Performance of subsurface drip irrigation for improving root zone moisture in cotton

Abstract:

Cotton growers face a practical dilemma: surface drip systems waste water to evaporation, while furrow irrigation soaks the wrong soil zone. Subsurface drip irrigation (SDI) promises to deliver water directly to the active root zone, but at what depth does it work best? This research compared four irrigation methods-surface drip (control), SDI at 15 cm, SDI at 25 cm, SDI at 35 cm, and furrow irrigation (check)-for their effect on root zone moisture distribution, water productivity, and seed cotton yield of Bt cotton (cv. Bunny BG-II) on a clay loam soil at Birsa Agricultural University, Ranchi, Jharkhand, India, during kharif 2022 and 2023. A randomized block design with four replications was used. SDI at 25 cm maintained the most uniform root zone moisture (CV 11.3% vs. 24.8% for furrow), achieved the highest water productivity (0.68 kg m⁻³), and produced the best seed cotton yield (2, 486 kg ha⁻¹)-a 28.4% improvement over furrow irrigation. Root density at 15-30 cm depth was 34.7% higher under SDI-25 than surface drip. These results confirm that SDI at 25 cm depth is optimal for cotton on clay loam soils in the Jharkhand plateau region.