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July 30-230-Christopher Miller


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2019 SWCS International Annual Conference
July 28-31, 2019
Pittsburgh, Pennsylvania

Published in: Environment
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July 30-230-Christopher Miller

  1. 1. Strategies to Minimize the Impacts of Coastal Flooding and Saltwater Inundation on Cropland
  2. 2. USDA-NRCS Climate Change Vulnerability Assessment and Adaptation Plan-2014 Key Climate Change Predictions: – Coastal storms are expected to increase in frequency and intensity leading to greater wave heights (storm surges), coastal flooding and damage. – Sea Levels are projected to continue rising over the next 40 years or more. Resulting Impacts: – Increased salinization of near-coastal waters – Increased flooding frequency of marginal lands – Changes in plant adaptability in specific locations due to environmental shifts – Increased competition from weeds/invasive plants – Increased soil health challenges due to potential increased erosion and changes in soil chemical and biological processes.
  3. 3. State’s Identified NRCS Plant Materials Needs 2014-2015 Saltwater buffer recommendations for marginal cropland/edge of field. Explore alternative crops for production. (DE, NC) Need more refined coastal plant selection guidelines. (RI) Plant recommendations for saltwater intrusion-determine upper salinity tolerances of coastal species. (DE, NJ) Address shoreline/streambank erosion in areas adjacent to cropland. (NC, NY, VA) Control/Suppress spread of invasives like Phragmites into production fields by incorporating native plants, preferably. (CT)
  4. 4. Financial + Technical Assistance Financial + Technical assistance working together = More conservation on the ground Cape May Plant Materials Center
  5. 5. USDA Climate Hubs Project Christopher Miller-NRCS Project Liaison Managing the impact of saltwater inundation from coastal flooding, will require producers to use more adaptive agricultural practices. This project will: 1. Provide assessment guidelines for agricultural producers in vulnerable coastal areas of the Eastern US and Gulf Coast. 2. Based on the assessment, provide potential mitigation (short term), adaptation (long term) or wetland/floodplain easement options in order to reduce lost farm and forest productivity. 3. Establish pilot plant materials demonstration and evaluation plantings to help determine various plant species’ adaptability to salt affected fields.
  6. 6. Vulnerability Assessment of Coastal Flooding Source: Titus, James G. and Charlie Richman. Map of Lands Vulnerable to Sea Level Rise: Modeled elevations along the U.S. Atlantic and Gulf Coasts. Climate Research, Vol. 18, November 2001
  7. 7. Sod Production in southern NJ Impacted by Sea Level Rise and Salts
  8. 8. Vulnerable Agriculture in Coastal Areas Ablemarle-Pamilco Sound-North Carolina
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  10. 10. What happens when farming stops?
  11. 11. Corn field impacted by flooding Phragmites invasion Prevent the establishment of invasive undesirable plant species and encourage the establishment of desired wetland plants.
  12. 12. Saltwater Intrusion as Driver of Agricultural Land Use Change 1992-2017 Agricultural land more likely to have transitioned to natural land when: • Close to coastal waters • Low elevation (with respect to sea level) • High coastal flood frequency • Higher salinity waters nearby (salinity by distance interaction) • Higher salinity coastal flooding (salinity by flood frequency interaction) Increased SWI Ref.-Becky Epanchin-Niell, Resources For The Future
  13. 13. Drivers of Saltwater Intrusion Reference: The Invisible Flood: The Chemistry, Ecology, and Social Implications of Coastal Saltwater Intrusion. Bioscience:May 2019
  14. 14. • Saltwater intrusion results in complex biogeochemical changes in the soil • Legacy N and P are released and moving from fields to marshes. • Carbon sequestration increased at field edges and along ditches. Field edges will migrate inland. Tully and Gedan, UMD/GWU Research
  15. 15. Mitigation of Salt Affected Soils Potential relatively short term, quick fixes*: – Allow excess salts to leach through natural rainfall events or irrigate with fresh water. • Incorporate rotations of salt tolerant crops alternating with applying water. – Add gypsum-Conservation Practice Code 333-Amending Soil Properties with Gypsum Products. Not as effective on sandy soils with lower CEC – Incorporate composts that don’t contain salts. • Avoid sewage sludge, most manures and mushroom compost – Grow cover crops for one season or in rotations • Small grains esp. barley, Triticale, sorghum, sorghum/sudangrass, canola, some millets and tall wheatgrass have especially good salt tolerance. *Site/soil specific, as well as producer specific
  16. 16. Let’s Focus on Opportunities
  17. 17. Potential Adaptation Strategies
