Bioenergy and Diversity from Sustainable Systems and Crops

Final Report for LNC08-293

Project Type: Research and Education
Funds awarded in 2008: $138,638.35
Projected End Date: 12/31/2011
Region: North Central
State: Iowa
Project Coordinator:
Sarah Carlson
Practical Farmers of Iowa
Dr. Rick Exner
Practical Farmers of iowa
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Project Information


This project has now completed the data collection, analysis and outreach activities to bring sustainable agriculture further into the public discussion of energy options by demonstrating a basic, practical cropping system that uses a fraction of the energy inputs as continuous corn and provides a net energy output that can be essentially the same while also supporting a diversity of farm enterprises.


The price of energy remains as a major expense for a farming operation and the cost of energy continues to be unpredictable. This project compared two practical Midwest cropping systems to explore the difference between energy use to grow and harvest crops, as well as to process those crops into biofuels and the resulting net biofuel energy and fossil energy ratio. Cropping systems with three or more crops use a fraction of the energy inputs as compared to continuous corn and provide a diversity of farm enterprises. Klepper et al. (1977) paired 14 Midwest organic farms with comparable farms not using organic practices, finding that the organic farms produced corn for roughly 36 percent the energy inputs per bushel used on the conventional farms. As noted, nitrogen fertilizer is the greatest single energy input in corn production. In the Klepper study, all farms whether organic or conventional kept livestock and applied manure. Thirty years later, these two types of farming have diverged. Many conventional row crop operations do not have access to manure, and up until the fall of 2012 N fertilizer rates have risen. The energy footprint of agriculture is an issue that SARE has always kept alive through research and demonstration projects. Practical Farmers of Iowa field days and workshops in 1992-1993 (LNC92-044) showed that farmer cooperators saved the energy equivalent of 12 gallons of diesel per acre by reducing nitrogen fertilizer an average of 50 lbs per acre. On-farm energy conservation and production continues to be a top priority for PFI members.

Project Objectives:

Short-term Outcomes: PFI’s media outreach, farmer field days, Dordt College field days and workshops and Annual Conference sessions has introduced the idea of energy savings through various practical on-farm methods to farmers, future farmers, and others including students. These stakeholders now are familiar with techniques and technologies that farmers and communities can use now and near-term to increase energy independence. Topics have included biodiesel, ethanol from sorghum, and switchgrass for municipal power, small wind chargers, and energy extraction technologies nearing the market. Our educational opportunities mentioned above have also aimed at helping them understand the connection between sustainable energy and sustainable agriculture so they may enter farming and other agriculture careers knowing how sustainable systems can support both farmers and global energy and environmental priorities.

Intermediate-term Outcomes: Farmers and others make informed choices that sustain the environment and are profitable in light of energy costs and their effects on agriculture commodity prices. As PFI's Energy program continues to develop from the opportunities available through this grant we have had an explosion of cooperators interested in a couple different types of on-farm energy projects. This project helped launch our Energy program. One group of farmers started with baseline data to measure and to understand how much current energy their farm is using. After baseline data was obtained, a second group has implemented changes in the farming practices to conserve energy. A third group is looking at energy generation on farm to reduce dependence on off-farm energy inputs. In addition PFI with Dordt College established side-by-side farming systems to compare the energy used and produced in the form of bio-fuels from two different farming systems. Several outreach activities have been accomplished from this study.

At the end of 2009 PFI changed one of the cooperators and began working with Dr. Craig Chase, a Farm and Ag Management Field Specialist at Iowa State University Extension to analyze the data from the ISU Marsden Farm Cropping Systems Study. Dr. Chase assessed labor requirements, input costs, and net returns for the conventional and diversified, low-external-input rotation systems used in the experiment. Data collected from the experiment plots concerning field operations, inputs, and yields, in combination with market prices and agricultural engineering and agricultural economics databases were used to complete the objective. Dr. Chase also developed energy budgets to assess the contrasting cropping systems using the established databases. To determine the effects of government subsidies, carbon payments, and “green payment” policies on economic performance of the different cropping systems, a profitability assessment with and without government program payments was conducted. Both existing subsidy programs and possible future programs (i.e., the results of new federal farm and climate legislation) were considered. The individual crop enterprise budgets developed has been adjusted to include or exclude government payments, aggregated into crop rotations, and compared. In addition, PFI staff devoted significant time to developing print publications, web updates, media placement and editorials on bioenergy and the need for diversity in cropping systems. That media outreach has focused on farmers as spokespeople in highlighting analyses farmers have done and changes they have made in their operations based on the research conducted in this grant.

