Guayule Production in the Arid Southwest
Abstract
Declining water availability for agriculture in the Southwestern United States necessitates new strategies to sustain rural economies. High-valued crops that are drought and heat tolerant, grow on marginal lands, and provide economic returns will be important under variable future climate predictions. Guayule has been identified as a crop that can grow under these restraints, but has never proved to be economically viable in an intensive farming system. SBAR's collaborative effort is working to develop this production system and create a stronger economy in rural Arizona.
Background
Guayule is a rubber producing desert shrub that has been a commercial source of rubber since the 1800's. Its use after the Mexican Revolution was limited to periods when access to rubber from the Hevea rubber tree was restricted due to war, political unrest or exorbitant oil prices. During these periods research and production of this crop were increased greatly only to be shelved when access to Hevea rubber was once again restored. A new effort has begun with Bridgestone Americas as the industrial driver to develop the guayule rubber industry. In support of this new bioeconomy in Central Arizona, we have developed a multifaced research and delivery program to support this industry and finally make this entire production system a realization by:
Building on past research.
Collaborating with Bridgestone to identify and fill knowledge gaps in guayule production.
Use field crop Extension information pipelines to educate stakeholders.
Build economic sustainability analysis, define irrigation water requirements and develop valuable secondary products along with guayule education and extension programming through the Sustainable Bioeconomy for Arid Regions (SBAR) USDA grant.
The development of an entirely new economy requires tens of millions of dollars, decades of research and education and a solid industry to use the new product. The monumental achievement of developing a new commercial production system may be in the near future.
-Left guayule plant in a production field.
-Top of page Guayule in bloom. (Photo Credit Bridgestone)
In 2011, Bridgestone set out on a new journey, launching a research initiative aimed at diversifying the world's natural rubber supply. To help accomplish the goal, Bridgestone built the Biorubber Process Research Center in Mesa, Arizona. beginning production in September 2014. The team of experts on this 10-acre research campus are working to pioneer the commercialization of tire quality natural rubber derived from guayule, grown in the US. Through this innovation project and others like it, Bridgestone is reshaping the way the tire and rubber industry does business and moving closer to its long-term vision of manufacturing products from raw materials that are fully renewable and sustainable by 2050.
Bridgestone Americas
The Long-Term Vision from Bridgestone is to produce a Sustainable, Biologically diversified, and Geographically Diversified source of natural rubber. From the 281-acre Bridgestone Guayule Research Farm in Eloy, Arizona they have focused on the breeding and genetics, agronomy, and relationships with growers for guayule improvement to accomplish this.
Bridgestone collaborates with both private and public researchers to achieve the goal of a commercial rubber extraction plant and an economically viable growing system by mid to late 2020's. Bridgestone's collaborations can be seen in every facet of both Cooperative Extension research and education as well as an integral member of the SBAR grant. Bridgestone is a true industry leader in the development of a domestically produced natural rubber source.
Extension Events
We hold an annual Guayule Grower Field Day at the Bridgestone Guayule Research Farm to share new scientific finding and discuss the progress Bridgestone and SBAR have made towards commercialization of this desert shrub. We cover all areas of management and give potential growers an understanding of what should be expected when commercial acreage production is required. This year SBAR researchers present on both weed management, and economic viability. These and other studies have been showcased at multiple field days and will continue to be shared with our growers through all Extension platforms.
Weed Management
Guayule is a desert adapted perennial shrub with slow seed germination and seedling growth that are not competitive with Arizona’s fast growing annual weeds. However, once canopy closure occurs in the seed-row, guayule is competitive against weed seedlings. Additionally, guayule leaves have thick cuticles with leaf hairs that confer some tolerance to some postemergence herbicides.
Guayule herbicide tolerance studies have identified several preemergence and postemergence herbicides that can be safely used to provide weed control during establishment and early crop growth.
Postemergence herbicides
· Guayule is resistant to the selective grass herbicides fluazifop-p-butyl (e.g., Fusilade DX), sethoxydim (e.g., Poast), and clethodim (e.g., Select). These herbicides can be sprayed topically at any guayule growth stage to control annual and perennial grasses.
· Four true-leaf and larger guayule seedlings are tolerant of the contact burn-down PPO (protoporphyrinogen oxidase) inhibiting herbicides such as carfentrazone (e.g., Aim). There is some leaf injury but the plants are able to grow out of the injury in good growing conditions.
· Research is being conducted to identify additional preemergence and postemergence herbicides for broadleaf weed control.
Preemergence herbicides
· Metolachlor (Dual Magnum) and sulfentrazone (Spartan) are safe up to 2X normal rates in both sandy loam and clay loam soils. They can be sprayed topically after planting and incorporated with sprinklers or can be shallowly incorporated on the bed-top prior to planting.
· Acetochlor (Warrant) and bensulide (Prefar) are safe up to 2X normal rates when shallowly incorporated on the bed-top. If they are applied preemergence after planting and incorporated with sprinkler irrigation there is some stand loss but good crop populations can still be obtained at 2X and lower rates.
