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© 2008 Plant Management Network. Climate Change: Has Climate Become More or Less Favorable for Growing Corn Over the Past Century? E. C. A. Runge, Professor and Billie Turner Chair in Production Agronomy (Emeritus), Soil & Crop Sciences Department, Texas A&M University, College Station 77843-2474; and John F. Benci, Consultant, 382 Moore Road, West St. Paul, Manitoba, Canada R4A 7A2 Corresponding author: E. C. A. Runge. e-runge@tamu.edu Runge, E. C. A., and Benci, J. F. 2008. Climate change: Has climate become more or less favorable for growing corn over the past century? Online. Crop Management doi:10.1094/CM-2008-0609-02-RS. Abstract Corn yield and production varies from year to year depending on the favorableness of weather during the growing season. Weather records were used to simulate corn yields from 1922-2002 for 11 Corn-Belt land grant university locations, for four different planting dates, and for three different amounts of plant-available stored soil moisture at or near planting time. Weather data were selected to have corn tassel on 24 June, 8 July, 22 July, and 5 August. Results from this study were combined with a previous study and corn yields simulated for Urbana, IL (1903-2002); Lafayette, IN (1901-2002); Ames, IA (1901-2002); Columbia-Fulton, MO (1901-2002); and Lincoln, NE (1922-2002). Corn yields increase for all sites for the combined study indicating that rainfall and maximum air temperatures have become more favorable for growing corn over the past century. This is the first study reporting yield data for the past century with a fixed technology for growing during the entire period studied. Data for sites not presented are available by request from the corresponding author, E. C. A. Runge. Introduction Corn yields were simulated using the water balance model developed earlier (5). The model was derived from plot data from the 1969, 1970, and 1971 growing seasons from four sites along a 200-mile north-south transect in Illinois. Farmer’s fields were selected where soil variation caused large differences in plant-available stored soil moisture and corn yield within small areas (4). The importance of plant-available stored soil moisture is well recognized for its importance in determining corn yield (4,6). All plots at a location were within a couple hundred feet of each other [plots were located within no more than 2 acres within larger fields (4)] so rainfall and temperature data collected on site represented the location. Rainfall and temperature differences occurred between years at each site and between sites within and between years (4,5). Plant-available stored soil moisture differences are due to variation in loess thickness overlying high bulk density glacial till (LaSalle and Champaign counties), and due to variation in depth to horizons high in Na+ concentrations (Fayette Co., two locations). Both soil conditions restrict rooting depth and limit the amount of water available to growing corn. The model used here explained 81% (R˛) of the corn yield variation for these four sites for these three years [see (4,5) for additional detail] and uses readily available inputs in contrast to other models (1,2). The model was used previously to simulate corn yield and production under variable climatic conditions for Urbana, IL; Lafayette, IN; Ames, IA; Manhattan, KS; Columbia, MO; and Lincoln, NE (7). Model sensitivity and applicability were further tested in this study to include land-grant university’s located in Illinois, Iowa, Indiana, Kansas, Michigan, Minnesota, Missouri, Nebraska, Ohio, South Dakota, and Wisconsin and to use weather available through 2002. Real time corn yield forecasting for these 11 states in the Corn Belt are reported separately (9).
Concerns and Limitations One concern is how technology used to produce corn in 1969-1971 compares to technology used to produce corn today. In the prior study (7) experimental technology (4,5) was related to Corn-Belt technology (state average corn yields available from www.nass.usda.gov) for the years 1968-1972. State average corn yields were compared to model derived corn yields for these same years for a mid-July tassel date and for 10 inches of plant-available stored soil moisture using Urbana, IL; Lafayette, IN; Ames, IA; Manhattan, KS; Columbia, MO; and Lincoln, NE, yield simulations to represent the state (7). Corn-belt technology for these 5 years ranged from 54.2 to 78.3% (average was 65.2%) of the experimental technology for these six sites (4,5,7). The average technology was calculated by dividing NASS-USDA state average corn