A.S. Henninger, M.L. Ruffo and F.E. Below 1
Ethanol production in the United States is rapidly increasing with approximately 135 ethanol production facilities in current operation, and with more than 75 plants under construction. Increasing demand for corn grain due to ethanol production has greatly increased the profitability of corn production, and growers who achieve preferred supplier status by delivering consistently high quality grain have additional marketing leverage. Competition among ethanol plants will increase as more plants come on line, and as the total ethanol production approaches the blend-wall, the plants that receive high quality local grain will be at a competitive advantage. Although it is clear that ethanol yield varies with hybrid and location (Haefele, 2004), it is unclear how other important crop management practices impact ethanol yield.
Even small changes in ethanol yield per bushel can have a big impact on profitability as a 0.1 gal/bu change in ethanol yield for a 48 million gallon per year plant is worth between $1-2 million (Tiffany and Eidman, 2003). Our previous FREC funded research (Ruffo et al., 2006) showed that crop management practices can have a large influence on grain quality, with high plant populations favoring high extractable starch and high N supply increasing grain protein. We know of no research about the effect of these management practices on ethanol yield that has been done.
New NIT based ethanol calibrations have been developed to screen for hybrids and conditions that alter ethanol yields (Haefele et al., 2007). Using this calibration, management factors can be more accurately evaluated for their influence on ethanol yield.
The objectives of this research were to determine how major corn management practices that farmer’s use to maximize grain yield also effect the quality of the grain for ethanol yield.
The experiment was conducted at three locations in Illinois to better understand how N fertilizer, plant population, and previous crop affect a hybrid’s productivity and ethanol yield.
An expanded version of the experiment was conducted at the Crop Sciences Research & Education Center in Champaign, IL to examine the effect of corn or soybean as the previous crop. At this site, an individual experimental unit consisted of one 17.5 foot long row, spaced 30 inches apart. The experiment was setup using a randomized complete block design in a split-split-split plot arrangement with previous crop (corn or soybean) as main plots, plant population as the subplots, N as the sub-subplots, and hybrids as the sub-sub-subplots. There were four replications of all treatments.
Similar experiments were conducted at the Northern Illinois Agronomy Research Center in Shabonna (DeKalb County), and at the J.F. Richards Land Laboratory, Demonstration and Research Farm in Joliet (Will County), except that previous crop was not included. Soybean was the previous crop at these two locations. Treatments were arranged in a split-split plot experimental design with hybrids as main plots, plant population as the subplots, and N as the sub-subplots. An individual experimental unit consisted of four 17.5 foot long rows, spaced 30 inches apart.
The same hybrids representing different and contrasting corn end-uses were planted at all locations. The corn hybrids were: DeKalb DKC57-79 RR/YGPL (107 RM) a yellow corn hybrid (YC); DeKalb DKC60-18 RR2/YGPL (110 RM) a high extractable starch hybrid (HES); DeKalb DKC63-74 YGPL (113 RM) a hard endosperm hybrid (HEC); and Asgrow RX756 (112 RM), a Nutridense hybrid (ND). At all sites, N rates were 0, 50, 100, 150, 200, and 250 lbs N per acre and plant populations were 28, 32, 36, and 40 thousand plants per acre.
The experiments were planted on April 24th and 25th in the three locations. Soil insecticide was applied at planting at all sites. The crop was over-seeded and thinned at the V5/V6 stage to the desired plant populations. The fertilizer N source was granular ammonium sulfate applied in a diffuse band down the center of each row at approximately the V3 growth stage, and incorporated with a field cultivator. Other established management practices conducive for high productivity were used according to local recommendations.
Grain yield estimates were obtained by hand in Champaign and by using a plot combine in the other locations. Grain samples were collected at harvest in each location and analyzed for ethanol yield using a Foss 1241 NIT grain analyzer. A Pioneer developed NIT calibration was used to determine the ethanol yield (Haefele et al., 2007).
Location and Hybrid
Large differences in grain yield were found among sites with DeKalb producing higher grain yield compared to Joliet and Champaign (Table 1). Yield differences were also observed among the hybrids with the HES and HEC hybrids yielding 13 bu/ac more than the YC hybrid and 33 bu/ac higher than the ND hybrid.
Ethanol yield varied 0.07 gal/bu between locations with grain produced in Champaign having the highest quality and grain from DeKalb the lowest (Table 2). As expected the HES hybrid exhibited the highest average ethanol yield which was 0.07 gal/bu higher than the next highest hybrid, and 0.10 gal/bu higher than the lowest. Among all sites and hybrids, the lowest ethanol yield was 2.81 gal/bu (DeKalb for ND) and the highest was 2.99 gal/bu (HES at Champaign) for a 6.4% range.