Long-term Outcomes: The public and public policy view a sustainable energy future and sustainable agriculture as inseparable (See PFI's Research Report titled "Farm Energy Production and Use between Two Iowa Cropping Systems," attached under “Publications/Outreach”).


Click linked name(s) to expand/collapse or show everyone's info
  • Craig Chase
  • Chris Goedhart
  • Matt Liebman
  • Teresa Opheim


Materials and methods:

Dordt College established two farming system treatments in 2008: continuous corn (CC) versus a Gateway to Sustainability rotation (G2S) including corn, soybean, and oats with an underseeding of red clover. Dordt College documented all field operations for planting and harvesting, the inputs applied to each, and harvested yields (corrected for moisture content). Calculations are reported in the attached table(See Table 1: Field Operations).

PFI staff used the collected field data to create a fossil fuel flow chart of the energy used to grow the different cropping systems at Dordt College. Then PFI staff conducted a literature review and used published values to calculate the amount of energy needed to process the corn from both systems into ethanol and the soybeans from the G2S system into bio-diesel. The energy used to grow each of the crops was calculated from the diesel equivalents and organized into preharvest machinery, seed/inputs, and harvest machinery which were estimated from Iowa State University Extension publication PM709. Published values were also used to estimate the amount of renewable energy produced and the heating equivalent, as if the products were burned (See Table 2: Calculations).

Note: Yields were adjusted to accommodate the difference in rotation length. Since the G2S system is a three-year rotation, the corn, soybeans and oat/red clover crops is each only a third of the total area each year. In contrast, the continuous corn system is 100% of the total area each year. Therefore, 100% of the continuous-corn plot as was assigned as the effective-area, while only 33.3% of each G2S component was assigned as the effective-area. No bio-fuel product was estimated for the oat/red clover part of the rotation; therefore 33.3% of the G2S rotation was assigned a zero for the calculation. Two separate equations were used to summarize and report the final data results.

Equation 1. Energy Efficiency = Total Biofuel Energy Output / Total Energy Input
where: Total Energy Input = Farm Energy Cost of Production + Biofuel Processing Energy.
The Energy Efficiency value is a dimensionless ratio of the amount of energy returned as either ethanol or bio-diesel for each unit of energy put into the system, specifically in the processing, planting and harvesting of the crop.

Equation 2. Land Efficiency = Net Biofuel Energy Output – Farm Energy Cost of Production
where: Net Biofuel Energy Output = Total Biofuel Energy Output – Biofuel Processing Energy
The Land Efficiency value is reported in mega-BTUs/Acre. This value is the NET energy produced per acre.
Energy Efficiency is a ratio of the output energy to the input energy, while the Land Efficiency is the netted amount of energy per area of land. To understand how efficient the cropping systems were in their production of energy per acre we used both equations to ultimately determine which systems were more efficient (See Table 3: Energy Summary).

Data Analysis

Statistics were analyzed using JMP Pro 10 (SAS Institute Inc., Cary, NC) and yield comparisons employ least squares means for accuracy. Comparisons of means were analyzed using the Tukey Honestly Significant Difference. Statistical significance is determined at a ? =0.05 level (See Table 4: Stats).