· Ethalfluralin (Sonalan) and pendimethalin (Prowl H2O) are safe at 2X normal rates and lower when mechanically incorporated into the soil. Preemergence use (i.e., sprayed after planting and incorporated with sprinkler irrigation) causes loss of plants in sandy loam soils but there is much less loss in clay loam soils. Thus, rates need to be adjusted according to soil type especially when the herbicides are applied preemergence. Guayule seedlings may grow slower initially in sub-optimal growing conditions such as in cold soils.
Current research is focused on developing weed control programs combining these herbicides and cultivation during stand establishment followed by early season carfentrazone and fluazifop-p-butyl to control escaped broadleaf and grass weeds, respectively. As the plants get larger and the canopy in the seed-row begins to close, cultivation, and post-directed, pre- and post-emergence herbicide sprays with a hooded sprayer can be used to maintain weed control.
Sbar Lead-Bill McCloskey
-Right freshley cultivated guayle field. (Photo Credit for both Dr. Bill McCloskey.)
Economic Viability
The introduction of any new crop into a current production system is always a difficult balance between current production practices, existing commodity markets and the economic impact the adoption will have relative to the current profits of the operation. Additional challenges occur due to imperfect market information as the local market may not exist for the new crop being evaluated. Understanding these changes are often difficult and for farmers interested in expanding crop options that might support rubber and biofuel industries, guayule could be one option. To effectively evaluate the potential adoption of this crop, we have developed two tools which allow producers to make more informed decision about the economics and overall fit of the crops into their operation. Using both the whole farm analysis tool and the budget enterprise tools allow producers to evaluate the net returns to the operation given varying levels of acreage adoption, crop mixes and changes in production inputs their by allowing the producer to make an more informed decision about the economics and overall fit of the crops into their operation.
Sbar Lead-Trent Teegerstrom
Above post processing products of guayule. Orange square rubber, green square bagasse, blue square resin. (Photo Credit Bridgestone)
Irrigation Research
Irrigation water supply is of the utmost importance in desert agriculture. Extended drought and loss of agricultural use water from the Central Arizona Project in 2030 will undoubtedly curtail crop production in Central Arizona. To better understand the intersection of economic guayule production and irrigation water requirements, SBAR researchers have begun several irrigation experiments. Guayule field irrigation experiments at Maricopa and Eloy research farms yielded the following significant results on the water demand and water implications on this desert shrub.
1. Rubber and resin contents (%) decreased with increasing water application rate, but rubber yield increases in sandy soil and decreases clay soil. (Graph 1)
2. Irrigation rate should not exceed 100% of estimated ETc for sandy loam and 75% of ETc in clay soils.
3. The sandy loam soil had much higher rubber yields than the clay soil for both irrigation systems at 100% application rate, but similar yields at 75% application rate
A remotely accessible sensor system was developed to measure soil moisture and evaluate crop stress to evaluate irrigation experiments.
An irrigation computer model, WINDS (Water-use, Irrigation, Nitrogen, Drainage, and Salinity), was modified to evaluate data from Eloy (clay soil, drip and flood) and Maricopa (sandy loam soil, drip and flood) experiments.
SBAR Lead-Peter Waller
-Thanks to Diaa El Shika, Hadiqa Maqsood, Danielle Murdoch-Hoare and Matt Katterman
SBAR Mission
The Sustainable Bioeconomy for Arid Regions (SBAR) Center of Excellence was established in September 2017, with the intended purpose of developing a systems approach for feedstock development, production, and delivery in the Southwest United States. It is further enhanced by the development and implementation of education, extension and outreach to teachers, 4-H youth groups, and farmers across the region.
SBAR works to optimize and integrate the production of guayule to enable the Southwest United States to significantly impact high-value product markets. Scientists are collaborating on research, development, and deployment (RDD) activities to:
Improve feedstocks and produce them in a sustainable manner;
Identify new value-added co-products that increase marketability;
Understand how conversion to fuel is affected by variable feedstock quality; and
Augment transportation, techno-economic, and sustainability models to provide a clear path to commercialization.
SBAR Vision
To provide stakeholders, interested in expanding crop options that support the rubber and biofuel industries, with regional solutions that are economically viable, socially acceptable, and meet the water conservation needs of the arid Southwest (AZ, CA, NM, and TX).
Blase Evancho
Assistant-in-Extension Pima & Pinal Counties
Blase is an agronomist working on field crops with a keen interest in alternative cropping systems. His primary projects include cotton variety testing, cotton heat stress, alfalfa heat stress and plant pathogen suppression in addition to his work on guayule.
Bill McCloskey - Extension Weed Specialist, Retired
Trent Teegerstrom - Associate Director for Tribal Extension Programs Ag Economics Extension Specialist: Production Economics, Crop Budget Development & Risk Management Education
Peter Waller - Associate Professor, Ag & Biosystems Engineering
Dave Dierig - Sec. Manager, Agro Operations, Guayule Research, Bridgestone Americas, Inc.
The entire SBAR cohort https://sbar.arizona.edu/our-story/our-team
Bridgestone Americas, inc.-https://www.bridgestoneamericas.com/en/index