Effects of olive mill wastewater on soil carbon and nitrogen cycling

• Published in: Applied microbiology and biotechnology 2014-03, Vol.98 (6), p.2739-2749
• Main Authors: Tsiknia, Myrto, Tzanakakis, Vasileios A, Oikonomidis, Dimitris, Paranychianakis, Nikolaos V, Nikolaidis, Nikolaos P
• Format: Article
• Language: English
• Subjects: Ammonia; Ammonium Compounds - analysis; Analysis; application rate; Archaea - enzymology; Archaea - genetics; Bacteria; Bacteria - enzymology; Bacteria - genetics; Biogeochemistry; Biomedical and Life Sciences; Biotechnology; carbon; Carbon - analysis; Denitrification; DNA, Archaeal - analysis; DNA, Bacterial - analysis; Environmental Biotechnology; Enzymes; Food Handling - methods; Food industries wastewaters; Genes; Genetic aspects; Genetics; Hydraulics; Industrial Waste; land application; Life Sciences; Microbial Genetics and Genomics; Microbiology; Microorganisms; Mills; Moisture content; monophenol monooxygenase; Nitrates - analysis; Nitrification; Nitrogen; Nitrogen - analysis; nitrogen content; Nitrogen cycle; Olea; Olea - chemistry; Olives; Organic chemicals; Organic matter; Oxidoreductases - genetics; Phenol; Phenol - analysis; Phenols; Physiological aspects; Purification; Reproduction; Residuals; Respiration; Sewage; Soil (material); Soil - chemistry; Soil organic matter; Soil treatment; Soil water; Soils; Studies; Waste water; Waste Water - chemistry; wastewater; water holding capacity; Water treatment
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-013-5272-4

This study investigated the cycling of C and N following application of olive mill wastewater (OMW) at various rates (0, 42, 84, and 168 m³/ha). OMW stimulated respiration rate throughout the study period, but an increase in soil organic matter was observed only at the highest rate. Soil phenol content decreased rapidly within 2 weeks following application but neither phenol oxidase and peroxidase activity nor laccase gene copies could explain this response. Soil NH₄ ⁺-N content increased in response to OMW application rate, while an opposite trend observed for NO₃ ⁻-N, which attributed to immobilization. This decrease was in accordance with amoA gene copies of archaeal and bacterial ammonia oxidizers in the first days following OMW application. Afterwards, although amoA gene copies and potential nitrification rates recovered to values similar to or higher than those in the non-treated soils, NO₃ ⁻-N content did not change among the treatments. A corresponding increase in denitrifying gene copies (nirK, nirS, nosZ) during that period indicates that denitrification, stimulated by OMW application rate, was responsible for this effect; a hypothesis consistent with the decrease in total Kjeldahl nitrogen content late in the season. The findings suggest that land application of OMW is a promising practice for OMW management, even at rates approaching the soil water holding capacity.