There was more genetic variability among the hybrids for grain yield (29% of the mean) than for ethanol yield (6% of the mean). The HES hybrid showed the least variation of ethanol yield between locations (0.05 gal/bu), and the ND hybrid exhibited the most variation (0.10 gal/bu). Conversely, the ND hybrid had the least variation in grain yield at 10 bu/ac, and the YC hybrid produced the greatest range among locations with a 43 bu/ac difference.
Nitrogen
Grain yield and ethanol yield had opposite responses to N fertilizer (Fig. 1). Grain yield increased an average of 55 bu/ac from application of the optimum N rate, while ethanol yield decreased by 0.07 gal/bu. Interestingly, the N rate which optimized grain yield was lower than the rate which minimized ethanol yield.
A negative relationship between N supply and ethanol yield was found for all hybrids at all locations (Fig. 2). The high ethanol yielding HES hybrid exhibited the smallest negative response to N (0.04 gal/bu) and the HEC hybrid the largest negative response (0.07 gal/bu) indicating that hybrids with the highest ethanol yield potential are less affected by N. Yield response to N and the optimum N rate also differed among hybrids (i.e. significant hybrid x nitrogen interaction) as the HEC hybrid had the largest response to N with a 112 bu/ac increase, while N increased yield of the ND hybrid by only 71 bu/ac.
Plant Population
Plant population influenced ethanol yield, but had a lesser effect on grain yield (Fig. 3). Grain yield was increased by increasing plant population at DeKalb and Joliet (by 13 bu/ac), but there was no response in yield from plant population at Champaign.
In contrast, ethanol yield increased 0.03 gal/bu as plant population increased from 28k to 36k plants per acre at Champaign, and 0.02 gal/bu in DeKalb and Jolliet (Fig. 4). Similar to N, plant population had a larger effect on low ethanol yielding hybrids than high ethanol yielding hybrids (data not shown).
Increasing the plant population reduced the negative effect of N fertilizer on ethanol yield (Fig. 5). Ethanol yield was highest with no applied N and low plant population, yet lowest with low population and high N. A plant population of 40k plants/acre was best in overcoming the negative effects of N.
Previous Crop
Grain yield was higher for the soybean-corn rotation than for the corn-corn rotation. The average grain yield for continuous corn was 194 bu/ac, whereas corn after soybean yielded 208 bu/ac. Opposite to the effect of N, corn-corn rotation increased ethanol yield for moderate N applications (Fig. 6), but higher applications of N resulted in no difference between corn or soybean as a previous crop.
The environment (soil and weather) had a more pronounced effect on grain yield than on ethanol yield. Hybrid selection is the largest factor affecting ethanol yield, but it should be carefully managed to maximize quality for grain and ethanol production. Grain yield is optimized with management practices that increase N availability. Soybean as the previous crop (14 bu/ac yield difference with respect to corn as previous crop), and 120 lb N/ac on average optimized grain yield (55 bu/ac average response to N). Increasing plant population had a minor effect on grain yield and only in DeKalb and Joliet.
Different ethanol yield potentials exist between hybrids (YC-2.85 gal/bu, HES-2.94 gal/bu). In order to achieve the highest ethanol yield a moderate N rate (100-120 lbs N/ac), high plant population (36k to 40k plants/ac), and corn as the previous crop should be used.
The combined effects of genetics and crop management can have an impact on ethanol yield. For example, a YC hybrid planted in DeKalb at 28k plants per acre with 250 lbs N/ac produced 0.26 gal/bu less ethanol compared to a HES hybrid grown at 40k plants per acre with 50 lbs N/ac. Such a difference would represent more than 3 million dollars for an average ethanol plant.
Figure 1. The effect of N rate on grain and ethanol yield in 2006.
Figure 3. The effect of plant population on grain yield and location on grain yield of corn in 2006.
Figure 4. The effect of plant population and location on ethanol yield of corn in 2006.
Figure 5. The effect of N rate and plant population on ethanol yield in 2006.
Figure 6. The effect of N rate and previous crop on ethanol yield in 2006.
1 A.S. Henninger is a Research Assistant, M. L. Ruffo is a Research Associate, and F.E. Below is a Professor, Dept. of Crop Sciences, University of Illinois, Urbana, IL
Haefele, D., F. Owens, K. O’Bryan, and D. Sevenich. 2004. Selection and optimization of corn hybrids for fuel ethanol production. In Proc. 59th Annual Corn and Sorghum Research Conference, Dec. 2004 (CD-ROM), Alexandria, VA.; American Seed Trade Association.
Haefele, D., D. Sevenich, D. Jones, J. Janni, S. Wright., 2007; Int. Sugar J. 109:154-162
Ruffo, M., A. Henninger, F. Below. 2006. Fertilizer and Management Inputs to Optimize End-Use Characteristics of Corn Hybrids. Illinois Fertilizer Conference Proceedings. pp. 85-93.
Tiffany, D., V. Eidman. 2003. Factors Associated with Success of Fuel Ethanol Producers. Staff Paper P03-7.