Distribution and Quantity of Root Systems of Field-Grown Erianthus and Napier Grass

Abstract

Cellulosic bioethanol produced from non-edible plants reduces potential food-fuel competition and, as such, is receiving increasing attention. In the raw material production of cellulosic bioethanol, the aboveground biomass of plants is entirely harvested; consequently, the plant roots represent the major source of organic matter incorporated into the soil. We selected Erianthus and Napier grass as the raw materials for cultivation in Asia. However, information about whether these 2 species provide sufficient root volume to sustain soil fertility is limited. Therefore, we examined the spatial distribution of the roots of these 2 plants, and quantified root mass and length. Erianthus and Napier grass were either grown in fields or greenhouses in Tokyo (Japan) and Lampung (Indonesia), and then their roots were exposed from adjacent soil profiles. Both species developed large, deep roots, penetrating 2.0 -2.6 m deep into the soil. Root depth indexes showed that the roots of both species penetrated much deeper into the soil compared to monocot crop species, being more comparable to dicot species. Erianthus developed a root mass and length of 384 -850 g·m −2 and 28.8 -35.8 km·m , respectively. These values exceeded the maximum values previously recorded for common crop species. Our study confirmed that Erianthus and Napier grass develop deep root systems, with substantially large biomass; hence, we suggest that both plants supply root biomass in large quantities, representing possible major sources of soil organic matter.

Cultivation of <i>Erianthus</i> and Napier Grass at an Abandoned Mine in Lampung, Indonesia

“…Indeed, switchgrass increased SOC several years after it was established [28], due to its large root system [29]. In our previous report, we argued that Erianthus and Napier grass may positively affect SOC because they develop large and deep root systems [30]. The results of the second trial in the present study should support our claim, although prolonged monitoring is necessary in order to draw a certain conclusion.…”

Forage grass cultivation increases soil organic carbon and nitrogen pools in a karst region, southwest China

“…Because most of the aboveground biomass in the agricultural fields were harvested while the belowground biomass inputs were not measured, we cannot judge the difference in organic matter inputs among the agricultural land uses. Nevertheless, some evidence shows that the perennial grasses usually have significantly higher root biomass relative to soybean or maize (Jarecki & Lal, 2003;Lemus & Lal, 2005;Sekiya, Shiotsu, Abe, & Morita, 2013). For example, a field survey shows that the root weight and length range from 183 to 448 g m −2 and 15.6 to 43.6 km m −2 , respectively, much higher than the values for sugarcane (~158 g m −2 and 14.6 km m −2 ) or maize (~15.1 km m −2 ) (Sekiya et al, 2013 cultivation on fallowed soil (Ma et al, 2000).…”

“…Nevertheless, some evidence shows that the perennial grasses usually have significantly higher root biomass relative to soybean or maize (Jarecki & Lal, 2003;Lemus & Lal, 2005;Sekiya, Shiotsu, Abe, & Morita, 2013). For example, a field survey shows that the root weight and length range from 183 to 448 g m −2 and 15.6 to 43.6 km m −2 , respectively, much higher than the values for sugarcane (~158 g m −2 and 14.6 km m −2 ) or maize (~15.1 km m −2 ) (Sekiya et al, 2013 cultivation on fallowed soil (Ma et al, 2000). According to a data synthesis of 23 data points, an SOC accumulation rate of about 1.01 Mg C ha −1 yr −1 can be obtained by converting cropland to pasture (Conant, Paustian, & Elliott, 2001).…”

Variation of Morpho-Agronomic and Biomass Quality Traits in Elephant Grass for Energy Purposes According to Nitrogen Levels

“…Recently, because of its high biomass production potential, another use for elephant grass has been proposed: its transformation into firewood [1], which may replace the wood extracted in a predatory manner from native forests, thus preventing environmental damage such as ravaging of forests, erosion, siltation, and death of several rivers. The biomass has gained great attention as a new source of sustainable energy alternative to petroleum-based fuels [2], in addition to also working in the carbon sequestration [3].…”