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Study Shows Profitability
Hybrid Rice Use Saves Water, GHG Emissions, Produces Yields
BETTY VALLE GEGG-NAEGER
MidAmerica Farmer Grower
JONESBORO, ARK.
People often think that environmental concerns were only for rich consumers and for government regulations. However, in reality, thoughts should turn to the County level percentage of 2009 water use sustainable for the Alluvial Aquifer, according to Dr. Lanier Nalley, Ag Economist with the University of Arkansas.
He cites several statistics to affirm his claim:
• In 2004, the Arkansas Natural Resources Commission (ANRC) estimated groundwater withdrawals at 24.6 billion liters per year, a 70 percent increase from the amount used in 1985 and over 12 times that of 1945 (ANRC, 2007).
• With water supplies declining at these rates, water-intensive agricultural production, such as rice production, are at risk for long run viability.
• Irrigated rice is a water-intensive crop, accounting for approximately 25 percent of total global annual freshwater usage (Dobermann, 2012).
• Rice is a staple food crop around the world, providing the primary source of calories for more than 50 percent of the world’s population (IRRI, 2012).
While one can see in terms of a tangible water source the effects of a declining aquifer, Greenhouse Gas Emissions (GHG) is something unseen, and the bad news is that GHG emissions from rice comes at the farm level.
Hybrid rice can change that picture since Hybrids can yield 15 to 20 percent more rice than conventional cultivars on similar land due to the combination of yield-improving genetic traits in parent cultivars. Also, Hybrids typically have shorter life cycles.
“Thus it stands to reason that hybrid cultivars require less time under flood, which, in return, likely equates to lower water usage and lower GHG emissions compared to conventional cultivars that have relatively longer growing seasons and require a greater duration of flooding,” Nalley said. “These characteristics would likely promote more sustainable rice production in Arkansas and the United States in general.”
A study was conducted to evaluate the effect of cultivar type (i.e., conventional and hybrid) on water-use efficiency (lbs of GHG/lb of rice) as well as GHG emissions (CH4 and CO2 used to pump water).
Based on seven consecutive years of cultivar-trial data in four locations that typify silt-loam-grown rice in Arkansas, it was hypothesized that the shorter vegetative stage of hybrids results in two distinct, positive advantages over conventional rice cultivars. One is a reduction in water needed to produce a unit of rice, and another is a reduction in CH4 emissions per unit yield produced.
“In calculating water use by variety, we used planting date, days to heading, and harvest date for over 600 varietal observations at the University of Arkansas ARPT locations from 2004-2010,” Nalley said. “We also had weather data for each location to calculate evapotranspiration rates for each variety at each location for each year.”
The field data on CH4 emissions obtained from Rogers et al. (2012, 2013) were used to estimate seasonal CH4 emissions based on the number of days under flood for each cultivar.
GHG from field operations and inputs include those from diesel fuel for tractor operations to apply fungicide, herbicide, pesticide, and fertilizer and from nitrous oxide (N2O) emissions which were estimated for each cultivar (McFadden et al., 2013).
The combination of these two above noted components yields a net carbon footprint by variety.
Results are that conventional varieties on average were found to release 23.22 percent more (P<0.05) GHG to produce a pound of rice compared to the average hybrid. Conventional varieties also, on average, were found to use 33.47 percent more (P<0.05) water to produce a pound of rice compared to the average hybrid. This is due to both lower average yields and longer days on flood.
This is of utmost importance given the decline of the Alluvial Aquifer and the fact there’s an increased need to feed a growing world, according to Nalley. From a hybrid rice producers’ standpoint, this is excellent material to give to vendors and possibly attempt to extract a premium.
Rice is a staple food crop around the world, providing the primary source of calories for more than 50 percent of the world’s population (IRRI, 2012).
A farmers’ job is important for feeding some of the poorest people in the world, and high GHG emissions cannot be allowed to stymie that effort. Ways are needed to reduce the nation’s water footprint so future generations have the opportunity to farm rice as well.
It’s also important to find ways to reduce GHG emissions to provide large retailer proof that the rice industry is actively pursing ways to lessen the GHG footprint. Regardless of individual belief, consumers are starting to demand products with environmental information associated with them.
Rice production in the United States has experienced increased pressure from private industry to reduce GHG emissions associated with rice production. Producers who supply global markets can expect to face increasing pressure from abroad regardless of demand or regulations here.
Lower water usage per unit of rice produced has the potential to have large marketing appeal for companies and potentially high consumer demand.
“In my mind the most agreeable definition of rice sustainability is having enough water to produce a crop, and in that sense, anything we can do to improve the efficiency of water is worth pursuing,” Nalley said.
Using the same data, he finds there is a yield advantage for using hybrid rice. The split between hybrids and conventionals was 32.43 bu/ac in this study. The difference between Clearfield hybrids and Clearfield was 33.94 bu/ac. These results provide revenue gains for producers.
Nalley’s take home message is that something must be economically and environmentally sustainable or producers simply will not adopt it.
“It appears that hybrid rice with its higher yields, lower water demands and lower GHG/bu of rice produced fits the mold of improving sustainability in both the economic and the environmental sense,” he summed. ∆
BETTY VALLE GEGG-NAEGER: Senior Staff Writer, MidAmerica Farmer Grower
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