The Effect of Five Biomass Cropping Systems on Soil-Saturated Hydraulic Conductivity Across a Topographic Gradient
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The Effect of Five Biomass Cropping Systems on Soil-Saturated Hydraulic Conductivity Across a Topographic Gradient Usman Anwar 1 & Lisa A. Schulte 1 & Matthew Helmers 2 & Randall K. Kolka 3
Published online: 13 May 2017 # Springer Science+Business Media New York 2017
Abstract Understanding the environmental impact of bioenergy crops is needed to inform bioenergy policy development. We determined the effects of five biomass cropping systems—continuous maize (Zea mays), soybean (Glycine max)triticale (Triticosecale ×)/soybean-maize, maize-switchgrass (Panicum virgatum), triticale/sorghum (Sorghum bicolor), and triticale-aspen (Populus alba × P. grandidentata)—on soilsaturated hydraulic conductivity (KS) across a toposequence in central Iowa, USA. We compared data from the time of cropping system establishment in 2009 to 4 years post-establishment. Both our 2009 and 2013 data confirmed that cropping system impacts on KS vary by landscape position. We found that differences in cropping system impacts were more likely to occur at lower landscape positions, specifically, within footslope and floodplain positions. Previous research on cropping system impacts suggested that grass and woody systems were associated with a general increase in KS over time, with greater changes likely occurring at landscape positions with a higher erosive potential or lower SOC content. Our results confirmed that the triticale-aspen woody system was associated with a significant increase in KS across all landscape positions. In contrast, we did not observe an increase in KS under maize-switchgrass, which we attributed to the high
* Usman Anwar [email protected]
1
Department of Natural Resource Ecology and Management, Iowa State University, 339 Science II, Ames, IA 50011, USA
2
Department of Agricultural and Biosystems Engineering, Iowa State University, 1340 Elings Hall, Ames, IA 50011, USA
3
Center for Research on Ecosystem Change, USDA Forest Service, 1831 Hwy 169 East, Grand Rapids, MN 55744, USA
density of switchgrass roots by the fourth year of study, but expect an increase in KS under switchgrass under longer measurement periods. We also found a significant increase in KS in the annual systems, likely due to the conversion to no-till soil management with cropping system establishment. We expect such differences to become more apparent over longer time scales as cropping systems continue to impact soil hydraulic properties. Keywords Infiltration . Landscape biomass project . Maize . Soybean . Switchgrass . Woody biomass
Introduction The development of sustainable bioenergy systems will require the expansion and use of alternative biomass feedstocks with varying environmental impacts. Globally, the conversion of native perennial vegetation to annual crops has led to declining water quality, freshwater habitat, and biodiversity [1]. Increased cultivation of annual crops such as maize (Zea mays) has led to an increase in runoff, erosion, and nutrient losses [2]. In contrast, perennial bioenergy crops are associated with reduced nut
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