Unintended consequences of biofuels production?The effects of large-scale crop conversion on water quality and quantity

Abstract

I n the search for renewable fuel alternatives, biofuels have gained strong political momentum. In the last decade, extensive mandates, policies, and subsidies have been adopted to foster the development of a biofuels industry in the United States. The Biofuels Initiative in the Mississippi Delta resulted in a 47-percent decrease in cotton acreage with a concurrent 288-percent increase in corn acreage in 2007. Because corn uses 80 percent more water for irrigation than cotton, and more nitrogen fertilizer is recommended for corn cultivation than for cotton, this widespread shift in crop type has implications for water quantity and water quality in the Delta. Increased water use for corn is accelerating water-level declines in the Mississippi River Valley alluvial aquifer at a time when conservation is being encouraged because of concerns about sustainability of the groundwater resource. Results from a mathematical model calibrated to existing conditions in the Delta indicate that increased fertilizer application on corn also likely will increase the extent of nitrate-nitrogen movement into the alluvial aquifer. Preliminary estimates based on surface-water modeling results indicate that higher application rates of nitrogen increase the nitrogen exported from the Yazoo River Basin to the Mississippi River by about 7 percent. Thus, the shift from cotton to corn may further contribute to hypoxic (low dissolved oxygen) conditions in the Gulf of Mexico.

Quantitative attribution of major driving forces on soil organic carbon dynamics

“…Out study indicated that this land management change could enhance the SOC sequestration, mitigating anthropogenic CO 2 emissions (see Sections 3.2 and 3.3). However, the intensified corn growth would decrease the water availability due to the higher water consumption by corn and likely worsen the hypoxia in the Gulf of Mexico because of the higher nutrient loads resulting from the higher fertilization rate for corn when compared to other small grains (e.g., soybean) [ CWIBP , 2008; Thomas et al ., ; Welch et al ., ; Wu et al ., ]. Therefore, increasing corn growth frequency is still a double‐edged sword strategy in terms of environmental protection, causing conflict in CO 2 mitigation and water resources protection.…”

Identifying potential areas for biofuel production and evaluating the environmental effects: a case study of theJamesRiverBasin in theMidwesternUnitedStates

“…The simulated environmental impacts of the case study are generally consistent with other published studies (CWIBP, ; Simpson et al ., ; Thomas et al ., ; Baskaran et al ., ; Ng et al ., ; Vanloocke et al ., ; Welch et al ., ; Love & Nejadhashemi, ). However, this study further addresses the connections between biofuel production and environmental cost (in terms of water quality) by elaborating on the relationship of biomass production and the resulting nitrogen load against switchgrass planting acreage and locations (Figs ).…”

Policy options to address global land use change from biofuels

“…Other biofuel LUC issues and concerns, in addition to increased GHG emissions, are higher or more volatile food prices, which hurt the poor (FAO, 2008;FAO et al, 2011); conversion of high biodiversity areas; overuse or degradation of water or land resources; damage to important ecosystem services (Koh and Wilcove, 2008;Donner and Kucharik, 2008;Welch et al, 2010); and disruption of land ownership or other social patterns (Toulmin, 2009). LUC impacts can also be positive, depending on location and management practices: biofuel LUC can improve resource productivity, sequester carbon, and provide additional income for rural populations (Tilman et al, 2009;Berndes et al, 2010).…”