CHEMICAL PROPERTIES OF SALT AFFECTED SOIL AND YIELD OF SUGARCANE IN RELATION TO WATER TABLE DEPTHS IN MARDAN SCARP AREA

A field experiment was carried out to study the impact of different water table depths (WTD) on the chemical properties of soil and yield of sugarcane in Mardan SCARP area from September, 2000 to May, 2001. Five drainage units such as 106, 107, 108, 122 and 129 were selected in which observation wells were installed to monitor the water table depths. Soil samples from 0-30 cm depth were collected for the chemical analysis of electrical conductivity (Ece), sodium adsorption ratio (SAR) and soil reaction (pH). All the required data were collected at the head (H), middle (M) and tail (T) of the selected collectors in each drainage unit. The average WTD of drainage units 106, 108 (farmers’ controlled collectors), 122 (badly managed blocked collector), 107, and 129 (well managed free flowing collectors) were 1.67, 1.53, 1.16, 2.17 and 1.9 m, respectively from the ground surface. There was a rising trend in WTD at the tail of the blocked collectors. The average WTD of free flowing drainage units were relatively deeper than blocked ones. The average ECe, SAR and pH were in the range of 0 .73–2.3 dS m-1, 1.2–8.2 and 6.96–9.13, respectively in the selected drainage units. The ECe, pH and SAR were highest in the badly managed blocked drainage unit, while ECe and pH were lowest in free flowing drainage units. Average yield of sugarcane in all the above mentioned drainage units were in the range of 36.99–52.00 t ha-1and was highest in one of the farmer’s blocked drainage unit and lowest in badly managed blocked drainage unit. The yield of sugarcane was optimum at a WTD of 1.2-1.9 m and lowest at 1 m or 2 m from the ground surface. The overall results indicated that an optimum sugarcane yield can be obtained in Mardan SCARP area by maintaining water table from ground surface in the range of 1.2–1.9 m.