Long-Term Agricultural Research: A Means to Achieve Resilient Agricultural Production for the 21st Century and Beyond - Liebman
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70th SWCS International Annual Conference July 26-29, 2016 Greensboro, NC
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Long-Term Agricultural Research: A Means to Achieve Resilient Agricultural Production for the 21st Century and Beyond - Liebman
- 1. . Agronomic, Economic, and Environmental Performance Characteris7cs of Conven7onal and More Diverse Cropping Systems in the U.S. Corn Belt Matt Liebman Iowa State University
- 2. Special thanks to: • C. Chase • A. Davis • R. Gómez • A. Heggenstaller • J. Hill • N. Hunt • D. James • A. Johanns • L. Leandro • F. Menalled • D. Sundberg • P. Westerman • C. Williams
- 3. Iowa produces huge amounts of corn, soybean, hogs, caLle, eggs, and ethanol.
- 4. But there are important challenges to long-‐term producOvity, profitability, and environmental quality. • Soil erosion • Water quality effects of nutrient emissions • VolaOlity in producOon costs and crop prices • Herbicide resistant weeds • Outbreaks of crop and animal diseases
- 5. 2011 Wright County, Iowa 0 1.42 2.84 4.26 miles Land Cover Categories Dby decreasing acreage- AGRICULTURE Corn Soybeans Grassland Herbaceous Alfalfa Other Hay/Non Alfalfa Oats Winter Wheat Sweet Corn Sod/Grass Seed Fallow/Idle Cropland Dbl Crop WinWht/Soybeans Rye Clover/Wildflowers Switchgrass NON-AGRICULTURE* Developed/Open Space Woody Wetlands Deciduous Forest Developed/Low Intensity Herbaceous Wetlands Open Water Produced by CropScape - http://nassgeodata.gmu.edu/CropScape * Only top 6 non-agriculturecategroies are listed. Iowa agriculture lacks diversity Corn and soybean: 63% of total IA land area, 82% of cropland Wright County, 2011 583 sq. miles (1,509 sq. km.) Yellow = corn Green = soybean USDA-‐NASS Cropland Data Layer
- 6. Haield et al., 2009, JSWC Alfalfa and other hay crops Small grains
- 7. Yield reducOon for major crops grown in shortened rotaOons or monoculture Crop Yield decline Barley (Hordeum vulgare) 11-19% Corn (Zea mays) 7-36% Oilseed rape (Brassica napus) 3-25% Potato (Solanum tuberosum) 10-30% Rice (aerobic) (Oryza sativa) 19-54% Soybean (Glycine max) 8-20% Sugarcane (Saccharum spp.) 3-50% Sweet potato (Ipomoea batatas) 21-57% Wheat (Triticum aestivum) 9-20% BenneL et al. (2012) Biological Reviews 87: 52-‐71
- 8. Can cropping system diversificaOon and crop-‐livestock integraOon: • reduce requirements for purchased inputs? • maintain or improve producOvity and profitability? • suppress weeds effecOvely? • reduce suscepObility to diseases? • improve environmental performance characterisOcs?
- 9. Iowa State University Marsden Farm, Boone Co., IA
- 10. Iowa State University Marsden Farm, Boone Co., IA 2-‐year rotaOon: corn-‐soybean 3-‐year rotaOon: corn-‐soybean-‐oat/red clover 4-‐year rotaOon: corn-‐soybean-‐oat/alfalfa-‐alfalfa 36 plots, 60’ x 275’ each all phases of each rotaOon present every year 2001 and 2002: base-‐line sampling 2003-‐2005: start-‐up period 2006-‐present: mature period
- 11. Management pracOces 2-‐year rota7on 3-‐year and 4-‐year rota7ons Manure None 7 tons/acre before corn Mineral N fer7lizer 100 lbs N/acre at planOng plus sidedress None at planOng, but with sidedress opOon Herbicides Broadcast in corn and soybean phases Banded with interrow culOvaOon in corn and soybean phases Tillage Chisel plow aker corn Moldboard plow aker clover and alfalfa, chisel plow aker corn
- 12. Mean annual mineral N ferOlizer and herbicide use, 2006-‐2014 N fer7lizer Herbicides 2-‐year 3-‐year 4-‐year 2-‐year 3-‐year 4-‐year lb N/acre lb a.i./acre Corn 147 23 20 1.41 0.06 0.06 Soybean 2 2 2 1.49 0.12 0.12 Oat -‐-‐ 2 2 -‐-‐ 0 0 Alfalfa -‐-‐ -‐-‐ 2 -‐-‐ -‐-‐ 0 RotaOon av. 74 9 6 1.45 0.06 0.05 ReducOon -‐88% -‐92% -‐96% -‐97%
- 13. Fossil energy use, 2006-‐2011 Johanns et al., 2012 Rota7on 2-‐year 3-‐year 4-‐year Fossil energy inputs (barrels of oil equivalent/acre) 0.61 a 0.24 b 0.26 b Fossil energy inputs (gal. of diesel fuel equivalent/acre) 25.4 a 10.2 b 10.8 b Major categories of fossil energy inputs were nitrogen fertilizer, gas for drying corn, and tractor fuel. Diversity à lower energy inputs
- 14. Crop 2-‐year 3-‐year 4-‐year Corn (bu/acre) 188 b 194 ab 197 a Soybean (bu/acre) 47 c 52 b 55 a Oat (bu/acre) -‐-‐-‐ 93 b 97 a Alfalfa (tons/acre) -‐-‐-‐ -‐-‐-‐ 4.1 Mean Yields, 2006-‐2014 Sources: Liebman et al., 2008; Gómez et al., 2012; Davis et al., 2012.
