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 selectionof sites and crop types and for proper synchronization between landapplication and cropping. This study traced the fate of dissolvedorganic carbon (DOC), total phenols (TP), electrical conductivity,pH, microbial counts, and phytotoxicity to cress (Lepidium sativumL.) after soil application at doses equivalent to 80, 160, and 320m3 ha-1. Vertisol (fine-clayey) and Loess (sandy loam) soils weretreated and incubated at 12 or 25°C and at moisture contentsmaintained at 70% of field water capacity or gradually reducedfrom 70 to 20% without compensation. Temperature, rather thanmoisture content, had a major effect on removal rates of DOCand TP. The maximum combined effect of warm temperature andhigher moisture content resulted in removal rates greater than thoseunder cooler, drier conditions by factors of up to 1.8 and 4.1 forDOC and TP, respectively. Favorable biodegradation conditionswere indicated by increased numbers of total soil microorganismsand fungi by factors of up to 26 and 5, respectively. A whole-soilbioassay was developed to assess the dynamics of residual soilphytotoxicity after OMW application. Phytotoxicity measurementin soil extract generally showed stronger inhibition or stimulationactivity than measurement in whole soil, depending on soil type andOMW dose. The newly developed bioassay seems to be useful forthe refinement of general recommendations regarding permittedOMW application doses. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
See also:
Laor, Y., Saadi, I., Raviv, M., Berkovich, Sh., Hanan, A., Aviani, I.. (2012). Fate of soil-applied olive mill wastewater and potential phytotoxicity assessed by two bioassay methods. pp. 17-21 in: Proceedings of the 8th International ORBIT 2012 Conference, Rennes, France, June 12-15, 2012.
