Soil water balance studies in subsurface drip irrigation for amaranthus

Abstract

Subsurface drip irrigation (SDI) is advanced drip irrigation where the tubing and emitters are buried beneath the soil surface. Field experiment was done at the instructional farm, KCAET, Tavanur. Experiment was aimed to optimize the depth of installation of laterals and spacing between laterals under subsurface drip system. This study also computed deep percolation from different layers with different lateral depths. Soil moisture was taken from different depths and horizontal distance and soil moisture contour maps were plotted. Results showed that moisture content increased with depth from the surface due to less evaporation loss. Also, amount of moisture was found to be decreased with time. Moisture content at the surface layer for 10 cm lateral was 14.5 per cent whereas the same for 20 cm lateral was 11.6 per cent due to surfacing. Moisture distribution pattern was uniform for lateral with 15 cm depth. Maximum values of yield were observed for the treatment T4, and then T1 (which have 15 cm and 10 cm lateral depth respectively). Highest water use efficiency was for treatment T4 with a value of 37.96 kg/ha-mm followed by treatment T1 with 34.6 kg/ha-mm. In statistical analysis, it was observed that, there were significant variations between treatments. Number of leaves was influenced by both spacing between laterals and depth of laterals. Stem girth was varied significantly by spacing between laterals. Both spacing between laterals and lateral depth had remarkable effect on crop height. Deep percolation was relatively less from the surface layers than from the deeper layers in higher lateral depths (i.e., 20 cm lateral depth). From this study, it is evident that treatment T4 (lateral spacing = 95 cm, lateral depth= 15 cm) has showed maximum response while considering moisture distribution, crop yield, biometric properties and deep percolation.