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United States Department of Agriculture

Agricultural Research Service

Research Project: DETERMINING MAXIMUM SUSTAINABLE PRODUCTION OF BIOMASS WITH MIXTURE OF PRAIRIE SPECIES
2009 Annual Report


1a.Objectives (from AD-416)
The objective of this project is to determine the optimal mixture of native prairie vegetation for the most efficient means of sustainable production of biomass for electrical generation while maintaining wildlife habitat and other prairie conservation benefits.


1b.Approach (from AD-416)
We propose to develp a native biomass fuel mixture that will produce large quantities of biomass over a variety of margnal soil types under variable annual weather conditions. This mixture would also be easily established, persist in mixed stands for the long term (10-30 years), be harvested efficiently by machine, be easily processed and used in stocker furnaces for elecrical generation. The"biofuels prairie mix" will contain 16 species from at least five plant functional groups (C4 and C3 grasses, sedges, legumes and forbs). The "biofuels mix" will be compared with three other mixes: a control consisting of a pure stand of switchgrass, a stand of five species of productive warm-season grasses, and a "prairie reconstruction mix" comprised of 32 species typically used in prairie plantings. Treatments will be imposed in randomized, replicated plots, large enough for harvest with farm equiment and to provide sufficient material for test burning by Cedar Falls Utilities. The experimental design will be stratified by soil type. Baseline soil carbon data will be collected from the plots prior to planting prairie vegetation in the spring of 2008. Species composition, aboveground- and root biomass will be quantified in 2009, 2010, 2011, and 2012. Soil cores will be taken in 2012, to assess soil carbon changes under the vegetation treatments. Wildlife monitoring will begin in 2008 and continue through 2012.


3.Progress Report

The objective of this project is to develop a native biomass fuel mixture containing 16 prairie species appropriate for non-prime agricultural land. Biomass productivity and carbon sequestration potential will be compared with a switchgrass control, a prairie reconstruction seed mix, and one other seed mixture without added fertilizer or tillage. The experiment will be implemented at two research sites: an alluvial site located in the Cedar River Natural Resource Area (CRNRA) and an upland site located on the University of Northern Iowa (UNI) campus. Field plots at CRNRA were established in the fall of 2007 stratified by soil type for a total of 48 treatment plots, 16 on each soil type. In May 2008, three soil sampling sites were randomly selected within each treatment plot and geolocated. One soil core was removed at each sampling site within each plot using a truck-mounted Giddings soil probe to a depth of 120 centimeters and sectioned into five depth increments (0-15, 15-30, 30-60, 60-90, and 90-120 cm). Three surface soil cores were collected using hand probes from each sampling site within each plot and sectioned into two depth increments (0-7.5 and 7.5-15 cm). The three cores per sampling site were composited by depth increment prior to processing for biological and chemical analysis. The entire experimental site was flooded in June 2008 and remained under water for several weeks. Since significant surface soil erosion and deposition occurred as a result of the flooding, the surface sampling was repeated in May 2009. Deep core samples from May 2008 were processed and prepared for analysis in the summer of 2008 and chemical analysis began winter 2008/2009 and is continuing through 2009. Surface soil samples taken in May 2009 were processed and prepared for analysis in June 2009. Sixteen field plots (0.25 ha each) were established at the UNI site in April 2009 in ten-year old alfalfa/cool season grass pasture. Grasses were killed with glyphosate on May 8, 2009, and one soil core was removed from the center of each plot on June 4, 2009, using a truck-mounted Giddings soil probe to a depth of 120 centimeters and sectioned into five depth increments (0-15, 15-30, 30-60, 60-90, and 90-120 cm). Surface soil cores were collected as described previously. Deep core and surface samples were processed and prepared for analysis in June 2009. Monitoring activities for this project include quarterly conference calls with UNI collaborators, field site visits 1-2 times per year, and a yearly meeting for data sharing with stakeholders and graduate students.


Last Modified: 8/29/2014
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