A study of olive mill wastewaters obtained from different treatment processes effects on chemical and microbial properties of a Typic Xerofluvent soil and wheat yield

Abstract

This study was carried out to investigate the potential for the usability of treated olive mill wastewater (OMW) as an organic amendment in agricultural soils under Mediterranean climate conditions. OMW was treated by two different treatment processes as economical (E-OMW) and advanced (A-OMW). The treated OMWs and raw OMW (R-OMW) were applied to a loamy soil at a rate of 100 m 3 ha-1 year-1 for 2 years. Soils were sampled 15 days and about 5 months (at harvest) after OMW application for chemical and microbial analyses in each year. The total concentrations of N, P, Cu, Zn, and phenol of R-OMW decreased after both treatment processes while salinity (EC) and the total amounts of K, Na, and Ca increased. The applications of OMW caused changes in soil chemical (pH, EC, P ext , K ext) and microbial (microbial biomass-C (MB-C), microbial biomass-N (MB-N), basal soil respiration (BSR), N-mineralization (N-min)) characteristics (P < 0.05). In the second year of the experiment, initial samplings showed that the values of soil pH and EC increased significantly under all OMW applications compared to the control. High P ext concentrations were determined in soils amended with R-OMW, while there were high K ext concentrations in soils amended with the treated OMWs. The increases determined in MB-C and MB-N at all sampling times resulted in high MB-C/TOC and MB-N/TN ratios in soils amended with the treated OMWs. The wheat grain yield over the 2-year period showed that the application of the treated OMWs had a positive effect. It was determined that no negative effects occurred for either soil properties or wheat growth with the treated OMW applied at rates of up to 100 m 3 ha-1. The addition of treated OMW after removal of its phenolic components may be considered as a good option for evaluating this waste in countries where OMW causes serious environmental pollution.

Olive Mill Wastes: A Source of Bioactive Molecules for Plant Growth and Protection against Pathogens

“…In particular, aerobic bacteria and fungi increase in proportion with OMW spreading rates. Furthermore, soil respiration [96,99] and soil enzyme activities (dehydrogenase, β-glucosidase, and urease) seem to be enhanced in OMW-amended soils [122,123].…”

“…The long term application of OMW in general did not cause significant differences in pH, EC, P, Na. However, pH, EC, and salinity can increase temporarily in topsoil after spreading high rates (200 m 3 /(ha*year)) of OMWW [103][104][105][121][122][123]. -Physical and hydrological properties: Different results are reported in the function of forms of OMW (solid or liquid), rates of application, and pretreatments.…”

The determination of grain yield, yield components, and macro nutrient content of corn (Zea Mays L.) by different agricultural practices

“…These wastes (Nicotiana tabacum) are phytotoxic due to their high content of alkaloids which if not well-managed can cause environmental damage (Adediran et al, 2003;Mumba and Phiri, 2008). Composting of these wastes can reduce the alkaloid content and convert them into useful materials (Adediran et al, 2004;Okur et al, 2008;Cercioglu et al, 2012;Nguyen et al, 2022). Organic wastes such as manures, composts and plant residuals are frequently used in crop production systems as an alternative to mineral fertilizers, to restore degraded soils and ameliorate physicochemical constraint (Celestina et al, 2019).…”