Agriculture Reference
In-Depth Information
14.2 METHOD
14.2.1 STUDY AREA
The study area consists of 100 ha of new greenhouses that were construct-
ed during 2008-2009 on land that had previously been cultivated for 3126
decades under a non-intensive growing regime (mostly rain-fed open field
crops). The site is located on the Mediterranean coastal plain, south of the
city of Ashkelon, Israel (3123-6 km from the sea shoreline). Most of the
greenhouses in this area produce high-quality vegetables year round through
organic methods (80 %), while the rest practice conventional methods.
Underneath these agricultural fi elds (31215-30m below the surface)
lies a phreatic sandy aquifer that is characterized by high water quality
(Cl
−
<200 mg L
−1
; NO
3
−
<40 mg L
−1
). This part of the aquifer is an impor-
tant water source for the region. Its water is used for domestic and agri-
cultural purposes through a large number of pumping wells. In addition,
the aquifer in the region serves as an underground storage area through the
artifi cial infi ltration of fl ood water from the Shikma ephemeral stream and
the water surplus from the national water carrier.
The climate in the area is Mediterranean with an annual average precipita-
tion of 458mm (Israeli Water Authority, 2013). The majority of the rain events
take place during the winter, between December and February. The annual
average temperature is 20.2 C. The coldest month is January with average
maximum and minimum temperatures of 17.2 C and 8.1 C, respectively. The
warmest month is August with average maximum and minimum temperatures
of 31.1 and 21.4 C, respectively (Israel Meteorological Service, 2013). The
pan evaporation rate changes from an average of 2.2mm per day in January
to 7.5mm per day in July (Israel Meteorological Service, 2013). Note that
the studied sites are all located inside large greenhouses (3121 ha each) that
are not infl uenced by the rain pattern, and their interior climate is warmer
and more humid than external natural conditions. Most of the cultivated areas
are located in large interdune valleys, surrounded by sandy dunes with sparse
vegetation. The stratigraphic cross section of both sites is characterized by in-
terchanges of sandy clay loam to clay loam layers. Yet the vadose zone under
the organic farm includes more presence of clay loam layers.