Research results and discussion:


Based on the Energy Efficiency equation the G2S system in 2009 (1.77 M-BTU/M-BTU) and 2011 (1.76 M-BTU/M-BTU) were significantly more efficient than the G2S in 2010 (1.72 M-BTU/M-BTU) (Table 1). They were more than CC in 2009 (1.29M-BTU/M-BTU), 2010 (1.32 M-BTU/M-BTU) and 2011 (1.28 M-BTU/M-BTU). The G2S system yearly yielded 36%, 30% and 38% more energy respectively for every fossil fuel BTU expended to plant, harvest and process the crops as compared to the CC system. However it is important to consider the total amount of energy that the different farming systems produced per acre. Conversely, based on the Land Efficiency equation the CC treatment yielded significantly more energy per acre (9.49 M-BTUs/A) in 2010 than any other treatment in any other year. The CC treatment in 2009 and the G2S in 2010 yielded the same statistically at 7.92 MBTUs/A and 7.32 MBTUs/A, respectively. These treatments were similar to both farming system treatments in 2011 (7.10MBTUs/A and 7.07MBTUs/A). The G2S treatment in 2009 yielded the least amount of total energy/A at 6.02 MBTUs/A. In two years out of three the CC and G2S farming systems produced similar amounts of total energy/acre. The G2S farming system is not only more efficient in the amount of energy it takes to produce the resulting energy commodity but also total production of energy/A was similar to the CC farming system two out of three years.

--Heat Energy

The heat energy equivalent was also calculated to demonstrate the amount of energy produced if the corn and soybean grains harvested from the cropground were burned instead of processing them into biofuel. The magnitude of energy produced is much greater than when turning the crops into a liquid biofuel. Based on the Energy Efficiency equation in 2010 the G2S yielded the greatest amount of heat energy for every M-BTU used in the system (96.5 M-BTU/M-BTU) (Table 2). The G2S system in 2011 (89.6 M-BTU/M-BTU) and 2009 (68.0 M-BTU/M-BTU) were statistically different and less than 2010 but significantly greater than all years in the CC system. All years were statistically similar for the CC system and averaged 15.2 M-BTU/M-BTU. Comparing the yearly averages of the two systems the G2S yielded 5.5 times more heat energy for every M-BTU expended to plant and harvest the crops as the CC system. However based on the Land Efficiency equation the CC system in 2010 (64.9 M-BTU/A) yielded significantly more than the CC 2009 (56.8 M-BTU/A) and CC 2011 (52.6 M-BTU/A) treatments. The G2S system in 2010 and 2011 yielded statistically more heat energy than in 2009. The annual average of the CC system yielded 1.3 times more heat energy per acre than the G2S.


When considering both the Energy and Land Efficiency calculations together, the G2S requires less energy input (i.e., BTUs per acre) to convert energy from a crop to a biofuel. The G2S system is more efficient and for biofuel production can achieve similar yields per acre as the CC system. Additionally even though the CC system produces more heat energy per acre it requires 5.5 times more energy to create heat energy. In order to draw an appropriate conclusion, the analysis must include the economics and the CO2 emissions produced by the two different cropping systems. This “expanded analysis” would be an excellent opportunity for future funding.


To achieve the short-term and intermediate-term goals PFI has a long history of our members hosting field days to start the conversation about on-farm research interests including energy conservation and also the transfer of knowledge between farmers who are actively making changes.

Field Days and Workshops

An important component of the project is the demonstration of practices and farm-scale energy technologies that producers can use to increase their energy independence or reduce the farm's energy footprint. To that end, the following farm workshops, field days and conference sessions were held since late 2008.

1) On August 30, 2008, Wisconsin biodiesel expert Kim Odden demonstrated fuel production directly from oilseeds and described the economics at a northeast Iowa field day organized by PFI members Gary Laydon and Pat Mennenga. 20 farmers attended. Oilseeds are an inevitable part of on-farm biodiesel, since the limited supply of fry oil has been largely spoken for. The relative merits of the major oilseed crops have changed drastically in the six months since the workshop due to falling energy costs and the declining economy. A handout with pictures is attached in this report or available online at:

2) On September 17, 2008, 55 farmers and Dordt College students gathered to see Dordt College engineer Ethan Brue demonstrate a farm-scale distillation column and sweet sorghum that could be a feedstock for ethanol. Ethanol from sorghum, unlike ethanol from grain, requires no fermentation stage; additionally, the great weight and bulk of the sorghum stalks make on-farm processing of the crop the natural choice. Small-scale distillation is one of the critical pieces of the puzzle to make sorghum energy practical on the farm.

