The parameters for calculating the effect of salinity stress on crop yield are entered in the Salinity Stress tab of the Crop input screen.  This tab is enabled if the project type is Salinity.

 

Crop yield response to salinity is traditionally described for a given crop by plotting two linear lines, one a tolerance plateau at a relative yield of 100% up to a salinity threshold, and the other a concentration dependent line whose slope indicates the yiled reduction per unit increase in the soil salinity (Maas and Hoffman, 1979). For sopil salinity exceeding the threshold of any given crop, relative yield (YRs) can be estimated with the following equation:

 

YRs = 100 - B*(SAL - A)

 

where A is the salinity threshold expressed in mg/l; B is the slope expressed in % per mg/l; and SAL is the mean salinity of the saturated soil extract in the root zone.  The coefficients A & B for  69 crops were given by Maas and Hoffman (1977).  Some of the values for fiber, grain and special crops are given in the table below.  Most of the data were obtained from crops grown under conditions that simulated recommended cultural and management practices for commercial production.  The data apply only where the crops are exposed to fairly uniform salinities from the late seedling stage to maturity.

 

Table 16.  Salt tolerance and salinity parameters for selected crops (Maas and Hoffman, 1977).

 

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                 Threshold                      Slope

 

Crop                           dS/m                        (% per dS/m)

 

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Barley                    8.0                              5.0

Bean                            1.0                             19.0

Broad bean                    1.6                              9.6

Corn                            1.7                             12.0

Cotton                    7.7                              5.2

Flax                            1.7                             12.0

Peanut                    3.2                             29.0

Rice, paddy                    3.0                             12.0

Sorghum                    6.8                             16.0

Soybean                    5.0                             20.0

Sugar beet                    7.0                              5.9

Sugarcane                    1.7                              5.9

Wheat                            6.0                              7.1

 

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