Abstract
A saline shallow water table can contribute significantly to salinity/sodicity development in the root zone. Field
investigation was carried out in saline-sodic soil (EC = 9.7 dS m', SAR = 32.4 (mmol L'1
)1/2 and pH = 7.9) to study
the effect of fluctuating water table on soil salinization/sodication under fallow and cropped conditions. Wheat and
maize were used as cover crops. The water table fluctuation was monitored through piezometer and it ranged
from 0.8 to 10 feet during the experimental period. Soil profile salinity /sodicity decreased with lowering of water
table and vice versa. Initially at 3.6 feet water-table depth the ECe of 0-30 cm surface layer was 9.7 dS m' which
decreased to 6.9 & 4.7 dS m' under fallow and maize crop, respectively when water table lowered to 8 feet.
During rabi season further lowering of water table to 10 feet decreased the ECe to 6.5 & 3.9 dS m' under fallow
and wheat crop. On the other hand ECe was increased to 11.4 & 10.2 dS rn' during kharif season by rising water
water-table to 2.1 feet and to 15 & 11.4 dS m ·1 during rabi season when water table rose to 0.8 foot. Almost
similar trend was found in other soil layers. Likewise SAR was decreased to 25.7 & 21 (mmol L'1
) 1/2 under fallow
and cropped conditions, respectively at 0-30 cm soil layer by lowering water table to 10 feet. Whereas it increased
to 44 & 36.5 (mmol L·1
)1/2 when water table rose to 0.8 foot. A small change in SAR of other soil layers was found
with water table fluctuation. The soil pH did not change much with changing of water table depth. The comparison
of fallow cropped plots indicated that decrease in soil salinity/sodicity with lowering water table was greater under
crop cover than fallow conditions.
Key words: water table, salinity, sodicity, salt movement.
