The Effect of Landscape Position on Biomass Crop Yield

Integrating annual and perennial crops at the field scale creates new opportunities for increasing financial return while addressing important environmental and ecological issues. An understanding of biomass productivity on specific landscape positions is essential to realizing this goal. The objective of this research was to determine the effect of landscape position on the productivity of herbaceous and woody biomass crops. Alfalfa (Medicago saliva L.), corn (Zea mays L.), willow (Salix spp.), cottonwood (Populus deltoides W. Bartram ex Marshall), poplar (Populus maximoiviczii x P. nigra), and switchgrass (Panicum virgatum) were planted on seven landscape positions. Soil attributes were measured and included soil nitrogen, P, K, and profile darkness index (PDI). Terrain attributes included specific catchment area (SpecCat) and compound terrain index (CTI). A hierarchical Bayesian approach was used to analyze spatial data. Corn grain and stover yield was lowest in depositional and flat areas that retain water for longer periods of time and highest on well drained summit positions. Corn stover yield was positively correlated to nitrogen, PIN, SpecCat, and CT!, whereas corn grain yield was not correlated to any of the soil or terrain attributes tested. Conversely, willow productivity was among the highest at the depositional position and lowest at the summit position. For SX67 willow, growth was positively correlated to SpecCat, whereas 9882 willow growth was negatively correlated to PIN and CTI. Alfalfa and poplar productivity was highest at a site characterized by a relatively steep slope with potentially erosive soils.