1. Soil & Environmental Responses to Dedicated Bioenergy Crops on Marginally Productive Croplands
Humberto Blanco, Associate Professor, Applied Soil Physics and Soil Management, Department of Agronomy and Horticulture, University of Nebraska-Lincoln, NE
Robert Mitchell, Research Agronomist, USDA-ARS
Virginia L. Jin, Research Soil Scientist with USDA-ARS

3. THREE EXPERIMENTS
Perennial warm-season grasses and corn with and without stover removal and cover crops. Start: 2012.
Perennial grass monocultures and polycultures. Experiment start: 2009.
Nitrogen, phosphorus, and potassium fertilization of switchgrass “Shawnee” Experiment start: 2010.
Location of the 3 experiments: UNL Agricultural Research Development Center (ARDC)

5. BIOFUELS NEED TO BE DONE RIGHT
Need to develop biofuels from systems that:
Reduce net emissions of GHG.
Maintain or increase soil C pools.
Reduce soil erosion
Do not compete with food crops
Improve wildlife habitat and diversity.

6. Aerially seeded cover crops before corn harvest
Strategies to ameliorate possible negative effects of residue removal effects on soil and environment
Aerially seeded cover crops before corn harvest

7. Improvement in Soil Properties, wildlife habitat, reduced soil erosion, water quality
Reduced bulk density, increased porosity, increased water retention, increased soil aggregate stability, and enhanced soil organic C aacumulation

8. What is the effect of dedicated bioenergy crops on soil properties when grown in marginally productive croplands?
Soil physical processes and properties.
Water erosion.
Wind erosion.
Soil carbon sequestration.
Others

9. EXPERIMENT I
Perennial warm-season grasses and corn with and without stover removal and cover crops. Start: 2012.
Ocassionally floded
2 acre whole plots
4 Feedstocks
Big bluestem – Bonanza/Goldmine
Switchgrass – Liberty
Low diversity mix (BB, IN, SO)
Corn (150 lbs N/acre)
3 replicates (1 acre subplots
2 N fertilizer rates (perennial grass)
N1 = 50 lbs N/acre, N2 = 100 lbs N/acre
No stover removal or 50% removal on ½ & add triticale cover crop (corn)
40% OF THE SITE IS MARGINALLY PRODUCTIVE DUE TO PONDING; 29% IS ERODED WITH 2-6% SLOPE
Eroded

10. Spring 2014 SOIL PROPERTIES MEASURED SOIL DEPTH RATIONALE Nutrients
0-7.5, , cm
Changes in soil fertility
Soil organic C
Changes in soil C
Particulate Organic Matter
Changes in SOM dynamics
Wet aggregate stability
Risks of water erosion
Dry aggregation
0-5 cm
Risks of wind erosion
Saturated hydraulic conductivity
Intact cores: 0-7.5, cm
Changes in water flow and retention
Moisture retention characteristics
Soil compactiblity
Changes in soil’s susceptibility to compaction

11. Water-stable soil aggregate stability
Soil compaction parameters

12. Where is the risk of water erosion higher?

13. Where is the risk of wind erosion higher?

14. WATER EROSION RISKS WIND EROSION RISKS
Perennials reduce water erosion risks
WATER EROSION RISKS
Residue removal increases water erosion risks
Perennials reduce wind erosion risks
WIND EROSION RISKS
Residue removal increases water erosion risks

18. EXPERIMENTS II: Perennial grass monocultures and polycultures
EXPERIMENTS II: Perennial grass monocultures and polycultures. Experiment start: 2009.
EXPERIMENTS III: Nitrogen, phosphorus, and potassium fertilization of switchgrass “Shawnee” Experiment start: 2010.
We studied changes in root biomass, soil organic C, total N, C:N ratio, water-stable aggregates, P, K, and bulk density after 5 yr in warm-season grass monocultures and polycultures and after 4 yr of inorganic fertilization of switchgrass.

