Environmental impacts of converting cropland to short-rotation woody crop production: First year results

Projections for the use of biomass power indicate that by the year 2010 up to 20 GW of electric capacity could be on line. Successful achievement of this goal would require the establishment of a dedicated biofuels feedstock. The Southeastern US has potential for production of biofuels but prior to widespread production of crops for biofuels, there is a need to assess potential environmental impacts. Displacement of traditional row crops by energy crops is likely to affect erosion, hydrology, water quality, and soil quality. A cooperative study was begun in 1995 at three locations to compare the impacts of converting row crops (corn and cotton) to short-rotation-woody-crops (SRWC). Initial results show minimal impact of converting to tree crops on runoff volumes and sediment during the first year. However, one site planted with cottonwood which has already reached canopy closure and is beginning to form a litter layer, is beginning to show marked reductions in runoff in the spring of the second year of the study. Runoff from a spring rainfall event after tree leaf-out was reduced from 25,000 liters in the cotton crop to only 1000 liters in the tree plots. First-year data also indicate that nitrate concentrations in runoffmore » water and soil leachate collected in lysimeters 1.5 m below the soil surface are higher in nitrate with N fertilized row crops than with SRWC and in some instances exceed the US EPA limit of 10 mg L-1.« less