Green and blue water footprint reduction in irrigated agriculture: effect of irrigation techniques, irrigation strategies and mulching

D. Chukalla, M. S. Krol, and A. Y. Hoekstra

One of the important prospects for relieving increasing water scarcity is to reduce the consumptive water use in the agricultural sector, which makes up the largest share in global freshwater consumption. This study explores the effect of three management practices on the soil water balance and plant growth, using the AquaCrop model and the global water footprint (WF) standards. The management practices are four irrigation techniques (furrow, sprinkler, drip and subsurface drip (SSD)), four irrigation strategies (full (FI), deficit (DI), supplementary (SI) and no irrigation), and three mulching practices (no mulching, organic (OML) and synthetic (SML) mulching). Various cases were considered: arid, semi-arid, sub-humid and humid environments in Israel, Spain, Italy and the UK, respectively; wet, normal and dry years; three soil types; and three crops. For each management practice, the associated green, blue and total consumptive WF were compared to the reference case (furrow irrigation, full irrigation, no mulching). We found that the average reduction in the consumptive WF is 8–10 % if we change from the reference to drip or SSD, 13 % when changing to OML, 17–18 % when moving to drip or SSD in combination with OML, and 28 % for drip or SSD in combination with SML. Reduction in overall consumptive WF always goes together with an increasing ratio of green to blue WF. The WF of growing a crop for a particular environment is smallest under DI, followed by FI, SI and rain-fed. Growing crops with sprinkler irrigation have the largest consumptive WF, followed by furrow, drip and SSD. Furrow irrigation has a smaller consumptive WF compared with sprinkler, even though the classical measure of “irrigation efficiency” for furrow is lower.

The full paper was published in Hydrology and Earth System Sciences Journal

Published 4th January, 2016