Soil salinity related to physical soil characteristics and irrigation management in four Mediterranean irrigation districts

• Published in: Agricultural water management Vol. 98; no. 6; pp. 959 - 966
• Main Authors: Aragüés, R., Urdanoz, V., Çetin, M., Kirda, C., Daghari, H., Ltifi, W., Lahlou, M., Douaik, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2011; Elsevier
• Series: Agricultural Water Management
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; Biological and medical sciences; Calibration; drainage; Drainage control; Drainage measurement; drainage water; Drainage water salinity; Electromagnetic induction (EMI); Electromagnetic induction (EMI) Mediterranean agriculture Irrigation management Irrigation water salinity Drainage water salinity Salt load; equations; evapotranspiration; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; irrigated farming; Irrigation; Irrigation management; irrigation water; Irrigation water salinity; Management; Mathematical analysis; Mediterranean agriculture; Salinity; Salt load; semiarid zones; Soil (material); soil salinity; soil texture; soil water content; surveys; Texture; water salinity; ASE, Morocco; MED, Tunisia; MED, Turkey; Spain; Irrigation management; Irrigation water salinity; Salt load; Electromagnetic induction (EMI); Mediterranean agriculture; Drainage water salinity; Irrigation; Electromagnetic induction; Property of soil; Environmental factor; Irrigation water; Physical properties; Salinity; Salt; Soils; Irrigation schemes; Water engineering; Agriculture; Mediterranean region; Drainage water
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2011.01.004

▶ EMI surveys and the EC
a–EC
e calibration equations satisfactorily appraised irrigation–district soil salinity. ▶ The calibration equations were site-specific, and must be developed for the particular soils of interest. ▶ The EC
a profiles were generally normal or uniform, showing that the soils were subject to salt leaching. ▶ Soil salinity, preponderantly affected by irrigation water salinity and irrigation efficiency, was low to moderate in the four irrigation districts. ▶ Drainage water salinity varied between 9.0 and 1.4
dS
m
−1 and was related to soil salinity and irrigation efficiency. ▶ The control of off-site salt loads requires the reduction of actual high drainage volumes in two of the studied districts.
Irrigated agriculture is threatened by soil salinity in numerous arid and semiarid areas of the Mediterranean basin. The objective of this work was to quantify soil salinity through electromagnetic induction (EMI) techniques and relate it to the physical characteristics and irrigation management of four Mediterranean irrigation districts located in Morocco, Spain, Tunisia and Turkey. The volume and salinity of the main water inputs (irrigation and precipitation) and outputs (crop evapotranspiration and drainage) were measured or estimated in each district. Soil salinity (EC
e) maps were obtained through electromagnetic induction surveys (EC
a readings) and district-specific EC
a–EC
e calibrations. Gravimetric soil water content (WC) and soil saturation percentage (SP) were also measured in the soil calibration samples. The EC
a–EC
e calibration equations were highly significant (
P
<
0.001) in all districts. EC
a was not significantly correlated (
P
>
0.1) with WC, and was only significantly correlated (
P
<
0.1) with soil texture (estimated by SP) in Spain. Hence, EC
a mainly depended upon EC
e, so that the maps developed could be used effectively to assess soil salinity and its spatial variability. The surface-weighted average EC
e values were low to moderate, and ranked the districts in the order: Tunisia (3.4
dS
m
−1)
>
Morocco (2.2
dS
m
−1)
>
Spain (1.4
dS
m
−1)
>
Turkey (0.45
dS
m
−1). Soil salinity was mainly affected by irrigation water salinity and irrigation efficiency. Drainage water salinity at the exit of each district was mostly affected by soil salinity and irrigation efficiency, with values very high in Tunisia (9.0
dS
m
−1), high in Spain (4.6
dS
m
−1), moderate in Morocco (estimated at 2.6
dS
m
−1), and low in Turkey (1.4
dS
m
−1). Salt loads in drainage waters, calculated from their salinity (EC
dw) and volume (
Q), were highest in Tunisia (very high
Q and very high EC
dw), intermediate in Turkey (extremely high
Q and low EC
dw) and lowest in Spain (very low
Q and high EC
dw) (there were no
Q data for Morocco). Reduction of these high drainage volumes through sound irrigation management would be the most efficient way to control the off-site salt-pollution caused by these Mediterranean irrigation districts.