Irrigation of grapevines using treated wastewater: effects on fruit composition and plant nutrient status–first results

Abstract

The aim of this paper is to present preliminary results (two seasons 2013-2014) forming part of a long term investigation on the effects of using treated wastewater for irrigation of grapevines Vitis vinifera cv. Viognier B and Carignan N. The experimental plots are established on limestone and sandy loam soils and grown under Mediterranean conditions of southern France. Four types of water were used: drinking water (control), treated wastewater quality B* and C*, and agricultural water. All vines received 2.5 L/plant/irrigation through a drip irrigation system.

The level of water deficit was determined using a model for vine irrigation management for white and red grapes, based on weekly pre-dawn water potential measurements (Ψpd). Results showed that the nutrient concentrations in leaf petioles –at the stage of fruit set in 2014 were not affected by the irrigation treatments (p≤0.05), supplied during the 2013 growing season when the experiment started. Berry weight, concentration of soluble solids (sugar), titratable acidity, pH and assimilable nitrogen at harvest were similar, regardless of the type of water used for irrigation. The vines receiving treated wastewater showed the highest nitrogen level in grapes during the 2014 growing season, although not significant (p≤0.05). In both seasons, fruit composition and plant nutrient status were more sensitive to the year characteristics (climate variation) than the supplied water quality. At this stage of the experimentation, the different qualities of water used for grapevine irrigation had no significant effect on plant water status, on berry composition and leaf petioles nutrient status. This study serves as a baseline for continuing research in the field of wastewater reuse. Ongoing and future research will include a complete analytical program in order to establish the effect of treated wastewater on soil, groundwater, plant, fruit and wine profiles.

* Level of sanitary quality of treated wastewater according to parameters from the French decree of 25 June 2014 (NOR: AFSP1410752A).