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Fluid Journal : Spring 2011
5 The Fluid Journal Spring 2011 may produce more corn stover than traditional 30-inch rows as well as greater below ground plant biomass. Biomass. Corn root biomass is substantially more effective at increasing soil organic matter and sequestering carbon (C) than corn stover. Most models estimating sustainable levels of stover removal also fail to include the substantial mass of C released to the soil in the form of root exudates. Despite frequently voiced concerns about removal of corn stover as an agent for reducing soil organic matter, we suggest (based on previous soil physical, chemical, and biological property analysis) that a percentage of corn stover is most judiciously used to promote the increasingly more efficient biofuel industry. A primary directive of the 2007 Energy Independence and Security Act is to promote ethanol production with a goal of 36 billion gallons by 2022, of which 21 billion gallons are to derive from cellulosic feedstock. When viewed from the landscape scale, we believe supporting the biofuel industry with harvested stover can be environmentally sustainable while also serving to help meet governmental directives regarding national energy independence and reducing dependence on fossil fuels. Organizing Ranking. By compiling research data from the past 20+ years at the Crop Physiology Laboratory (CPL) at the University of Illinois, we have ranked the factors that appear to have the greatest impact (both positive and negative) on corn yield. The seven factors are shown in Table 1. Prerequisites. In our quest for 300 bu/A corn, we determined an average bushel per acre value provided by each factor along with specific prerequisites such as drainage, fertility, and weed control. Included in the prerequisites were: • Proper soil pH and adequate levels of soil P and potassium (K) • Other soil fertility considerations such as sulfur (S) and micronutrients • Adequate weed, insect, and disease control Omission plot Based on our compiled research data, an omission plot experimental design was conceived to test five of the seven identified factors (N, other fertility, genetic traits, population, and growth regulators) for their individual and cumulative effects on corn yield: 1. No P or K versus 100 lbs P2O5 with S and Zn for balanced nutrition like MESZ (12-40-0-10[S] -- 1[Zn]) 2. 180 lbs UAN preplant versus 100 additional lbs of N sidedressed as a stabilized N source (like Super-U) 3. RR refuge hybrid versus insect- protection-traited hybrid like DKC 61-19 (both with soil insecticide at planting) 4. 32,000 plants/A versus 45,000 plants/A (both in 30-inch rows and twin rows in 2010) 5. No fungicide versus Headline or Quilt- Xcel (@ R1) Table 3 shows a comparison of high-tech versus standard practices ('Traditional') over two years and the resulting difference in corn yield. The yield enhancement from the use of the five high-yield factors was compared to the traditional system and the value of each individual factor was determined using the omission plot approach where each factor is either added (one at a time) to the traditional system or removed (one at a time) from the high-technology system. For instance, in the traditional package with a plant population of 32,000 plants per acre, the yield was 193 bu/A (second column, first row of Table 3); when the population was increased to 45,000 plants per acre while all other factors were maintained the same as the traditional package, yield decreased by 6 bu/A (to 187 bu/A; second column, row 5 of Table 3). In the high-tech package with all of the optimized inputs and plant population of 45,000 plants per acre, the measured yield was 245 bu/A (column 4, row 1 of Table 3). When the population was decreased to 32,000 plants per acre while all other factors were maintained the same as in the high-tech package, yield was reduced by 7 bu/A (to 238 bu/A; column 4, row 5 of Table 3). Based on data for 2008 and 2009, it was determined that population is an integral factor for high yield; however, we also recognized the need for plant density management at high populations to avoid interplant competition, which can decrease per- plant yield. We identified twin-row planting technology as a potential way to manage high plant populations that also allows for fertilizer application at planting near the seed. Table 1. Seven wonders of the corn yield world. Rank Factor Value Bu/A % 1 Weather 70+ 27 2 Nitrogen 70 26 3 Hybrid 50 19 4 Previous crop 25 10 5 Plant population 20 8 6 Tillage 15 6 7 Growth regulators 10 4 Total = 260 bu/A 100% Given key prerequisites Table 2. Greater nutrient removal with grain as a result of biotechnology traits. Nutrient Non RW Root worm Difference bu/A or lbs/A removed % Yield 179 205 15 N 110 126 14 P 17 21 24 K 26 31 19 S 8.9 10.4 17 Zn (oz) 2,2 2,8 27 Champaign, IL (2008) average of two hybrid pairs
Early Spring 2011