- 15. Mean weed biomass in 2006-‐2014 was low in corn and soybean phases of each system. Weed growth was greater in oat and alfalfa phases. 2-‐year rota7on 3-‐year rota7on 4-‐year rota7on Crop phase lb/acre Corn 2 a 7 a 5 a Soybean 1 b 7 a 3 ab Oat/legume -‐-‐-‐ 65 a 33 a Alfalfa -‐-‐-‐ -‐-‐-‐ 45 Within rows, means followed by different leLers are significantly different.
- 16. Labor and economics, 2008-‐2014 RotaOon 2-‐year 3-‐year 4-‐year Labor inputs (hr/acre) 0.7 c 1.1 b 1.4 a Gross returns ($/acre) 725 a 638 b 675 ab Costs of producOon, including labor ($/acre) 341 a 229 c 262 b Profits (returns to land and management, $/acre) 384 a 409 a 413 a Diversity à greater labor requirements, lower gross returns, lower costs, similar profits
- 17. EsOmated Sheet and Rill Erosion (RUSLE2) Tons per acre per year 2-‐year rotaOon: 1.36 3-‐year rotaOon: 1.08 (-‐21%) 4-‐year rotaOon: 0.88 (-‐35%)
- 18. Soil Quality Indicators in Corn (0-‐20 cm) Rota7on Par7culate organic maYer carbon Microbial biomass carbon Poten7ally mineralizable nitrogen mg POM-‐C cm-‐3 soil μg C g-‐1 soil mg PMN cm-‐3 soil 2-‐year 1.86 b 312.6 c 30.8 b 3-‐year 2.44 a 388.7 b 42.1 a 4-‐year 2.38 a 472.2 a 38.3 a Sources: Lazicki et al., in review; King, 2014. Soil managed with longer rota@ons has more POM-‐C, microbial biomass, and PMN.
- 19. Herbicide-‐related aquaOc ecotoxicity was two orders of magnitude lower in the more diverse rotaOons. 10 10 2 10 3 10 4 10 5 2006 2007 2008 2009 2010 2011 2-year 3-year 4-year Toxicitypotential(ComparativeToxicUnits) Year Davis et al., 2012
- 20. Serendipitous results from a long-‐term systems study
- 21. • Caused by a soilborne fungus -‐ Fusarium virguliforme • Root infecOon causes root rot and poor root vigor • Leaf symptoms caused by fungal toxins moved from roots to leaves • Disease favored by cool, wet weather • Yield losses can be severe Sudden Death Syndrome
- 22. RotaOon effects on soybean in 2010 during SDS epidemic: Longer rotaOons were healthier 3-‐year rota7on 2-‐year rota7on Measurements by L. Leandro, ISU Plant Pathology & Microbiology Photo courtesy of L. Miller
- 23. Mean SDS incidence and severity, 2010-‐2014, as affected by rotaOon system Rota@on effects were highly significant (p<0.001) Source: L. Leandro, ISU 0 10 20 30 40 50 2-year 3-year 4-year Incidence Severity SDSincidneceorseverity,% Rotation system
- 24. Insights from combining empirical measurements and modeling analyses in a systems science approach
- 25. InvesOgaOng weed dynamics with a pulse-‐chase approach 7m 7m 18m 84m Background seed bank densiOes determined in 2002 Weed seeds applied in Nov. 2002: 2000 giant foxtail m-‐2 + 500 velvetleaf m-‐2 ResulOng seed and plant densiOes measured for four years Velvetleaf Giant foxtail
- 26. -2500 -2000 -1500 -1000 -500 0 500 Changeinseeddensity(no.m-2) 2-yr 3-yr 4-yr Rotation length Giant foxtail -500 -400 -300 -200 -100 0 100 Changeinseeddensity(no.m-2) 2-yr 3-yr 4-yr Rotation length Velvetleaf Changes in Viable Seed Density 2002-2006 * * * * * a c b a b ab Liebman et al., 2008
- 27. Gryllus pennsylvanicus Dominant weed seed predators in central IA crop fields Peromyscus maniculatus
- 28. High rates of weed seed removal observed under field condiOons March-‐November, mean loss in two days: Velvetleaf (Abu@lon theophras@): 36% Giant foxtail (Setaria faberi): 56% (Heggenstaller et al. 2006) November-‐April, mean cumulaOve loss: Velvetleaf (Abu@lon theophras@): 77% Giant foxtail (Setaria faberi): 74% (Williams et al. 2009)
- 29. Spring Seedbank New Seeds Reproductive Adults Seedlings Seedling Recruitment Fe Seed Mortality Seedling recruitment Seedling survival Seed production New seed survival Seedbank survival Modeling analyses to invesOgate the effects of weed seed predators on weed populaOon dynamics
- 30. 0 2000 4000 6000 8000Seeddensity(no.m-2to20cmdepth) 0 5 10 15 20 25 Year Simulated Giant Foxtail Seed Density No Predation 4-yr rotation 2-yr rotation
- 31. 0 2000 4000 6000 8000 Seeddensity(no.m-2to20cmdepth) 0 5 10 15 20 25 Year Simulated Seed Densities Giant Foxtail in 4-year Rotation 20% predation 15% predation 10% predation 5% predation 0% predation
- 32. Cropping system diversificaOon and crop-‐livestock integraOon can comprise a viable strategy for reducing reliance on purchased inputs, suppressing weeds and certain diseases, improving soil quality, and maintaining yields and profits. Davis et al. 2012. PLoS ONE doi: 10.1371/journal.pone.0047149
- 33. Ecological processes, such as seed predaOon, play an important role in low-‐external-‐input systems. Davis et al. 2012. PLoS ONE doi: 10.1371/journal.pone.0047149