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News Article

Could switchgrass provide fuel and help air quality in China?


Joint Chinese-American study suggests switchgrass as a biomass crop on the Loess Plateau

Switchgrass (Panicum virgatum) has been investigated since the 1980s as an energy crop for the United States and is suggested as a plant which can be grown on marginal land to reduce fossil fuel emissions, reduce erosion on marginal cropland, and enhance wildlife habitat. Now a joint study (Cooney et al., 2017) between researchers at the Northwest A&F University in Yangling, China, and the University of Illinois at Urbana-Champaign, is suggesting that it could also be grown as a biomass crop on the Loess Plateau in China. The agronomists say that switchgrass has potential to minimize land degradation and desertification and to generate biomass for energy. By binding the soil and replacing coal as a fuel, it could also have dual effects in reducing air pollution.

"China's poor air quality is caused by a combination of coal burning and particulates from soil erosion. The Loess Plateau is the major source of erosion in China, and air quality there is just terrible. If erosion in the Loess Plateau can be improved, air quality will improve," says D.K. Lee, an agronomist in the Department of Crop Sciences at the University of Illinois.

Although the region has been farmed for millennia, much of China's Loess Plateau could be described as a barren moonscape: dry, dusty, and prone to erosion. In fact, the distinctive loess soils in the area have been called the most erodible in the world, and around 70% of agricultural land in the area is on a substantial slope. In a massive soil conservation effort, the Chinese government is creating incentives for farmers to plant sustainable and erosion-reducing cropping systems, including orchards, forests, and perennial grasses. two policies, Grain for Green and Western Development Action have been established by the Chinese government. Researchers from U of I are recommending switchgrass.

Perennial grasses have gained attention as bioenergy feedstocks due to their high biomass yields, low inputs, and greater ecosystem services compared to annual crops. Moreover, perennial grasses limit nutrient runoff and reduce greenhouse gas emissions and soil losses while sequestering carbon. Additionally, perennial grasses can generate economic returns for local farmers through producing bioenergy feedstock or forage on marginal lands.

"When we're looking at revegetation, ideally we're planting something that can bring in revenue for farmers. Switchgrass produces a lot of biomass that can be harvested and burned as a cleaner source of energy," Lee says. "Not only can switchgrass reduce air pollution by holding the soil, if it is burned instead of coal, it can reduce air pollution in a second way."

Switchgrass is stress tolerant and small-scale testing in the area has shown that it can produce plenty of biomass even with limited irrigation and fertilizers. But, Lee says, cultivar selection and management practices will depend on where switchgrass is planted within the Loess Plateau. "Most areas should be okay, but elevation, latitude, and moisture level should be taken into account when selecting the appropriate switchgrass cultivar for the area."

Although switchgrass has been introduced in China, it hasn't caught on as a biomass crop yet. That's where the research team -- including experts in switchgrass cultivar selection, agronomy, and management -- comes in, and their new article provides this information in practical terms for future evaluation by Chinese scientists and government agencies.

"Stopping erosion in the Loess Plateau is not going to be easy. It was the birthplace of agriculture in Asia, and it has been farmed for several thousand years. The land has been intensively farmed. But when I visited, I saw people out there planting trees by hand. It's changing. And maybe switchgrass can be part of that change," Lee says.

Searching the Environmental Impact website for switchgrass and bioenergy, almost 1400 records are found, the majority from the USA. According to Mitchell et al. (2016), 25 years of research has demonstrated that perennial grasses like switchgrass are profitable and environmentally sustainable on marginally productive cropland in the western Corn Belt and Southeastern USA. But Gouzaye and Epplin (2016) suggest that restricting switchgrass production to marginal land increases the land requirement and increases the cost of delivering feedstock compared with if production can be also on higher quality land. Dumortier et al. (2016) report that the U.S. cellulosic biofuel mandate has not been enforced in recent years, and that uncertainty about enforcement  in addition to high production and harvest cost have contributed to a delay in the widespread planting of bioenergy crops such as switchgrass and miscanthus.

In China, attempts to reduce dependence on coal and improve air quality have led to investments in large biomass power plants. On the Loess Plateau, the governments of Shaanxi and Gansu provinces have announced and implemented policies called Planning for the Development of Bioenergy in Rural Areas from 2007 to 2020 and 2011 to 2015, respectively. Thus the policy environment in China may support production of biomass crops. Switchgrass has the advantage of having already been the subject of intensive research in the USA, although available cultivars would have to be evaluated for local climate and conditions.

The search “Loess Plateau” AND erosion currently also finds around 1400 bibliographic records on EI. There are a number of studies on the database on bioenergy crops such as switchgrass and miscanthus, and their potential for the region. Gao et al. (2017) report on photosynthetic performance and field productivity of switchgrass on the Loess Plateau. Ichizen et al. (2005) found that planting of switchgrass was effective against soil erosion in the hills of the Loess Plateau. Ma et al. (2011) compared various cultivars of switchgrass, and suggested that Cave-in-Rock and other upland cultivars with a high chromosome ploidy might be optimal choices for biomass plants. Wang et al. (2015) found in this region that switchgrass had a great potential to sequester C into soils with low N2O emissions while supplying significant quantities of biomass for biofuel synthesis.

Article details

  • Author(s)
  • David Simpson
  • Date
  • 07 September 2017
  • Source
  • University of Illinois College of Agricultural, Co
  • Subject(s)
  • Biofuels