Campbell Scientific Sentek TriSCAN® Manual v 1.2a User Manual
Page 54
TriSCAN Manual Version 1.2a
Copyright © 1991 – 2004 Sentek Pty Ltd All rights reserved
Page 47
Table 12. Crop Tolerance and Yield Potential of Fruit Crops as Influenced by Irrigation Water Salinity (EC
w
)
and Soil Salinity (EC
e
) – from Ayars and Westcott 1994
Adapted from Maas and Hoffman (1977) and Maas (1984). These data should only serve as a guide to
relative tolerances among crops. Absolute tolerances vary depending upon climate, soil conditions and
cultural practices. In gypsiferous soils, plants will tolerate about 2 dSm
-1
higher soil salinity (EC
e
) than
indicated but the water salinity (EC
w
) will remain the same as shown in this table.
EC
e
means the average root zone salinity as measured by electrical conductivity of the saturation extract of
the soil, reported in deciSiemens per meter (dSm
-1
) at 25°C. EC
w
means electrical conductivity of the
irrigation water in deciSiemens per meter (dSm
-1
). The relationship between soil salinity and water salinity
(ECe = 1.5ECw) assumes a 15-20 percent leaching fraction and a 40-30-20-10 percent water use pattern for
the upper to lower quarters of the root zone.
The zero yield potential or maximum EC
e
indicates the theoretical soil salinity at which crop growth ceases.
Tolerance evaluation is based on tree growth and not on yield.
Yield Potential
100 %
90 %
75 %
50 %
0 %
(maximum)
Fruit crops
EC
e
EC
w
EC
e
EC
w
EC
e
EC
w
EC
e
EC
w
EC
e
EC
w
Date palm
(Phoenix dactylifera)
4.0
2.7
6.8
4.5
11.0
7.3
18.0
12.0
32.0
21.0
Grapefruit
(Citrus paradisi)
1.8
1.2
2.4
1.6
3.4
2.2
4.9
3.3
8.0
5.4
Orange
(Citrus sinensis)
1.7
1.1
2.3
1.6
3.3
2.2
4.8
3.2
8.0
5.3
Peach
(Prunus persica)
1.7
1.1
2.2
1.5
2.9
1.9
4.1
2.7
6.5
4.3
Apricot
(Prunus armeniaca)
1.6
1.1
2.0
1.3
2.6
1.8
3.7
2.5
5.8
3.8
Grape
(Vitis sp.)
1.5
1.0
2.5
1.7
4.1
2.7
6.7
4.5
12.0
7.9
Almond
(Prunus dulcis)
1.5
1.0
2.0
1.4
2.8
1.9
4.1
2.8
6.8
4.5
Plum, prune
(Prunus domestica)
1.5
1.0
2.1
1.4
2.9
1.9
4.3
2.9
7.1
4.7
Blackberry
(Rubus sp.)
1.5
1.0
2.0
1.3
2.6
1.8
3.8
2.5
6.0
4.0
Boysenberry
(Rubus ursinus)
1.5
1.0
2.0
1.3
2.6
1.8
3.8
2.5
6.0
4.0
Strawberry
(Fragaria sp.)
1.0
0.7
1.3
0.9
1.8
1.2
2.5
1.7
4.0
2.7