Ethanol Producer Magazine, ND
11-14-07
I-Farm Allows ‘In Silico’ Biomass Harvest
By Susanne Retka Schill
Farmers can now create virtual farming scenarios that include biomass harvests
using Iowa State University’s I-Farm, a free Web-based whole-farm decision
tool available at www.i-farmtools.org. The tool was recently expanded, so it can
be used to determine biomass harvest and its impact on erosion, soil fertility,
livestock operations, the farm’s energy and labor requirements, and a host of
other variables. “We call it ‘in-silico’—in the computer simulation,” says Robert
Anex, associate professor at Iowa State and associate director of the
university’s Office of Biorenewables.
Soils data from 36 states, compiled by the Natural Resource Conservation
Service, is now available to I-Farm users, according to Anex. The remaining
southeastern and southwestern states are being added as time permits. Iowans
also have aerial photographs available. Users zoom in on the maps of their
states and select the fields in their farms. The program then enters the soil type,
hill slopes and other field-specific details available from public databases.
Locations, feedstocks and capacities of all ethanol plants in the United States
have been added. Weather data, labor, energy, machine costs, custom farming
costs, crop production data and livestock production data are included in the
database-driven simulation model. The user can adjust the model to include the
user’s actual cost of cash rent, the number of acres owned, the actual tractors
used on the farm and more. The results pages show the farm’s nutrient needs,
nutrient credits from manure application, projected soil losses, crop and livestock
budgets, fuel use for equipment and crop drying, labor costs, government
payments, loan and investment figures, and annual income.
Anex says the I-Farm research team studied the effects of harvesting corn stover
on a fictional farm in Palo Alto County, the northwestern Iowa county where Poet
LLC is developing cellulosic ethanol processes at its corn-based plant in
Emmetsburg. The 1,000-acre farm mimicked the typical distribution of soil types
and slopes for the county. One scenario harvested no stover, one harvested
1,809 dry tons of stover per year, and the other harvested 3,077 dry tons per
year. The simulations found the farm that harvested the most stover also needed
the most fertilizer, had the most erosion and barely returned sustainable levels of
organic matter to the soil. That farm also recorded the highest net farm income
before taxes. Anex added that Poet’s current plans are to remove just the corn
cobs as biomass feedstock for the cellulosic ethanol plant, leaving the remaining
stover in the field.
Another simulation compared the single-pass method of corn stover harvest to
baling. Compared with grain harvest only, single-pass harvesting of corn stover
can increase biomass harvest 80 percent while increasing labor only 25 percent,
Anex says. With traditional baling techniques, 60 percent more labor is required,
and significantly more energy is consumed. To compensate for nutrient removal
from biomass harvest, nitrogen fertilizer applications should increase by 42
percent for 60 percent corn residue removal by baling, and increase 67 percent
for a 95 percent corn residue removal in a single-pass harvest, according to the IFarm simulation.
Anex reports that the availability of crop insurance and government programs
greatly reduces the economic risk of producing corn relative to a perennial grass
feedstock. On prime Iowa corn ground and without these programs, switchgrass
at $50 per dry ton would provide an expected return approximately equal to corn
at $2 per bushel. With these programs, the expected return of corn at $2 per
bushel is more than four times that of switchgrass at $50 per dry ton.
Anex adds that I-Farm developers plan to add 100 years of weather data to allow
simulations of weather risk, as well as algorithms to do carbon analysis. Farmers,
researchers and students are using the Web tool, as well as government
agencies such as the Iowa Department of Natural Resources, and extension and
conservation offices that help farmers develop conservation plans.