  18. 18. Adapt Crop Salinity tolerance (ppt) sweet potato 0.8 corn 0.9 tomato 1.3 soybean 2.7 wheat/barley 3.3/8.0 sorghum 5.6 GMO salt tolerant soy 6.0 canola/rapeseed 7.0 switchgrass 17.5 salt marsh hay 63.0 Conventional crops Alternative crops Restoration candidate species Groundwater salinity = 3 – 20 ppt
  19. 19. Growing/Establishing Conservation Plants on Marginal Lands Establish saltmeadow cordgrass (Spartina patens) for harvesting as a salt hay (mulch) crop. Plant a biomass/fiber crop as a multifunctional buffer – Switchgrass (Panicum virgatum) – Coastal Panicgrass (Panicum amarum var. amarulum) – Prairie cordgrass (Spartina pectinata) – Seashore mallow (Kosteletzka virginica) Harvest native shrub stems for soil bioengineering applications on brackish shorelines – Groundsel bush (Baccharis halimifolia) – High tide bush (Iva frutescens), sweetfern (Comptonia peregrina), Arrowwood (Viburnum spp.), Indigobush (Amorpha fruticosa) – Willow (Salix spp.)-identify salt tolerant selections
  20. 20. Marshy Hay Cordgrass a.k.a. salt hay (Spartina patens) Once harvested from the natural marsh for salt hay. Valued as a weed free mulch. Demand is still high but supply is low resulting in high cost. Varietal selections being evaluated.
  21. 21. Native Grass Biomass Species High Tide Switchgrass Southampton Prairie Cordgrass Eastern gamagrass
  22. 22. NRCS Plant Materials/ARS Riparian Buffer Study-Field Trial
  23. 23. Native Warm Season Grass Riparian Zone Study(w/USDA-ARS) Cultivar Survival (2006) Vigor (2006) Yield (2005) Overall Relative ranking (1=best, 9=worst) Red River PC* 1 1 4 2.0 Hightide SG* 2 3 1 2.0 NY EG * 4 2 2 3.0 Shelter SG 3 4 3 3.3 Osage IG 7 5 7 6.3 Niagara BB 5.5 6 8 6.5 Suther BB 5.5 8.5 6 6.7 Suther IG 8 8.5 5 7.2 Bonilla BB 9 7 9 8.3 * Salt tolerant species
  24. 24. Seashore mallow
  25. 25. Planting in tilled sandy loam on the same farm. Planting Seashore Mallow in a no-till setting on the Freeman farm in Sussex County, Delaware. Seeding a Restoration Crop in the Transition Zone
  26. 26. Controlling Invasive Species Spread Strategic planting of competitive native species to control phragmites: – Spartina pectinata (prairie cordgrass) – Spartina patens (saltmeadow cordgrass) – Panicum virgatum (switchgrass) – Tripsacum dactyloides (Eastern gamagrass) – Kosteletzkya virginica (Seashore Mallow) – Other potential species to add: • Spartina cynosuroides (giant cordgrass) • Sporobolus virginicus (seashore dropseed) • Arundinaria gigantea (giant cane) • Iva frutescens (High tide bush)* • Baccharis halimifolia (Groundsel)*
  27. 27. It’s ALL in the ROOTS! Eastern Gamagrass Willow Switchgrass
  28. 28. Transitioning Refreshable Buffer Zones Abundant fine roots for nutrient absorption. Harvesting refreshes capacity for retention. Source: Jack Gallagher, University of DE
  29. 29. Conventional/Historical “Wisdom” Seawater/Saline incursions/Occurrences Detrimental-to-Disastrous for Agriculture Unconventional Saline Agriculture is a Viable-to-Desirable Alternative to Conventional Agriculture Source: Dennis Bushnell, Chief Scientist, NASA- Langley Research Center
  30. 30. Saltwater Intrusion into Farmland • A local, as well as a global, issue • Saltwater intrusion affects significant areas of the coastal counties of the East and Gulf Coasts. • Investigating options for farmers affected by saltwater intrusion (Chesapeake Bay MD, VA/Albemarle-Pamlico Sound, NC) • Working to provide NRCS/District conservation planners and producers with more information on the costs and benefits of various alternative choices
  31. 31. Technical Resources USDA Climate Hubs - USDA-NRCS Plant Materials Program- USDA-NRCS- Cooperative Extension Service (state specific)
  32. 32. BMP’s for Coastal Resilience Select plant species that are tolerant to salinity changes and increased temperature. Planting flood and salt tolerant plants inland from wetland systems to prolong viability to rising waters and increased flood frequency (in tidal systems). Maintaining and enhancing diversity of plantings to help with changing salinity and flooding conditions. Source: Maryland’s Adaptation Website:
  33. 33. Classification Electrical Sodium pH Conductivity Adsorption (dS/m) Ratio (SAR) Saline >4.0 <13 <8.5 Sodic <4.0 >13 >8.5 Saline-Sodic >4.0 >13 <8.5 Interpretation of electrical conductivity EC (dS/m) Salt rank Interpretation 0-2 Low Very little injury to plants 2-4 Moderate Sensitive plants may suffer 4-8 High Non-salt tolerant plants will suffer 8-16 Excessive Only salt-tolerant vegetation will grow 16+ Very Excessive Very few plants will grow Salt Affected Soil Classification
  34. 34. Biogeochemical Effects of Salinization Increased ionic strength • Osmotic stress → plant stress or death • Ion exchange → nutrient mobilization Alkalinization • pH change → phosphorus release from acid soils • Clay dispersion → prevent drainage • Cation bridging → change carbon dynamics Sulfidation • High sulfate → reduced carbon storage • Sulfide toxicity → plant stress/death • Formation of iron-sulfur minerals → phosphorus release