The study water table fluctuation in tidal lowland for developing agricultural water management strategies: (A case study for corn cultivation after rice)

The research objective is to evaluate the water status in the tertiary block of tidal lowland for developing water management strategies and cropping pattern for food crop agriculture. The field study was conducted at reclaimed-tidal lowland areas having A typology (wet) located at Telang Karya Village, Primer 8, Delta Telang I. The method used was field action research. Corn was cultivated as a second crop indicator. For corn cultivation, the soil condition should be dry in which the water should be at the depth of 40-50 cm. The main point for network improvement is by construction of water gates at tertiary canal. These water gates are capable to hold high tidal water which made low tidal water can be drained in longer period. This in turn created dry land condition for corn cultivation. Potential planting was at dry season about the last June or early July. The best land drainage design was by providing drainage spacing at 8 m and the depth of 20 cm. Field study showed that operation of water gates have function to drain water from land during low tidal water and to retain water during high tidal water. The opening of water gates for water supply was done 3-4 times after corn plants were two-weeks old, one month, and during early seed filling period. The water table height was kept at 60 cm from soil surface in order to prevent the plant from experiencing water stress. Therefore the water management objectives for second crop were drainage option and in combination with control drainage. Supply water also required, especially in the early of flowering stage. The crop yield was highly potential with magnitude of 3-4 ton/ha and it was economically profitable because its B/C ratio was 1.4 which was close to the yield of rice cultivation farm enterprise.