High guayule rubber production with subsurface drip irrigation in the US desert southwest

Authors: Hunsaker, Douglas - Doug; ELSHIKHA, DIAA - University Of Arizona; Bronson, Kevin

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2019
Publication Date: 4/23/2019
Citation: Hunsaker, D.J., Elshikha, D.M., Bronson, K.F. 2019. High guayule rubber production with subsurface drip irrigation in the US desert southwest. Agricultural Water Management. 220:1-12. https://doi.org/10.1016/j.agwat.2019.04.016.
DOI: https://doi.org/10.1016/j.agwat.2019.04.016

Interpretive Summary: In recent years, US tire companies have invested significantly in development and commercialization of guayule in the arid US Southwest to supplement natural rubber supplies from Asia. A critical matter in making guayule both profitable and sustainable in this region is increasing its yields and water use efficiencies with improved irrigation methods, such as subsurface drip irrigation (SDI). This research conducted by ARS scientists in Maricopa, Arizona, provides the only technical information on how guayule responds to water when irrigated with SDI. The study shows that guayule growth and rubber yield increase with the amount of irrigation water given. However, it also showed that using half as much water with SDI will yield 24% more rubber than guayule grown with traditional surface irrigation methods. This research demonstrates how much more rubber yield commercial guayule growers can realize if they use SDI. Prediction models are also provided to allow growers to estimate expected yield when irrigation water is limited. The research will also be of interest to the US Rubber Industry, including Tire Manufacturers, irrigation consultants, water district water managers, and other research investigators of guayule.

Technical Abstract: Guayule is being produced for natural rubber in US desert areas, where irrigation requirements are high. Improved irrigation practices and methods are required to increase guayule yields and reduce its water use. Presently, there is no information available on guayule produced using subsurface drip irrigation (SDI). Therefore, we conducted an SDI guayule field study in 2012-2015 in Maricopa, Arizona, US. The objectives were to evaluate guayule dry biomass (DB), rubber yield (RY), and crop evapotranspiration (ETc) responses to water application level, and to compare these results to previously reported guayule irrigation studies. Guayule seedlings were transplanted in the field in October 2012 at 0.35-m spacing, in 100-m long rows, spaced 1.02 m apart. The field had 15, 8-row wide plots (5 irrigation treatments x 3 replicates). Irrigation treatments were imposed in a randomized complete block design starting in May 2013. Irrigation scheduling was based on the measured soil water depletion percentage (SWDp) of a fully-irrigated treatment, defined as 100% ETc replacement, and maintained at ˜20-35% SWDp. The other treatments received 25%, 50%, 75%, and 125% of irrigation applied to the 100% treatment on each day of irrigation. Destructive samples for dry biomass, rubber, and resin contents were periodically taken from each plot between February and November of each year until the guayule was bulk-harvested in March 2015. Results indicated ETc, DB, and RY increased with total water applied (irrigation + rain), which varied between treatments from 2080 to 4900 mm for the 29-month growing season. Final dry biomass and rubber yields of 61.2 Mg/ha and 3430 kg/ha, respectively, were achieved with the highest irrigation treatment level (125%) and these yields were significantly higher than those under all other irrigation levels. All SDI irrigation treatments except for the lowest 25% level had rubber yields from 24 to 200% greater than the maximum RY achieved under a companion surface irrigation study conducted simultaneously in Maricopa.