19. Experiment II: Grass Monocultures and Polycultures
Experiment consisted of five high yielding perennial grass monocultures and polycultures.
Monocultures
1. Switchgrass “Shawnee”,
2. Switchgrass “Kanlow N1” 3. Miscanthus
Polycultures
Big bluestem (Goldmine) + indiangrass (Warrior) + switchgrass (Shawnee)
Big bluestem (Bonanza) + indiangrass (Scout) + switchgrass (Shawnee)

20. Experiment III: Fertilization and Harvest Date
Two factors: two switchgrass harvest dates (August and November) and NPK fertilizer rates
N (0, 60, and 120 kg ha-1): Main plots
P (0, 22, and 44 kg ha-1): Split plots
K (0, 11, and 22 kg ha-1): Split-split plots.
Four 100 cm long soil cores were sampled in spring 2014. 
The soil cores were sliced at: 0- 10, 10-20, 20-40, 40-60, and and cm depths.

21. Root biomass and soil C did not differ among perennial grass monocultures and polycultures after 4 yr.
Mean root biomass was 6.75 Mg/ha in the 0 to 10 cm depth and 2.5 Mg/ha in the 10 to 100 cm depth.
Inorganic (NPK) fertilization of switchgrass had no effect on root biomass, soil organic C, total soil N, water- stable soil aggregates, bulk density, and soil pH.
Significant differences may develop in the long term.

22. TAKE HOME MESSAGE
Dedicated energy crops such as perennial grasses maintain or improve soil properties and environmental quality compared with crop residue removal in marginally productive lands.
Monocultures and polycultures appear to have similar effects on root biomas, soil C, total, and other properties in the short term.
Inorganic fertilization of switchgrass may not affect soil properties in the short term.

23. OUR BIG THANKS TO THE NC-SUN GRANT CENTER FOR FUNDING THIS PROJECT.
ACKNOWLEDGEMENT
OUR BIG THANKS TO THE NC-SUN GRANT CENTER FOR FUNDING THIS PROJECT.
Field and lab team:
Leonard Kibet, postdoctoral researcher
Brian E. Maust, research technologist
Bulent Sezer (research scientis
Dallas M. Williams, undergraduate student
Carolyn Fox, undergraduate student
Liao Yi-nan. Northwest A&F Univ., China
Yang Ming. Northwest A&F Univ., China
Brian Maust, research technologist
Liao Yi-nan and Yang Ming. Northwest A&F Univ., China
From left to right
Rob Mitchell (Co-PI), Leonard Kibet, (post doc), Bulent Sezer (research scientist)

28. Publications/Presentations/Training:
ITEM
NUMBER
Abstracts
 4 (Meetings in USA and Germany).
Peer Reviewed Publications
 2 in preparation. The first one will be submitted on March 31, The second in July 30, 2015
Professional Presentations
4 presentations (Summer Ressearch Symposiums at UNL, Long Beach, CA, Nov. 2-5, and Liepzig, Germany, Nov 23-25)
Post-Docs Supported
1 postdoctoral researcher (Dr. Leonard Kibet): Two poster presentations. Prepared one manuscript almost ready for submission.
Undergraduate Students Supported
4 undergraduate students
Investigators Supported
 1 Research Technologist (Brian Maust)

29. Invited as keynote speaker to the “Biomass for energy – Lessons from the Bioenergy Boom” Conference, Leipzig, Germany, November, Organized by the Department of Bioenergy of the Helmholtz Centre for Environmental Research (UFZ) in cooperation with Deutsches Biomasseforschungszentrum (DBFZ)

30. SSSA Division: Soil & Water Management & Conservation
Oral Session Business Meeting--Soil & Water Management & Conservation Organizer: David R. Huggins
Oral Session Developing Sustainable Bioenergy Cropping Systems: I Organizer: Humberto Blanco
Oral Session Developing Sustainable Bioenergy Cropping Systems: II Organizer: Humberto Blanco
Poster Session Developing Sustainable Bioenergy Cropping Systems: III Organizer: Humberto Blanco

31. TIME FOR QUESTIONS