yields by model derived corn yields for each location. Technology used in growing corn today produces higher corn yields than when the model was derived (5,9). Much of the increase in corn yield is due to higher plant population (3). DeKalb’s XL 45 and XL 45a hybrids were used (4,5) and these hybrids were among the first widely adapted high population single cross hybrids grown. Plant population in the study (4,5) was 21,425 plants per acre and ranged from 18,225 to 25,717. The average plant population for Illinois, Iowa, and Indiana in 1969-1971 was 17,800 while it was 27,400 plants per acre for 2004-2006 (Ty Kalaus, Field Crop Section, NASS-USDA, personal communication). Fulton, MO, was used instead of or combined with Columbia, MO, for this study (1922-2002 or 1901-2002). Another major question is whether or not model simulated yields (5) can be used to represent growing conditions over the entire Corn Belt. Above-average maximum temperature decreases yields, above average rainfall (generally) increases yields, and high amounts of plant-available stored soil moisture increases yield and decreases year-to-year variation (4). Our results are reasonable, agree with experience, and also mimic NASS-USDA reported yields, suggesting that model results are applicable to the entire Corn Belt (9). Assumptions in Using the Model • All other inputs/factors determining corn yield are non-limiting and are the same for all years studied (i.e., hybrid used, fertilizer, weed control, tillage technology, etc., are constant for the period where yields are simulated). • Corn responds to moisture stress today the same as it did when the model was developed (4,5,6). This may not be valid since many of today’s hybrids may be more drought tolerant than were DeKalb’s XL 45 and XL 45a. [Results for 2005 (9) indicate that today’ hybrids are more drought tolerant than were DeKalb’s XL 45 and 45a.] • Absolute yields are fixed to technology when the model was developed (1969-1971), consequently yields reported here should be increased some 25 to 35% for technology used in today’s corn growing areas of the Corn Belt, particularly due to increased plant populations (3). Data Presented Selected locations are used to demonstrate results found in the study. Results give what expected corn yield would be for each location for any previous year if that weather reoccurred and if corn was grown as it was from 1969-1971 (5). Results are reported in bu/acre and are given for Urbana, IL, in Figure 1; Madison, WI, in Figure 2; and Brookings, SD, in Figure 3 for corn that would tassel on 24 June, 8 July, 22 July, and 5 August. The 24 June results presented for Madison and Brookings may not be possible because of frost early in the growing season. Results from the previous study (7) are combined with results from this study for mid-July tassel date and for 10 inches of PASSM for Urbana, IL, in Figure 4; for Lafayette, IN, in Figure 5; for Ames, IA, in Figure 6; for Columbia-Fulton, MO, in Figure 7; and for Lincoln, NE, in Figure 8. Yields reported have not been adjusted for any improvement in technology that has occurred since 1969-1971. Results in a subsequent paper (9) suggest that model simulations capture the upward bias in yield that occurs when weather is favorable [i.e., 2004 yields (9)]. However the model did not seem to capture all the increase in corn yield when moisture was more limiting [i.e., 2005 corn yields (9)]. If that is true, then current hybrids are more drought tolerant than were DeKalb’s XL 45 and 45a.
Yields: Urbana, IL Results are for weather that occurred from 1922-2002 (Fig. 1). Results for Lafayette, IN; Ames, IA; Lincoln, NE; Columbia/Fulton, MO; and Wooster, OH, are similar to Urbana, IL results. A positive trend line occurs for most tassel dates and plant-available stored soil moisture levels at planting. Yields for Ames, IA; Lafayette, IN; and Wooster, OH, were similar or slightly higher compared to Urbana, while yields for Fulton, MO, were lower and more variable. Yields for Manhattan, KS, and Lincoln, NE, were much lower and more variable than Fulton/Columbia, MO, yields. Yields for Wooster, OH, had less year to year variation than did Urbana, IL. Yields for the 24 June tassel date were generally higher for good soils (plant-available stored soil moisture at planting of 10 inches) but were lower and more variable for intermediate and poor soils (plant available stored soil moisture at planting of 7 and 4 inches, respectively) then were yields for 8 July, 22 July, and 5 August tasssling dates. Lincoln, NE, and Manhattan, KS, had years with zero or very low yields when