Abstract
The soil salinization in Indus Basin of Pakistan is becoming an important ecological unit among current issues. The use of poor
quality groundwater for irrigation has aggravated the main problem of secondary salinization of the soil. Ground water due to
the presence of salts can be a source of root zone salinization through capillary pressure–induced upward water flow or through
its direct application for irrigation. To identify the more hazardous condition which results in root zone salt concentrations, we
have used a combination of the mass balance equations for water and salt transport, accounting with rainfall distribution,
irrigation application and groundwater contribution. In this study, a stochastic modeling frame work has been developed to
evaluate the behavior of sugarcane cropping system on soil salinity with different irrigation scenarios and watertable
conditions. The simulations were performed for a period of 34-years using actual climatic data for sugarcane crop. The results
indicated that using PDF (Probability Density Functions) drawn value of groundwater salinity in simulations (i.e 0.009 molc.L
-
1
), the mixing of canal water (having salinity value of 0.003 molc.L
-1
) with saline groundwater in any ratio i.e. 0.003 molc.L
-
1
,0.0048 molc.L
-1
,0.006 molc.L
-1
,0.0072 molc.L
-1 and0.009 molc.L
-1
for S1, S2, S3, S4 and S5 scenarios respectively, did not cause
severe salinity problems under 300 cm, 600 cm and 1150 cm deep watertable conditions and long-term rootzone salt
concentration remained below the crop threshold limit (i.e. 0.017 molc.L
-1
for sugarcane crop). The maximum simulated value
estimated under 300 cm deep watertable using S5, was 0.0145 molc.L
-1
. On other hand, using the highest mean value of
groundwater salinity in simulations (i.e 0.051 molc.L
-1
), enhanced the root zone salinity level up to and more than crop threshold
value, particularly under shallow watertable conditions. The maximum simulated values for scenario S5 (0.051 molc.L
-1
salinity)
estimated under 300 cm, 600 cm and 1150 cm deep watertables, were 0.0485 molc.L
-1
, 0.0283 molc.L
-1
and 0.0255 molc.L
-1
respectively. The results showed that there was a greater influence of capillary flux on root zone salt concentration than
irrigation water, the shallow saline watertable attributed greater root zone salinity due to more contribution through capillary
up flow.
Muhammad Kashif, Muhammad Arshad, Jehanzeb Masud Cheema, Ejaz Ahmad Waraich. (2020) MODELING ROOT ZONE SALINITY DYNAMICS USING INTEGRATED EFFECT OF SOIL, WATER, CROP AND CLIMATE FOR SEMI-ARID REGION, Pakistan Journal of Agricultural Sciences, Volume 57, Issue 3.
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