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Fate of Soil‐Applied Olive Mill Wastewater and Potential Phytotoxicity Assessed by Two Bioassay Methods
Author(s) -
Saadi Ibrahim,
Raviv Michael,
Berkovich Shimrit,
Hanan Aviva,
Aviani Ido,
Laor Yael
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0331
Subject(s) - phytotoxicity , bioassay , loam , lepidium sativum , environmental science , soil water , agronomy , water content , wastewater , chemistry , ecotoxicity , environmental chemistry , environmental engineering , soil science , germination , biology , ecology , toxicity , geotechnical engineering , organic chemistry , engineering
Controlled land spreading of untreated olive mill wastewater (OMW) has been widely practiced as a means of its disposal. However, potential phytotoxic effects are critical for the selection of sites and crop types and for proper synchronization between land application and cropping. This study traced the fate of dissolved organic carbon (DOC), total phenols (TP), electrical conductivity, pH, microbial counts, and phytotoxicity to cress ( Lepidium sativum L.) after soil application at doses equivalent to 80, 160, and 320 m 3 ha −1 . Vertisol (fine‐clayey) and Loess (sandy loam) soils were treated and incubated at 12 or 25°C and at moisture contents maintained at 70% of field water capacity or gradually reduced from 70 to 20% without compensation. Temperature, rather than moisture content, had a major effect on removal rates of DOC and TP. The maximum combined effect of warm temperature and higher moisture content resulted in removal rates greater than those under cooler, drier conditions by factors of up to 1.8 and 4.1 for DOC and TP, respectively. Favorable biodegradation conditions were indicated by increased numbers of total soil microorganisms and fungi by factors of up to 26 and 5, respectively. A whole‐soil bioassay was developed to assess the dynamics of residual soil phytotoxicity after OMW application. Phytotoxicity measurement in soil extract generally showed stronger inhibition or stimulation activity than measurement in whole soil, depending on soil type and OMW dose. The newly developed bioassay seems to be useful for the refinement of general recommendations regarding permitted OMW application doses.