Water Table Management

Transcription

1 Managing Agricultural Drainage Systems For Water Quality Improvements in the Midwest: Addressing Nitrate Leaching and Liquid Manure Application on Drained Cropland Dr. Larry C. Brown Professor, Extension Agricultural Engineer Department of Food, Agricultural, and Biological Engineering College of Food, Agricultural, and Environmental Sciences The Ohio State University Source Areas of Nitrogen to Gulf of Mexico and Great Lakes USGS Water Table Management Conventional Drainage Controlled Drainage Subirrigation 1

2 Drainage Water Management USDA-NRCS Practice Code 554 Drainage Water Management National Standard Primary focus has been Midwest for improving water quality by reducing nitrate loads Very good practice with manure application standard Ohio 554 practice is EQIP-eligible practice We recommend artificially Raising the Outlet Elevation Managing We the do Outlet NOT recommend Elevation Plugging not Plugging the Outlet! the Outlet Drainage Water Management NRCS Practice Standard 554 2

3 Water control tructures Two management zones From Ghane, Gunn, Shang, Shedekar, Wahl, Brown, Fausey, FABE/OSU, USDA-ARS Water Quality and Quantity Impact On appropriate landscapes, we expect up to a 50% reduction in Annual Nitrate Loads, on average, by Managing Agricultural Drainage Systems on appropriate sites in Ohio Change in Outflow Volume leads to a similar Change in Nitrate-Nitrogen Load Minimal change in Nitrate Concentration 3

4 Controlled Drainage Drainage Water Management NRCS Code 554 Benefits 1. Drainage Water Conservation 2. Potential Water for Crop Use; Thus potential for Improvement in Crop Yields 3. Water Quality Improvement in Drainage Discharge 4. Cost Share Opportunities (EQIP, others) 5. Potential Improvement in Riparian Channel Baseflow 6. Potential Improvement in Recharge 7. Excellent Application for Manure Application on Drained Cropland 8. Others Controlled Drainage (Drainage Water Management NRCS Code 554 Potential Negative Aspects These result primarily from Poor Management, Poor Construction, or Combination of Both! 1. Increased Runoff and Soil Erosion 2. Limited or No Supplemental Water for Crop Use 3. Reduced Crop Yields 4. Poor or No Water Quality Benefit 5. Cost Share $ (if used) Wasted; or Your $ Wasted! 6. Others? 4

5 From Justin McBride, NW Ohio From Justin McBride, NW Ohio Proper Installation and Maintenance is Important Structure should be placed on solid, undisturbed earth (no gravel) Use anti-seep collar Hand backfill; Do not backfill or compact by machine Use recommended fittings and pipe; Joints should be water tight Use non-perforated pipe on both sides of structure, approx. 20 ; no gravel or sand Minimal maintenance, but check gaskets on flashboards regularly; Replace gaskets if worn; Grease tracks; Keep flashboards and tool available 5

6 From NRCS, with revisions by Dr. Norman Fausey, USDA-ARS Soil Drainage Research Unit, Columbus Controlled Drainage Applications (Drainage Water Management) on Sites where Liquid Manure and Milking Center Wastewater are applied on Subsurface Drained Cropland 6

7 For Land Application of Liquid Manure using Drainage Water Management, Proper Installation and Maintenance are even more Important! Structure placed on solid, undisturbed earth (no gravel) Use anti-seep collar Hand backfill; Do not backfill or compact by machine Use recommended fittings and pipe; Joints water tight Use non-perforated pipe on both sides of structure, approx. 20 ; no gravel or sand Minimal maintenance; Check gaskets on flashboards regularly; Replace gaskets if worn; Grease tracks; Keep flashboards and tool available Follow NRCS design recommendations for observation and pump out storage Anti-seep collar From Nic Stacey, NW Ohio 7

8 Structure Installed Too Close to Bank Edge No Anti-Seep Collar; Thus Leakage, and Potential Failure Locate Structure to avoid Machinery Operations; Take Advantage of Buffer Areas Poor Installation; Structure and Pipe Connections improperly sealed; Gravel Layer Placed Below the Outlet Pipe and Structure Thus Leaks Excessively. Poor Installation Led to an Illicit Discharge and Fines to Landowner For situations where applied liquid reaches control structure at outlet too quickly, consider adding detention at outlet, with port holes to pump out liquid, then reapply. Ohio NRCS can provide design aspects (see next slide). 8

9 Dr. Larry C. Brown Professor, Extension Agricultural Engineer Department of Food, Agricultural and Biological Engineering College of Food, Agricultural, and Environmental Sciences The Ohio State University Agricultural Water Management 9