Management of Salt-Affected Soils - Practices of Irrigation and On-farm Water Management - page 301

Example 8.2

Estimate the actual yield of a rice variety which is grown in a field having EC of
soil saturate (EC e ) = 10 dS/m, critical salinity level above which the yield reduction

starts (EC t ) = 6 dS/m, the salinity level at which yield becomes zero = 20 dS/m,

and potential yield in a nonsaline situation = 5.0 t/ha.

Solution

EC 0 − EC e

We know, relative yield, Y r = 100 ×

EC 0 − EC 100

Here, EC e = 10 dS/m

EC 0 = 20 dS/m

EC 100 = 6 dS/m

Thus, Y r =

20 − 10

100 ×

6 =

71.42% = 0.7142

20 −

Y act = Y r × Y p = 0.7142 × 5 = 3.57 t/ha (Ans.)

8.6 Management/Amelioration of Saline Soil

The mechanisms of formation of saline soils are important but what is even more
important is the management of the infected soil and how to slow the formation of
salinity in these soils. Remediation of salt contaminated sites and managing high
salt content soil for crop production are more effective if the specific nature of the
salt in the soil is considered.

8.6.1 Principles and Approaches of Salinity Management

Strategies for management of saline soil lie mainly on the following principles:

1. Reduction of capillary rise of saline underground water
2. Increasing downward movement of fresh water (mainly rainwater) for washout
of salts
3. Controlling saline water intrusion
4. Escape of high salinity period by proper crop calendar/crop adaptation
5. Introduce crop cultivars adaptable to developed salinity level

Salt-affected soils exist under a wide range of hydro-geological, physiographical
conditions, soil types, rainfall and irrigation regimes, and different socioeco-
nomic conditions. Therefore, a single technique or system may not be applicable
to all areas and conditions. Several practices may be required to combine into
an integrated system that functions satisfactorily under the prevailing produc-
tion constraints and soil types to give together economic benefit on a sustainable
basis.