As the push for more biofuel crops remains strong, university researchers are looking into alternative crops that would be good for growing on marginal land.
Biofuel crops are most often relegated to marginal land since food crops are produced on the best land possible. However, the soil in marginal land is often salty, which is a significant challenge for producing any crops.
University of Illinois researchers are now experimenting with perennial grasses that can withstand salinity in marginal soils. The two main crops they are comparing are switchgrass and prairie cordgrass.
The research is showing that three prairie cordgrass accessions and one switchgrass cultivar showed tolerance to high salt conditions in terms of dry biomass production.
Soil salinity is a challenge for plants because high salt concentrations in the soil strip away water from the plants, which behave as if they are in a drought environment.
“Saline soils are characterized by high concentrations of soluble salts, such as sodium, chloride, calcium chloride, or magnesium sulfate, whereas sodic soils are solely characterized by their high sodium concentrations,” said D.K. Lee, crop scientist, University of Illinois explains. “Many soils are both saline and sodic.”
The researchers subjected six prairie cordgrass accessions and three switchgrass cultivars to different levels of sodicity and salinity over two years of growth. The team conducted a similar experiment in an earlier study, but only looked at one cordgrass (‘Red River’) and one switchgrass (‘Cave-In-Rock’) cultivar, over only one growing season.
“In that study, we found that ‘Cave-In-Rock’ switchgrass was not good at all in terms of salt tolerance. ‘Red River’ cordgrass was far superior,” Lee recalls.
The expanded study showed that prairie cordgrass had, on average, much higher germination rates than switchgrass in saline and sodic conditions. Dry biomass production was not as clearly split between the two species in salty conditions, however.
Three prairie cordgrasses, pc17-102, pc17-109, and ‘Red River’, and one switchgrass, EG-1102, produced equivalent amounts of dry biomass when subjected to high-salt conditions. However, they produced approximately 70 to 80 percent less biomass in salty conditions than they did with no added salt. In contrast, the salt-susceptible switchgrass cultivar, EG-2012, produced approximately 99.5 percent less biomass in high-salt treatments than it did without added salt.
The next step for the researchers is to bring this work out of the greenhouse, where climate is controlled and water is unlimited, to real-world scenarios. Preliminary field research has shown that prairie cordgrass is very successful in salt-affected areas in Illinois and South Dakota.