plant-available stored soil moisture at planting was 4 inches and even some years when it was 7 inches. The western Corn Belt often has insufficient rainfall to bring soil moisture content up to field capacity by planting time. Year-to-year corn yield variation was greatest with early tassel date (24 June) and least with 5 August tassel date. Year-to-year yield variation decreased as the tassel date moves from 24 June to 5 August and as plant-available stored soil moisture at planting goes from 4 to 10 inches. Model derived yields were lower for 8 July and 22 July than for 24 June and 5 August tassel dates. Conclusions: • Results for Urbana are similar to Ames, IA; Lafayette, IN; Lincoln, NE; Columbia/Fulton, MO; and Wooster, OH. • Yields increased from 1922-2002 due to improved weather for growing corn. • Pollination early in the growing season produces highest corn yields but with more year year-to-year variation than later dates. • Year-to-year yield variation is greatest for 4 inches, intermediate for 7, and least for 10 inches of plant-available stored soil moisture at planting. • Year-to-year yield variation is greatest for early pollination and least for late pollination. Yields: Madison, WI Results reported are for weather that occurred from 1922-2002 (Fig. 2). Results for East Lansing, MI, and Minneapolis, MN, are similar to results reported for Madison, WI. Yields levels (bu/acre) for all three locations were similar and somewhat higher than for Urbana, IL, for the same plant-available stored soil moisture and tassel dates. Trend lines were consistent between all three sites and had nearly zero slope for all planting dates and for all plant-available stored soil moisture levels. Year-to-year yield variation is less for these northern locations then for Urbana, IL. Yield levels for soils with 4 inches of plant-available stored soil moisture at planting are less variable and higher than they are for Urbana. Yields for soils with 7 inches of plant-available stored soil moisture at planting at these more northern locations are similar to yields for soils with 10 inches of plant available stored soil moisture at planting at Urbana. Soils with 4 inches of plant-available stored soil moisture at planting are much higher than for Urbana. For these northern locations soil areas supplying 10 inches of plant available stored soil moisture at planting occur less frequently than for Illinois, Iowa, and Indiana. Year-to-year yield variation decreased as tassel dates moved from 24 June, to 8 July, to 22 July, to 5 August and as plant-available stored soil moisture at planting went from 4 to 10 inches. Conclusions: • Results for Madison are similar to East Lansing, MI; and Minneapolis, MN. • No trend in yields occurred due to weather for the period studied (Minnesota had a slight positive trend, for soils storing 4 inches of plant-available stored soil moisture). • Pollination early in the growing season produces highest corn yields but with more year-to-year variation than later dates. • Less year-to-year yield variation occurred for Madison than for Urbana, IL, and other more southerly locations. • Low plant-available stored soil moisture soils at planting (4 inches) have higher and less variable yields than for locations further south. • Yield variation is greatest for 4 inches, intermediate for 7 inches, and least for 10 inches of plant-available stored soil moisture at planting. Brookings, SD, Yields Results reported are for weather that occurred for years 1922-2002 (Fig. 3). Results for Brookings are presented separately since the Brookings location had the largest increase in corn yield due to weather for all 11 locations studied. In general, western Corn-Belt locations (South Dakota and Nebraska) have more positive trend lines than do more eastern Corn-Belt locations. Year-to-year yield variation is more for Brookings than for Minnesota, Wisconsin, Iowa, Illinois, Indiana, and Ohio but less than for Missouri, Kansas, and Nebraska. Year-to-year yield variation decreases as the tassel date moves from 24 June to 5 August and from 4 to 10 inches of plant-available stored soil moisture at planting. Kansas weather during this interval has not improved according to model results. Conclusions: • Results for Brookings have the highest positive trend in corn yield for weather from 1922-2002 for all locations studied. • Pollination early in the growing season produces highest corn yields but with more year-to-year variation. • Year-to-year yield variation is larger for all plant available stored soil moisture levels at planting than for other corn belt locations, except