Effect of the optimized regulated deficit irrigation methodology on water use in garlic

Authors: LELLIS, BRUNO - University Of Castilla-La Mancha(UCLM); MARTINEZ-ROMERO, ANGEL - University Of Castilla-La Mancha(UCLM); Schwartz, Robert; PARDO, JOSE - University Of Castilla-La Mancha(UCLM); TARJUELO, JOSE - University Of Castilla-La Mancha(UCLM); DOMINGUEZ, ALFONSO - University Of Castilla-La Mancha(UCLM)

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2021
Publication Date: 10/27/2021
Citation: Lellis, B.C., Martinez-Romero, A., Schwartz, R.C., Pardo, J.J., Tarjuelo, J.M., Dominguez, A. 2021. Effect of the optimized regulated deficit irrigation methodology on water use in garlic. Agricultural Water Management. 260. Article 107280. https://doi.org/10.1016/j.agwat.2021.107280.
DOI: https://doi.org/10.1016/j.agwat.2021.107280

Interpretive Summary: Reduced water availability for agriculture and increased energy costs make it necessary to improve crop water productivity. Under water-scarce conditions, crop water requirements often cannot be met throughout the growing season. This study by scientists from ARS (Bushland, Texas) and University of Castilla La Mancha used a strategy to allocate a limited volume irrigation water to improve water use efficiency of a high value crop, purple garlic, in Albacete, Spain. Garlic yield decreased with decreasing irrigation. However, water productivity was greatest when the volume of water applied was 70% of full irrigation. In addition, water applications were regulated so that they were greatest during the yield-sensitive bulb formation growth stage. Regulated deficit irrigation at 70% of full irrigation improved water productivity and reduced the water footprint associated with surface and groundwater. These results provide a framework by which water resources can be allocated to different crops to maximize returns from applied irrigation water and thus are of interest to stakeholders in other areas facing water scarcity issues, including the Texas High Plains.

Technical Abstract: The continuing decline in water availability for agricultural uses and increased energy costs have made it necessary to improve water-use efficiency in crops. The optimized regulated deficit irrigation (ORDI) methodology was developed to maximize the yield of annual crops under water-scarce conditions, either by reaching a specific deficit target or distributing a limited volume of irrigation water throughout the growing season (ORDIL). The objective of this study was, for a limited amount of available irrigation water, to determine the effect of ORDIL methodology on yield, agronomic water productivity and water footprint of a purple garlic cultivar crop under semi-arid conditions. To this end, five irrigation treatments were evaluated from 2015 to 2017 on an experimental farm located in semi-arid conditions (Albacete, Spain): no deficit (ND) (control), and four with different volumes of available irrigation water, corresponding to 100% (T100), 90% (T90), 80% (T80), and 70% (T70) of garlic net irrigation requirements (2750 m3 ha-1) for the weather conditions of the intermediate typical meteorological year. Yield decreased with increasing deficit, being up to 25% less for T70 compared with ND. However, the T70 ORDIL treatment attained the greatest average irrigation water productivity (5.30, 4.32 and 2.53 kg m-3 for 2015, 2016 and 2017, respectively) and the lowest average water footprint (349, 416 and 631 m-3 mg-1), while ND exhibited the greatest total water footprint in the process (18, 14 and 4% greater than T70).