SIMULATING SOIL SALINITY AND SODICITY PROCESSES IN THE UNSATURATED ZONE USING LEACHM

Proper management of salinity and sodicity problems in irrigated areas requires a comprehensive understanding of the processes which control the movement of water and salt through the root zone of irrigated soils. This detailed understanding requires the knowledge of chemical reactions taking place in the soil profile when irrigation water moves through the soil profile. In the present study, an existing soil moisture chemistry mode, LEACHM ( Leaching Estimation And solute transport CHemistrv Model ) was employed to simulate soil moisture flow and solute transport in irrigated soils of Chishtian Irrigation Sub-division of Punjab, Pakistan.This paper shows the results of model simulations with LEACHM on soil salinity and sodicity using the data of climate, soil, crop and irrigation of Chishtian Irrigation Sub-division. The results of the study indicate that LEACHM simulates the processes of salinity and sodicity fairly well. The results also show that by using bad quality tubewell water for irrigation, the degradation of top soil may take place within one year time period and entire soil profile may get spoiled within a ten year time period