Fulton, MO; Lincoln, NE; and Manhattan, KS; and is similar for all planting dates. • Year-to-year yield variation is greatest for 4 inches, intermediate for 7 inches, and least for 10 inches of plant-available stored soil moisture at planting. Comparing Results for Present and Previous Study Results from the previous and present study were combined and are given for Urbana, IL (Fig. 4 for 1903-2002); Lafayette, IN (Fig. 5 for 1901-2002); Ames, IA (Fig. 6 for 1901-2002); Columbia/Fulton, MO (Fig. 7 for 1901-2002); and Lincoln, NE (Fig. 8 for 1922-2002). The previous study (7) went from the beginning of the weather record through 1972 and was for a 18 July tassel date. The present study went from 1922-2002 and was for a 22 July tassel date. Urbana, IL; Lafayette, IN; and Columbia, MO, had a flat or no trend in corn yields through 1972 but the trend line became positive when extended to 2002. Ames, IA, has the same positive trend line for both 1901-1972 as for 1901-2002. Lincoln, NE, had a less positive trend line for the period 1922-2002 than it had for the period 1922-1972. The impact of the large number of yields below the trend line from 1932-1942 for Lincoln for 1922-2002 is reduced as the length of the study expanded from 1922-1972 to 1922-2002. This 11 year period of low yields is also apparent at other Corn-Belt locations. All five locations (Illinois, Indiana, Iowa, Missouri, and Nebraska) have improvements in weather leading to more favorable corn yields today than they did earlier. Conclusions Model derived yields give a good indication of what corn yields would be today if weather that occurred during previous years reoccurred. Yield levels reported are based on 1969-1971 technology and should be increased some 25 to 35% to mimic today’s corn yields. Weather is more favorable for growing corn today than it was earlier for Illinois, Indiana, Iowa, Missouri, Nebraska, Ohio, and South Dakota. Weather for growing corn improved the most for South Dakota than for any other location. Weather for growing corn in Michigan, Minnesota, and Wisconsin is the same today as it was earlier. Weather affected corn yields for all 11 locations as follows: 24 June or 8 July, the earliest effective tassel dates for a location, always produced the largest yield; the lowest yields occurred with the 22 July tassel date; and 5 August yields were similar to 22 July yields but were almost always somewhat larger. Soil quality, as measured by plant-available stored soil moisture at planting (4, 7, and 10 inches), impacts corn yield the most for the southern (Illinois, Indiana, Iowa, and Missouri) and western (Kansas, Nebraska, and South Dakota) Corn-Belt locations and had the least impact on corn yields for northern (Wisconsin, Michigan, and Minnesota) and eastern (Ohio) Corn-Belt locations. Literature Cited 1. Anapalli, S. S., Ma, L., Nielsen, D. C., Vigil, M. F., and Ahuja, L. R. 2005. Simulating planting date effects on corn production using RZWQM and DERES-maize models. Agron. J. 97:58-71. 2. Baez-Gonzalez, A. D., Kiniry, J. R., Maas, S. J., Tiscareno, M. L., Macias, C. J., Mendoza, J. L., Richardson, C. W., Salinas, G. J., and Manjarrez, J. R. 2005. Large-area maize yield forecasting using leaf area index based yield model. Agron. J. 97:418-425. 3. Duvick, D. N., and Cassman, K. G. 1999. Post-green revolution trends in yield potential of temperate maize in the north-central United Statees. Crop Sci. 39:1622-1630. 4. Leeper, R. A., Runge, E. C. A., and Walker, W. M. 1974. Effect of plant-available stored soil moisture on corn yields. I. Constant climatic conditions. Agron. J. 66:723-728. 5. Leeper, R. A., Runge, E. C. A., and Walker, W. M. 1974. Effect of plant-available stored soil moisture on corn yields. II. Variable climatic conditions. Agron. J. 66:728-733. 6. Morgan, C. L. S., Norman, J. M., and Lowery, B. 2003. Estimating plant-available water across a field with and inverse yield model. Soil Sci. Soc. Am. J. 67:620-629. 7. Runge, E. C. A., and Benci, J. F. 1975. Modeling corn production: Estimating production under variable soil and climatic conditions. Pages 194-214 in: Proc. of the 30th Ann. Corn and Sorghum Res. Conf. Am. Seed Trade Assoc. Washington, DC. 8. Runge, E. C. A., and Benci, J. F. 2005. Simulation of modern day corn yields for weather that occurred during the past century for 11 Corn-Belt, 1 Oklahoma, and 7 Texas locations. Agron. Abstr., 2005 Annual Mtg., Nov. 6-10, Salt Lake City, UT. 9. Runge, E. C. A., and Benci, J. F. 2008. Forecasting corn yield for eleven states in the corn belt: Results for 2001-2005. Online. Crop Management doi:10.1094/CM-2008-0609-03-RS. |
