COMPARISON OF SURFACE WATER QUALITY AND YIELDS FROM ORGANICALLY AND CONVENTIONALLY PRODUCED SWEET CORN. Josh Edgell NC State University

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1 COMPARISON OF SURFACE WATER QUALITY AND YIELDS FROM ORGANICALLY AND CONVENTIONALLY PRODUCED SWEET CORN Josh Edgell NC State University

2 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

3 Introduction Water Quality Agriculture is one of the leading sources of impairment for the nation s waterways. Sediment Pathogens Organic enrichment Nutrient enrichment Habitat alterations The National Water Quality Inventory: Report to Congress, 2004 Neuseriver.org

4 Introduction Tillage and Water Quality Conventional Tillage One or multiple passes with plow, disk or harrow Leaves little to no crop residue on soil surface...the main function of cultivation in corn is weed control - K. Buchholtz, 1968 Conservation Tillage Retains at least 30% crop residue on soil surface after planting Often used in combination with no-till, or other forms of reduced soil disturbance...conservation tillage is one of the most effective and efficient means of reducing soil erosion. - M. G. Cook, PhD, 1989

5 Introduction Organic Farming Management Organic production prohibits: Petroleum-based fertilizers Sewage sludge-based fertilizers The use of genetic engineering Most conventional pesticides Specific guidelines for substance use are found in The National List of Allowed Synthetic and Prohibited Non- Synthetic Substances All substances and organic labels are regulated by the Organic Foods Production Act of 1990 and the National Organic Program

6 Introduction Organic Defined...based on minimal off-farm inputs......maintain and enhance ecological harmony....minimize pollution from air, soil and water.... optimize the health and productivity of interdependent communities of soil life, plants, animals and people. USDA National Organic Standards Board (NOSB), April 1995

7 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

8 Objective To compare organic and conventional agriculture in till and no-till systems with a focus on: Agronomic Data Sweet Corn Yield Water Quality Field Runoff

9 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

10 Location Located at the Mountain Horticultural Crops Research Station - Mills River, NC

11 Plot Design 20 Plots (4 replications of 5 Treatments) Conservation tillage (no-till) with conventional production NT/Conven Conventional tillage with conventional production CT/Conven Conservation tillage (no-till) with organic production NT/Org Conventional tillage with organic production CT/Org Control conventional tillage with no added nutrients (removed for analysis)

12 Plot Design Completely Randomized Design Average Plot Slope CT/Conven 3.5% CT/Org 4.4% NT/Org 4.3% NT/Conven 4.3%

13 Plot Design 30 ft 1800 sq ft 1800 sq ft 60 ft 167 sq m 167 sq m 10 ft

14 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

15 Materials & Methods Sweet Corn Fertilizer Rates (except nitrogen) are based on yearly soil analysis. Nitrogen rate Conventional - commercial fertilizer (33-0-0) + winter wheat residue Organic - pelletized poultry litter (MicroStart 4-2-3) + leguminous cover crop residue Sweet Corn Variety Luscious 75 day Plant - May Harvest - August Insecticide Conventional - Warrior Organic Entrust Treatment Ammonium Nitrate Cover Crop N Poultry Littler N Applied P Ammonium Nitrate Cover Crop N Poultry Littler N Applied P kg ha-1 CT/Conven NA NA 0 NT/Conven NA NA 0 CT/Org NA NA NT/Org NA NA Larsen et al. (2012) Applied P from poultry littler and conventional fertilizers for organic and conventional treatments respectively

16 Materials & Methods Phosphorus Index

17 Materials & Methods Sweet Corn Yield Measurements are made from two center rows Separated into marketable and cull ears Ears are measured and weighed Yields expressed in kg/ha

18 Materials & Methods Organic Cropping Systems Weed Control No herbicide used in organic systems Conservation no-till - mowed between rows until corn canopy is established (early June) Conventional tilled Chisel plow and disking; roto-tilled betweenrows until corn canopy is established Conventional Cropping Systems Conventional tilled Chisel plow and disking Conservation no-till - Roundup (cover crop termination) Pre-emergence (Bicep II Magnum)

19 Materials & Methods Cover Crop Management Cover Crop Conventional Systems Winter Wheat Organic Systems Crimson Clover and Winter Wheat Plant October Terminate - April NT/Conven Round-up CT/Conven Flail chopped and incorporated NT/Org Flail chopped CT/Org Flail chopped and incorporated

20 Materials & Methods Water Quality Non-point source pollution: Field Surface Runoff Runoff samples are collected with ISCO samplers Analyzed for: Total suspended solids (TSS) Total phosphorus (TP) Dissolved phosphorus (DP) Total Kjeldahl nitrogen (TKN) Ammonium-Nitrogen (NH4-N) Nitrate-Nitrogen (NO3-N) Total dissolved nitrogen (TDN)