3) In south-central Iowa, John and Jean Sellers hosted a field day on September 27, 2008 on cellulosic energy from switchgrass. 14 farmers attended this event. John was a founder of the Chariton Valley Switchgrass Biomass Project. In attendance at the field day were agency representatives who discussed how to coordinate to make it easier for farmers to transition cool-season CRP plantings to warm-season energy crops like switchgrass.

4) 38 farmers attended a field day to demonstrated three ways to use heat and pressure to yield a variety of fuels: pyrolysis, gasification and supercritical fluid extraction was held on July 14, 2009 at Biomass Energy Conversion Center in Nevada, IA.

5) 40 Dordt College students and farmers attended a field day on September 9, 2009 where results from the first year of a 3-year comparison of 2 crop rotations: continuous corn and 3-years corn-soybean-oat/Clover were discussed. Enterprise opportunities with each rotation were also discussed.

6) 19 farmers attended the workshop and the tour of facility at Yoderville Biodiesel Collective on August 28, 2010. Attendees watched equipment in action, and visited with collective members to discuss about production, economics, politics, and the prospects for biodiesel from waste oil and from oilseeds.

7) 32 farmers and Dordt college students attend a field day on September 1, 2010. Results from the first two years of a 3-year rotation of 2 crop rotations: continuous corn and 3-years
corn, soybean, oat/clover were presented, followed by the discussions on how the results have been used by college students to educate high school students in concepts of sustainability, net energy, and factors affecting cropping decisions.

8) 24 farmers attended a field day at Ellsworth Community College Ag & Renewable Energy Center on September 10, 2010. Student Interns for Ag and Energy and Dr Chris Goedhart, chair of the Department of Agriculture at Dordt College presented their crop rotation study along with several other presenters.

9) 90 Dordt College students and farmers attended an evening field day on August 31, 2011 focused on results from several projects Dordt College is conducting on their college’s farm. Chris Goedhart along with Dordt College students and Rich Schuler, PFI on-farm energy consultant, presented about the Gateway to Sustainability SARE project. See a picture of the Cropping Systems plots here: Read more here about the general topics discussed at the field day:

10)45 farmers attended a field day at Francis Thicke's farm on August 27, 2011 to hear about several different on-farm energy projects that Francis and other farmers were testing on their farms. Read more here:

11)140 farmers attended a field day at Harn Soper's farm on October 21, 2011. Rich Schuler is working with the Soper’s to design a composting system that creates heat and gas to keep the greenhouse heated without using off-farm energy. The greenhouse location is pretty far from an electrical line so that allows the farm to be creative in how they will “fuel” the system because running a line to the building will be expensive. Read more here:

12)40 farmers attended a field day at the Marsden farm study at the Iowa State University Agronomy Farm on September 13, 2011 to learn more about the economic and energetic comparisons of different cropping systems. Read more here:

13)35 farmers attended a PFI Annual Conference session on January 13, 2012, which was focused on the results of the Marsden Farm study that is part of this SARE grant as well. PowerPoint presentations of the presenters can be found at

14) Rich Schuler gave a presentation titled, “On-farm Energy Use: record-keeping tips” at our annual Cooperators’ Meeting on February 7, 2012, where he discussed the methods used to conduct on-farm energy record-keeping projects.

15) 70 farmers attended a field day at Harn Soper’s farm on September 27, 2012. Rich Schuler gave a PowerPoint presentation on the energy use of three coolers on the farm. Attendees also toured these coolers.

