Water footprint assessments were conducted for dehydrated onions and micro-irrigation systems (MIS), produced by Jain Irrigation Systems Ltd. in Maharashtra, India. A key objective was to understand the differences in the water footprints between onions grown under drip and flood irrigation, both in terms of water usage and agricultural productivity. The team was also interested in the practical application of the assessment methodology for understanding the sustainability of water use throughout the supply chain, and for formulating appropriate response actions.
Groundwater is the primary source of irrigation water in the study region, and flood irrigation is the predominant irrigation practice. The area under irrigation has increased significantly over the past several decades. The positive benefits of this groundwater use including increased crop productivity and farm incomes are well documented, but adverse impacts from over-exploitation of groundwater are also recognized. The region has experienced a decline in groundwater levels of more than four meters since 1980, and wider use of drip and microspray irrigation is recognized as one measure to reduce non-beneficial evaporation during the dry season.
LimnoTech worked with Jain to collect required data and applied the methodology of the water footprint network. This is the first pilot study to address all four phases of a water footprint assessment.
Onions grown under drip irrigation were found to have a 42% smaller water footprint than onions grown under flood irrigation and a 35% increased yield. The grey water footprint for drip-irrigated onions is almost 90% smaller than for flood-irrigated onions, reflecting the reduced application requirements and lower leaching rate under drip irrigation.
The primary factor leading to groundwater depletion is expansion of the area of irrigated lands over the past four decades, particularly with water-intensive crops. The response strategies formulated through this project include increasing the rate of conversion from flood to drip irrigation, promoting less water-intensive cropping strategies and rainwater harvesting/aquifer recharge projects, and building collaboration between local water stakeholders to work toward sustainable water resource management in the region.