21 Materials & Methods Agricultural Cropping Efficiency (ACE) Coefficient Allows for a better comparison of cropping systems biased upon what is gained as well as lost Expressed as Total Crop Yield Nutrient Loss Higher values represent greater agricultural gain per unit of potential negative environmental impact Unit-less

22 Materials & Methods Data Analysis SAS software, SAS Institute Inc, Cary, NC Data was analyzed by year due to year-to-year variation To test tillage and cropping system, Control treatment was removed (2x2 Factorial) Data transformations were used to ensure normality

23 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

24 Results Water Quality: Total Suspended Solids

25 Results Water Quality: Runoff

26 Results Water Quality: Total Phosphorus

27 Results Water Quality: Total Kjeldahl Nitrogen

28 Results Water Quality: Dissolved Phosphorus

29 Results Water Quality: Nitrate-Nitrogen

30 Results Water Quality: Ammonium-Nitrogen

31 Results Water Quality: Total Dissolved Nitrogen

32 Results Sweet Corn Yield Larsen, E., J. Grossman, J. Edgell, G. Hoyt, D. Osmond, S. Hu Soil Biological Properties, Soil Losses and Corn Yield in Long-Term Organic and Conventional Farming Systems. Soil Tillage Res. 139:37-45

33 Results ACE Coefficient Agricultural Cropping Efficiency = Total Crop Yield Nutrient Loss Allows us to compare treatments based on what we lose as well as what we gain The large range in coefficients made normalization a necessity Largest value set to 100 Remaining values proportioned to it

34 Results 2011 ACE Coefficient Constituent TSS TP DP TKN NH 4 -N NO 3 -N TDN CT/Conven 2b* 6c 48a 10b 16b 9 16b TRT CT/Org 4b 4c 4c 9b 14b 23 14b NT/Org 37a 14b 14b 21b 22b 64 26b NT/Conven 100a 100a 100a 100a 100a a P-Value <0.001 <0.001 <0.001 <0.001 <0.05 >0.05 <0.05 *Means followed by same lowercase letter are not significantly different (P>0.05)

35 Results 2012 ACE Coefficient Constituent TSS TP DP TKN NH 4 -N NO 3 -N TDN CT/Conven 6b 17b 90a 16b TRT CT/Org 10b 9b 13b 14b NT/Org 16b 11b 10b 16b NT/Conven 100a 100a 100a 100a P-Value <0.001 <0.001 <0.001 <0.01 >0.05 >0.05 >0.05 *Means followed by same lowercase letter are not significantly different (P>0.05)

36 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

37 Conclusion Water Quality Tillage driven losses: Sediment Total Phosphorus Total Kjeldhal Nitrogen Ammonium Total Dissolved Nitrogen Cropping system driven losses: Nitrate Dissolved Phosphorus Most likely due to the high P content of the organic fertilizer In no-till systems organic fertilizer remains on soil surface

38 Conclusion Sweet Corn Yields Highest in conventional systems: 2011 Yields were 5 to 8 times greater in conventional systems 2012 Yields were 1.5 to 14 times greater in conventional systems Lower yields in organic systems were associated with: Higher weed pressure in all organic plots Higher weed pressure in no-till organic Lower plant available nitrogen

39 Conclusion ACE Coefficient NT/Conven had the highest ACE coefficient across all measured constituents in both years Data suggests NT/Conven as the most efficient treatment in concerns to crop yield and water quality Future Work Similar research should be conducted with more comparable nitrogen rates Development of cropping systems that utilize ideals from both organic and conventional practices

40 Outline Introduction Objective Location & Plot Design Materials & Methods Results & Discussion Conclusion Acknowledgements

41 Acknowledgements Dan Line Joy Smith Erika Larsen Wesley Childres Sara Seehaver Collin Suttles Zan Price Jason Zink The staff of MHCRS USDA NIFA

42 Questions

43 Supplemental Data Surface Runoff Rainfall Erosion Index Values Avg Winter GS May-June Wischmeier, W., and D. Smith Predicting Rainfall Erosion Losses A Guide to Conservation Planning. USDA Handbook. Government Printing Office, Washington, D.C

44 Supplemental Data Nutrient Concentrations TSS System*Tillage interaction both years TP Tillage effect 2011; System effect 2012 DP System*Tillage 2011; System effect 2012 TKN No statistical difference NH4-N No statistical difference NO3-N System effect both years TDN No statistical difference TOC Tillage effect 2011; System effect 2012