Alley Cropping Systems for Biomass Production in River Floodplains.

Lignocellulosic biofuels are more sustainable than corn or other food crops based biofuel production.  However, the food versus fuel debate could still persist in terms of land resources devoted to each segment of crops. As a result, development of sustainable biofuel production systems without competition with prime agricultural land is necessary. Alley cropping systems consisting of perennial woody and herbaceous species has been suggested as an alternative biofuel production systems in river floodplains. Recent studies have reported that marginal lands in the Midwestern United States has the potential to produce up to 6 billion gallons of renewable biofuels each year. In this study, we evaluated the establishment of a large scale biomass alley cropping system in a river floodplain. Three perennial herbaceous species (Big bluestem - Andropogon gerardii, Indian grass - Sorghastrum nutans, switch grass - Panicum virgatum, plus a mix of all three) were planted in four poplar (Populus spp) alleys. To better evaluate the best alley cropping configuration, four different orientations were established  to compare the resource (e.g. light) utilization. The experimental design was a randomized split plot arrangement with three replicates for each configuration. Five short-rotation poplar (SRP) double rows 60 m long and 18 m apart were established with four alleys in between. Establishment of trees were impacted in patches where ponding occurred. The native vegetation was persistent and it may be necessary to use alternative methods to control them. However, once established such biomass alley cropping systems would be important for dedicated supply of biomass feedstock.