Abstract
Reuse of treated wastewater (TWW) for irrigation is one of the solutions
to water shortage. Not only it saves water, it also supplies organic
matter (OM) and other nutrients to the soil. However, long term
application of TWW can affect soil physical and chemical properties.
Additionally, substances added via TWW irrigation can accentuate already
existent soil heterogeneity, which may impact physical and chemical
processes in soils. As more agricultural fields are being irrigated with
TWW, it is crucial to understand its implications on soils. The
objectives of this research are to investigate: (a) the impact of TWW
irrigation on soil heterogeneity, and on hydraulic processes; and (b)
the fate of salts and nutrients in the subsurface in soils irrigated
with TWW vs. tap water (TP). The experiment is carried out in Lachish
farm, Israel. Two trenches were dug and a sensors network of 38
tensiometers, 37 TDRs, 6 redox probes, and 38 thermocouples was
installed in high resolution in each cross section (1.5 x 1.5 m). The
cross sections are 13 meters apart in a vineyard irrigated for over 10
years with TP and TWW. One cross section is in a TP area while the other
is in TWW area. Soil samples were collected according to visually
observed heterogeneity of the soil profiles and randomly. Chemical
analyses were conducted in both soil and water samples. In addition,
infiltration rate, Leaf Area Index (LAI), and harvest yield were
determined. For irrigation water analyses, DOM in TWW is higher than TP
(average concentrations of 25.9 and 1.4 mg/L, respectively). Soil
organic matter is in average 1% higher in soils irrigated with TWW in
the first 10 cm, while for lower depths OM content is the same under
both treatments. No repellency was detected for either soils (WDPT<
5s), probably due to high clay content (>40%). ESP, EC and pH were
higher for TWW soils, but not high enough to be characterized as saline
and/or sodic. However, it presented SAR and EC levels of moderate
infiltration reduction risk. Infiltration rate was lower in soils
irrigated with TWW in respect to TP (1.05 and 5.46 cm/h, respectively).
In addition, harvest yield was significantly higher in crop irrigated
with TWW than TP (10.7 and 7.0 kg grapes/tree, respectively). Soil
temperature was higher for TP profile, under same plant canopies (LAI =
2.1). For irrigated, dry and rainy seasons WC was higher in the TWW
plot, reaching differences of up to 10% and higher retention capacity.
In addition, WC varied considerably within the same depth in the TWW,
reaching differences of up to 7% in the dry period, while TP station
differences were up to 2%, which indicates increase in spatial
heterogeneity. Overall, there were changes on physical characteristics
of soils irrigated with TWW (higher retention capacity, lower
temperature, lower infiltration rates) which had an impact on other
processes. The research is still on-going, and the responsible
mechanisms for the observed phenomena are still under exploration.
Original language | English |
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Title of host publication | American Geophysical Union, Fall Meeting 2013 |
State | Published - 1 Dec 2013 |
Event | American Geophysical Union, Fall Meeting 2013 - San Francisco, United States Duration: 9 Dec 2013 → 13 Dec 2013 http://fallmeeting.agu.org/2013/ |
Conference
Conference | American Geophysical Union, Fall Meeting 2013 |
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Country/Territory | United States |
City | San Francisco |
Period | 9/12/13 → 13/12/13 |
Internet address |
Keywords
- 1875 HYDROLOGY Vadose zone
- 1895 HYDROLOGY Instruments and techniques: monitoring
- 1842 HYDROLOGY Irrigation
- 1865 HYDROLOGY Soils