Understanding and Managing Corn Yield Potential

1. Understanding and Managing CornYield Potential

2. Investigators Timothy J. Arkebauer Environmenal crop physiology Kenneth G. Cassman Crop physiology and plant nutrition Rhae A. Drijber Soil microbial ecology Achim Dobermann Soil fertility and plant nutrition John L. Lindquist Corn ecophysiology & modeling John P. Markwell Biochemistry Lenis A. Nelson Plant breeding and crop production James E. Specht Soybean genetics Daniel T. Walters Soil fertility, C sequestration Haishun Yang Crop modeling Funding provided by: Foundation for Agronomic Research (PPI, IMC Global) Fluid Fertilizer Foundation Nebraska Corn Board

3. U.S. Corn Yields 1964 - 2001 Source: Annual USDA cropping practices surveys of >2000 farms

4. Fertilizer N Use on Corn, 1964 - 2000 Source: Annual USDA cropping practices surveys of >2000 farms

5. Fertilizer P Use on Corn, 1964 - 2000 Source: Annual USDA cropping practices surveys of >2000 farms

6. Fertilizer K Use on Corn, 1964 - 2000 Source: Annual USDA cropping practices surveys of >2000 farms

7. Why Research on High Yields? • Can we be satisfied with what has been achieved? • Will it be easy to maintain the yield growth rates achieved in the past? • Can we design more efficient systems in which yields close to the potential are achieved with moderate-high amounts of nutrient input? • How energy-efficient are such systems? • Can such systems play a positive role for the local and global environment?

8. Existing Corn Yield Gaps

9. Crop Region N fertilizer (kg/ha) RE (% of applied) mean (+/- SD) mean (+/- SD) Corn USA 103 (85)* 37 (30) (corn-soybean) Rice Asia 117 (39)** 31 (18) (rice-rice) 112 (28)*** 40 (18) *on on-farm measurements at 55 sites in the Corn Belt **on on-farm measurements at 179 sites in Asia ***field-specific nutrient management at 179 sites in Asia Fertilizer-N Uptake Efficiency (RE) of Corn and Rice Source: Cassman, Dobermann and Walters, Ambio 31 (2002), 132-140

10. The Ecological Intensification Experiment at Lincoln, NE • Understand the yield potential of corn and soybean and how it is affected by management. • Develop a scientific basis for extrapolation to other locations based on understanding of the key yield-determining processes. • Develop practical technologies for managing systems at 70-80% of the yield potential. • Conduct integrated assessment of productivity, profitability, input use efficiency, energy balance, and environmental consequences.

11. Experimental Details: Lincoln, NE Soil: Kennebec silt loam Irrigation: drip irrigation

12. Fertilizer Program: Corn Continuous corn (CC): CC - M1: 174 lb N/acre (195 kg/ha), no P, no K CC - M2: 283 lb N/acre (317 kg/ha)*, 92 lb P2O5/acre (45 kg P/ha) and 93 lb K2O/acre (85 kg K/ha) * includes fall application of 65 lb N/acre in 2001 Corn after soybean (CS): CS - M1: 116 lb N/acre (130 kg/ha) , no P, no K CS - M2: 219 lb N/acre (245 kg/ha) , 92 lb P2O5/acre (45 kg P/ha) and 93 lb K2O/acre (85 kg K/ha)

13. Corn Grain Yield, Lincoln, NE 1999-2002 CS-high-M2 and CC-high-M2: P2 density in 2000, P3 density in 1999, 2001, 2002 Line: average irrigated corn yield in Nebraska

14. Climatic Conditions at Lincoln, NE

15. Effect of Plant Density and Nutrient Management on Corn Grain Yield, 1999 28,300 35,700 44,200 plants/acre

16. Corn Grain Weight per Ear as Affected by Plant Density and Nutrient Management CS and CC, 1999-2001

17. Total Crop model Grain Stover biomass HI --- --- -- - -- - --- Mg dry matter/ha -- --- -- - -- -- --- Measured (EI trial) 13.2 13.2 26.4 0.50 Ceres - Maize 12.4 11.0 23.4 0.53 Muchow - Sinclair 11.4 11.4 22.8 0.50 Intercom 9.7 9.0 18.7 0.52 Hybrid - Maize 13.1 13.2 26.3 0.50 Simulated vs. Actual Corn Growth Treatment CS-P2-M2, averages of 1999-2001

18. Nutrient Uptake and Removal

19. Nitrogen Use Efficiency 1 M2 treatment with highest-yielding plant density. 1999, 2001 and 2002: P3; 2000: P2. NUE = partial factor productivity of N

20. Nitrogen Uptake Efficiency: Corn 1999 % fertilizer-N recovered in plant (grain + stover), measured by difference method.

21. Residual Soil Nitrate-N in Spring 1 M2 treatment with highest-yielding plant density. 1999, 2001 and 2002: P3, 2000: P2. 2 Residual nitrate measured after corn as previous crop. 3 Residual nitrate measured after soybean as previous crop. 4 Effect of application of 73 kg N/ha in fall 2001, sprayed on crop residue in CC-M2 treatments only. 60% of this residual nitrate was in the top 12 inches of soil.

22. Carbon Input from Crop Residues 4-year period (1999 to 2002), aboveground crop residues

23. 2002 Soil C2O Emissions Vented closed chamber + photoaccoustic trace gas analyzer, fluxes measured a.m.

24. 2002 Soil N2O Emissions Vented closed chamber + photoaccoustic trace gas analyzer, fluxes measured a.m.

25. Conclusions • Corn yield potential varies across locations, from year to year and within a year (planting date). Variation must be understood to exploit yield potential through management. • Interactions between climate, plant density, and nutrient status determine yield potential and how much of it can be achieved under field conditions. • To achieve corn yields near potential ceilings requires higher plant density (35-40,000 plants/acre) and greater N and K uptake per bushel yield. • More dynamic approaches to N management are required to achieve high N fertilizer efficiency and minimize losses. • High-yielding corn systems increase soil C sequestration, possibly without increasing soil greenhouse gas emissions.

26. Outlook • Fine-tune crop management. Improve soil GHG measurements. Conduct whole systems analysis. • Comparison of high-yield corn sites: Lincoln NE vs. Manchester IA (F. Childs). • Further develop the Hybrid-maize model and release it as a management tool. • Conduct regional analysis of corn yield potential and C sequestration scenarios: tillage vs biomass (Nebraska, whole Corn Belt). • Incorporate findings into fertilizer recommendations.