On-farm Research Projects

Francis Blake----Farm Metered Energy Analysis - Getting Baseline Data
Craig and LaVon Griffieon----Farm Metered Energy Analysis - Getting Baseline Data
Susan Jutz----Farm Metered Energy Analysis - Getting Baseline Data
Mark Tjelmeland----Farm Metered Energy Analysis - Getting Baseline Data
Tom & Irene Frantzen----Groundtruthing Changes - Solar thermal & gasification (corn cobs)
Eric and Ann Franzenburg----Groundtruthing Changes - CoolBot based Walk-In Cooler & Biomass burning (shelled corn)
Liz Garst----Groundtruthing Changes - Gasification (wood)
Jason Gomes----Groundtruthing Changes - Underground storage & curing structure
Tim Landgraf----Groundtruthing Changes - Solar PV, solar thermal and cooler efficiency
Joe Lynch----Groundtruthing Changes - Wind energy
Harn Soper----Groundtruthing Changes - CoolBot based Drive-In Cooler
Sean Skeehan----Groundtruthing Changes - CoolBot based Walk-In Cooler
Bill Pardee----Groundtruthing Changes - Solar PV
Mark Rundquist----Groundtruthing Changes - Conservation & Wind Energy
Harn Soper----Groundtruthing Changes - CoolBot based Drive-In Cooler
Francis Thicke----Groundtruthing Changes - Solar thermal
Dick Thompson----Groundtruthing Changes - Window insulation
Mike Salama----Groundtruthing Changes - Biomass burning (wood chips)
Frank Santana----Groundtruthing Changes - Wind turbine

Research conclusions:

Impact on students

In spring of 2011, student posters on energetics were viewed by students who came to Dordt campus in conjunction with the Dordt College Ag Day. Because they were not able to determine which students would come to campus (an open invitation and judging contest), no pre- or post test data could be collected.

During each of the past three years, primarily freshmen students both in introductory agriculture, food science, and environmental sciences courses received presentations on agricultural sustainability, and cropping system energetics. The yearly average of students was 100 students in environmental studies, 24 in a foods course, and 53 students in an introduction to plant sciences course. In years one and two, students in the plant sciences course completed an intensive 3-week laboratory exercise which required groups of 3 to 4 students to prepare a 10-page formal laboratory report along with graphs and figures illustrating concepts of sustainability, environmental impacts, and energetics of cropping systems. Students were involved in small plot harvests of corn grain and clover biomass, and soil sampling for post-harvest nitrate soil concentrations. They also received data of in-season spring soil nitrate concentrations and leaf chlorophyll concentrations. In year 3 with a couple of previous years yield data, groups of students prepared posters and gave oral presentations about energetics and net energy of the two cropping systems. While the lab reports and poster projects were perceived as quite difficult, many students reported an appreciation for and better understanding of the concept of net energy and overall energetics of cropping systems. However no comparison gauging increased knowledge or attitudes was conducted.

Seminars by Dordt College professors

Verburg – Presentation of SARE grant research in summer 2009 to Wednesday seminar series
Approximately 20 students and faculty.

Leutchens – presentation in fall 2010 at Kuiper’s scholars (Honors) colloquium to approximately 25 students and advisors on biofuels and sustainability.

Goedhart – presentation in September 2009 to the Iowa Farm Business Associates annual meeting held at Dordt College. The presentation: Bioenergy and Diversity from Sustainable Systems and Crops was presented to 25 associates.

Goedhart – Presentation in July 2010 at the Wednesday Summer Seminar Series. The presentation, Biofuels and Sustainability: Puffery or Reality?, was given to 40 faculty, staff, and students.

Goedhart – Presentation in September 2010 at the Ellsworth Community College Field Day. The presentation, Biofuels and Sustainability: Puffery or Reality?, was given to 45 students and community farm supporters.

Goedhart – Invitation to present a session in September/October 2012 at Wilmington College in Wilmington OH to agriculture students on Bioenergy and Sustainability.

Goedhart – in progress a paper based on the July 2010 presentation to be published in Pro Rege.

Stout and Bierma constructed a PowerPoint presentation, a testing instrument, and an interactive Excel worksheet for use in area high school classrooms beginning in the spring of 2010. This presentation and the interactive spreadsheet allowed students to determine the effects on net energy as they compared a continuous corn monocrop with its required nitrogen inputs with a rotational system which included soybeans and small grains underseeded with clover.

The following questions were used to gauge student attitudes about sustainability and energetics.

