ (92.1 mmol.L?1) and Mg2+ (27.4 mmol.L?1) inhibited seed germination to an equal extent as did Na+ (40.6 mmol.L?1). The lower concentration of Ca2+ (10 mmol.L?1), however, significantly relieved the stress caused by NaCl. These results indicated that the composition and total amount of Na+, Cl?1, Ca2+, and Mg2+ in CSS should be carefully monitored before it is used as a soil amendment or growth medium. |
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| Keywords: | sewage sludge compost salt stress nutrient balance phytotoxicity |
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