Effect of irrigation with treated wastewater on soil chemical properties and infiltration rate

In Tunisia, water scarcity is one of the major constraints for agricultural activities. The reuse of treated wastewater (TWW) in agriculture can be a sustainable solution to face water scarcity. The research was conducted for a period of four years in an olive orchard planted on a sandy soil and subjected to irrigation treatments: a) rain-fed conditions (RF), as control b) well water (WW) and c) treated wastewater (TWW). In WW and TWW treatments, an annual amount of 5000 m3 ha-1 of water was supplied to the orchard. Soil samples were collected at the beginning of the study and after four years for each treatment. The main soil properties such as electrical conductivity (EC), pH, soluble cations, chloride (Cl-), sodium adsorption ratio (SAR), organic matter (OM) as well as the infiltration rate were investigated. After four years, either a significant decrease of pH and infiltration rate or a significant increase of OM, SAR and EC were observed in the soil subjected to treated wastewater treatment

Influence of irrigation with moderate saline water on "chemlali" extra virgin olive oil composition and quality

The main goal of this study was to investigate the effects of moderate saline water irrigation in the "Chemlali" olive cultivar grown in Sfax, an arid region of Tunisia, on the composition and quality of the resultant virgin olive oil in comparison to a control plot grown under rain-fed conditions. Free acidity, peroxide value, specific ultraviolet absorbance (K(232), K(270)), fatty acid composition, induction time, total polyphenol and total chlorophyll contents were determined and reported. The irrigation did not affect free acidity and peroxide value. Whereas, specific ultraviolet absorbance (K(232), K(770)), fatty acid composition, induction time, total polyphenol and total chlorophyll contents were affected by irrigation. Rain-fed virgin olive oils showed a statistically significant higher content of oleic and linoleic acids. Virgin olive oils extracted from moderate saline water irrigated trees had higher contents of palmitic, palmitoleic, stearic and linolenic acids and a longer shelf-life. A positive correlation was noted between polyphenol content and oxidative stability

Effects of irrigation with treated wastewater on olive tree growth, yield and leaf mineral elements at short term

In arid regions, such as Tunisia, the reuse of treated wastewater (TWW) in agriculture can be a sustainable solution for water scarcity. A two-year field experiment was conducted in order to investigate the short term effects of TWW on olive growth, yield and concentration of total nitrogen (Nt), potassium (K), phosphorous (P), and heavy metals (i.e. Zn, Mn, Pb and Cd) in olive leaves. Olive trees were subjected to the following irrigation treatments: (i) trees irrigated with well water (WW) and (ii) trees irrigated with treated wastewater (TWW). For both treatments, the TWW and WW were applied at a rate of 4.5m3 day−1 tree−1 (5000m3 ha−1 year−1). After two years, non-significant injuries caused by salts and/or heavy metals were observed on shoot growth of trees irrigated with TWW. The application of TWW significantly increased concentration of Nt, P and K in the leaves, whereas heavy metals (Zn and Mn) showed a significant increase only after the second year of irrigation

Effect of the seasonal climatic variations on the composition and quality of “Chemlali” virgin olive oil

“Chemlali” is the main olive variety cultivated in Tunisia. Seasonal factors such as rainfall and temperature vary year to year influencing the composition and quality of virgin olive oil. This work aims to investigate the effect of the seasonal climatic variations on the quantity and the quality characteristics (free acidity, specific ultraviolet absorbance K232 and K270, fatty acid composition, chlorophylls and total phenols) of Tunisian “Chemlali” olive oil. Water and oil content increased with increasing rainfall and temperature respectively. The seasonal variations of climatic factors within the growing region did not affect the main legal quality indices of all oil samples. K232, total phenol contents and oxidative stability increased at high temperature, while K270 and chlorophyll content decreased

Alternate bearing affects nutritional status and net assimilation rate of an irrigated olive grove under arid conditions

Alternate bearing is a typical behavior of various fruit tree crops and is common among olive cultivars (Olea europæa L. var. sativa Hoffm. e Lk.). Since this phenomenon affects yield and consequently oil production, it is a concern for olive oil industry in order to offer a constant olive oil amount each year. A 4-year field experiment was conducted on cv Chemlali olive trees in ‘on’ and ‘off’ years in order to study, under arid conditions, both annual macro-element balance and net photosynthetic activity. Shoots growth was much higher in the ‘off’ year with respect to the ‘on’ one (+11.70 cm vs. +2.60). Net photosynthesis rate was much higher in the ‘off’ year with respect to the ‘on’ year and the highest values were observed at spring, when there is an intense vegetative growth. Differences for the mineral elements were observed between the ‘on’ and ‘off’ years. Nitrogen accumulated in leaves mainly in spring in the ‘off’ year, whereas high N values were detected also at the end of summer in the ‘on’ year. Consequently, N fertilization can be accomplished in February–March and possibly after harvest (November–December) to be used at budburst in the successive season. A difference was found between leaf P concentrations in ‘on’ or ‘off’ years from flowering to fruit-set, with the lowest values in the ‘on’ year, in particular in June–July. A supply of P at autumn–winter and partially in spring–summer in particular in an ‘on’ year would be appropriate. K accumulated in leaves in ‘on’ year from spring to summer, thus a supply of K in January–February, before new vegetation, for trees either in ‘on’ or ‘off’ year can be necessary for supporting and implementing the root system activity and the successive shoot growth (‘off’ year) and fruit development (‘on’ year). These results should be useful to partially reduce, through an appropriate fertilization schedule, the alternate bearing in olive tree

Short Term Treated Wastewater Reuse Impact on Soil Microbial Biomass, Bacterial Functional Diversity and Enzymatic Activities in the Presence of Earthworms Eisenia Andrei

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