1. I believe that practicing sustainable agriculture is:
Very important 1 2 3 4 5 Not important
2. I understand what is meant by sustainable agriculture:
A clear understanding 1 2 3 4 5 A poor understanding
3. I understand how a cropping system’s energetics are evaluated
A clear understanding 1 2 3 4 5 A poor understanding
4. I believe that learning about energy production and use in agriculture is:
Very important 1 2 3 4 5 Not important
Using a paired comparison of the pooled data, a t-test of students’ initial and final reported attitudes or understanding showed a statistically significant increase in understanding or belief in the importance of learning about energy production and use in agriculture in three of the above questions.

Students were also tested on eleven knowledge-based elements of the presentation, but in testing students, they only showed statistically significant improvement in one of eleven questions. The students attributed this minimal improvement to the short time period (typically 45 minutes) provided for the presentation and for work on an Excel spreadsheet.

Economic Analysis

“Energy and Economic Returns by Crop Rotation,” published in Ag Decision Maker (the complete document is attached under “Publications/Outreach”) discusses economic returns for the three rotations, in addition to their energy use. When looking at economic profitability, the three and four year rotations demonstrated the ability to compete with the two-year rotation, resulting from the increase in yields while having dramatically lower input costs in field operations, fertilizer and pesticides. Specifically, in this study, the three-year rotation showed the highest economic returns as it increased yield while decreasing input costs.

Farmer Adoption

Field day attendants to Dordt College were asked to fill out a survey. PFI evaluates the quality of the content presented at the field day, how useful it is to the attendants and what changes to their farming systems they will make or have made due to attending this or other PFI events.

All of the survey respondents who attended the annual Dordt College field day on September 16, 2009, answered either very useful or useful to the question, “How useful was the information presented?” They also responded they may change their farming practices as a result of the information received at this field day.

Almost 80% of the survey respondents, who attended the field day on September 1, 2010 at Dordt College, answered in the evaluation that the information presented was extremely useful or useful, with one of the respondents commenting “I was surprised with the amount of knowledge I gained from attending this field day.” 75% of the respondents also indicated that they are or they may be considering changing some farming practices as a result of the information received at this field day.

In the 2012 PFI Membership Survey several farmer members indicated the importance of crop rotation studies in response to the question: “How has your participation in PFI impacted your farm's performance?” They mentioned how information about our research and outreach on crop rotations has helped improve their farms practices and performance.
We determined that we have already gained enough feedback to determine that energy was a top priority of our membership, as well as the area of research interests from our membership survey results. Our organization responded to the enthusiasm of farmers in the Cooperators Program wanting to do more with Sustainable Ag and Energy Production and as a result we have built a new program to meet their needs, and added a number of new energy related cooperators projects in the years 2011 and 2012 as listed under “Milestones/Accomplishments” above.

The findings from the two University research projects demonstrated for a three-year crop rotation reduced energy use and increased economic returns in the Marsden Farm study and increased energy efficiency for energy produced in the Dordt Study. These results have helped us leverage new funding sources for a new research project, which is moving this study from the research farm to real, working farms. Farmers need to test new ideas on their farms, and see how this three-year rotation could be most practically and easily added to their farming business. Our cooperator farmers will assess the three-year rotation’s economic and agronomic performance, and the findings based on this SARE project will be an important guiding literature as we continue this new research.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

PFI Research Report
Carlson, Sarah and Rich Schuler. 2012. Farm Energy Production and Use Between Two Iowa Cropping Systems.

Iowa State University Extension and Outreach Publication (Ag Decision Maker)
Johanns, Ann and Craig Chase. 2012. Energy and Economic Returns by Crop Rotation. File A1-90.

PFI Newsletter Articles
1. Vol. 26, No.2, Spring 2011, PFI member refuses to be held hostage by oil prices (Patrick Burke)
2. Vol. 26, No.4, Fall 2011, Bioenergy and diversity from sustainable systems and crops (Rich Schuler)
3. Vol 27, No.1, Winter 2012, Profit more by using less, without sacrificing yield (Sarah Carlson)
4. Vol. 27, No.1, Winter 2012, Solar Photo Voltaic pays off for PFI members (Rich Schuler)

Project Outcomes


Areas needing additional study

Additional areas of funding could include the Economics and the CO2 emissions comparisons between both treatments.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.