A Nutrient Mass Balance of the Watershed Research and Education Center: Where, When and How Much? BRIAN E. HAGGARD, JOHN T. METRAILER, DIRK PHILIPP, J. VAUGHN SKINNER, J. THAD SCOTT, AND ANDREW N. SHARPLEY
I am just glad to be here!
Watershed Research and Education Center The Watershed Research and Education Center is an experimental watershed, that is highly instrumented. The Watershed is on the Arkansas Agricultural Research and Extension Center in Fayetteville. The Watershed is unique it is located at the interface of agriculture and urban development.
Watershed Research and Education Center The research focus is on ways to minimize nutrient loss from the landscape, while maintaining sustainable agricultural production. The Watershed will provide the opportunity to evaluate specific conservation practices (e.g., BMPs) and to show case these practices in place, especially riparian buffers.
The study fields were setup to follow hydrologic boundaries. Field level watershed units under individual management strategies.
Environmental Stewardship Historically, there was no intact riparian zone along the streams running through the Watershed. We restored the riparian zone along the fluvial channel, showing different buffers in Fall 28.
But, we did not count on mother nature testing our efforts... She gave us THE ICE STORM of January 29.
Here s what it looks like now (212). Same large Oak in previous pictures.
WREC is gaged at six sites throughout the watershed. Site 6 Outlet Site 5 Wetland Site 3 Site 4 Agricultural and Urban Site 1 Site 2 Urban APRIL 211
Flow and water chemistry are monitored at WREC. Stage is measured and recorded in 15 minute increments. 28-21: US Geological Survey ran the WREC gages (~27,$ yr -1 ) 21-212: We manage the WREC gages now due to fiscal constraints Approximate weekly water quality data has been collected from 29 to present. Samples are analyzed for Cl, NH 4 -N, NO 3 -N, TN, SRP, TP and TSS
Discharge at WREC is controlled by precipitation. 1e+2 Average Discharge (cfs) Rainfall (mm) Storage (cfs) 1e+1 Site 6 1e+ Site 1 1e-1 1e-2 Site 2 1e-3 Site 3 1e-4 1e-5 29 21 211 212 Dec Jun Dec Jun Dec Jun Dec 2 Retention -2 Export -4-6 -8 29 21 211 212 Dec Jun Dec Jun Dec Jun Dec 5 4 3 2 1 29 21 211 212 Dec Jun Dec Jun Dec Jun Dec Date (month) Flows are consistent with rainfall patterns. August 21 only received.4mm rainfall April 211 flood! And with ground moisture conditions. July 21 (319 mm & 2.9 cfs) June 21 was dry 36 mm May 211 (211 mm & 3. cfs) April 211 was wet, flooded!
Total nitrogen was variable between sites, but the greatest input was from [agricultural] Site 1. TN FAC (LOESS Residuals) 1..5. -.5-1. 1 1 1 1 1 29 21 211 Site 3 1..5. -.5 Time (days) Site 6-1. 2 4 6 8 1 12 2 4 6 8 1 12 Time (days) 212 29 Annual TN Loads (kg) 21 CY 29 CY 21 CY 211 211 212 Site One Site Two Site Three Site Six TN concentrations ranged from.2-3.7 mg/l. The relation between discharge and concentration varied by site. Concentrations significantly increased over time at Site 1 (agriculture), but decreased over time at Site 3 (wetland). Loads pattern were similar to discharge. Greatest input also from Site 1 (71-96 kg/yr) and least from Site 2 (17-22 kg/yr). Urban areas provided the least input to WREC.
Nitrogen Yields at WREC Nitrogen yields 9-11% NH 4 -N 17-46% NO 3 -N Site 1 (Agriculture) Highest inflow (row crop) Site 2 (Urban) Lowest inflow (old residential and apartments) Site 3 (Wetland) Low inflow Site 6 (Pasture/Outlet) Highest yields Likely influenced by previous land use Estimated Average Riverine Yields for TN (kg/ha-yr) 8. 7. 6. 5. Site One Site Two 4. Site Three Site Six 3. 2. 1..
Total phosphorus was variable across sites, and the largest input was from [agricultural] site 1. TP concentrations ranged from.1-1.7 mg/l. Concentrations increased with runoff, but decreased with increasing base flow. No significant changes in concentration were observed over time. But seasonal variation was observed at Sites 1 (urban) and 3 (wetland). Annual loads were similar to SRP and followed the pattern of discharge. Greatest input through Site 1 (26-7 kg/yr, agriculture) And least input through Site 2 (4.1-5.5 kg/yr, urban). TP FAC (LOESS Residuals) 1-1 29 1 1 21 211 Time (days) Site 1 212 2 4 6 8 1 12 1 1 1 TP FAC (LOESS Residuals) 1-1 29 Annual TP Loads (kg) 21 CY 29 CY 21 CY 211 211 Time (days) Site 3 212 2 4 6 8 1 12 Site One Site Two Site Three Site Six
Phosphorus Yields at WREC Estimated Average RiverineYields for TP (kg/ha-yr) 4.5 4. 3.5 3. 2.5 2. 1.5 1..5. Site One Site Two Site Three Site Six Phosphorus yields 48-85% SRP Related to TSS Site 1 (Agriculture) Highest inflow (row crop) Site 2 (Urban) Lowest inflow (old residential and apartments) Site 3 (Wetland) Retain solids associated TP Site 6 (Pasture/Outlet) Highest values Likely influenced by previous land use Soil P accumulation
Total suspended solids concentrations were influenced by runoff. Log (Total Suspended Solids, TSS [mg/l]) Site 1 Site 2 3 3 2 2 1 1-3 -2-1 1 2 3-3 -2-1 1 2 3 Log (Discharge, Q [cfs]) Log (Discharge, Q [cfs]) Annual TSS Loads (kg) 1 1 1 1 1 1 Site One Site Two Site Three Site Six 1 CY 29 CY 21 CY 211 Concentrations ranged from.5-49 mg/l. Concentrations increased with increased stormwater runoff across all sites No significant changes in TSS were observed at any site over time, and TSS was not influenced by seasonal variation Loads pattern similar to discharge Greatest input through Site 1 (4,325-646 kg/yr) Least input through Site 2 (313-411 kg/yr)
Total Suspended Solids Yields at WREC Estimated Average Yields for TSS (kg/ha-yr) 1 9 8 7 6 Site One Site Two 5 Site Three 4 Site Six 3 2 1 TSS yields related to increased discharge Site 1 (Agriculture) Highest inflow (row crop) Site 2 (Urban) No major construction Grassed ditches, little bank failure Site 3 (Wetland) Retain solids Site 6 (Pasture/Outlet) Highest yields Possible soil erosion Degraded stream banks 28 field reorganization, ongoing tillage.
All constituents are being exported from WREC. Export = Outlet Inputs Export = (Sites 6-1 -2-3) Export patterns for nutrients and sediment were similar to discharge. Storage (kg) Storage (kg) 2-2 -4-6 SRP TP 29 21 211 212-8 Dec Jun Dec Jun Dec Jun Dec Jun 2-2 -4-6 ammonia nitrate TN 29 21 211 212-8 Dec Jun Dec Jun Dec Jun Dec Jun 5 RETENTION EXPORT retention export retention export retention Storage (kg) -5-1 TSS export -15 29 21 211 212-2 Dec Jun Dec Jun Dec Jun Dec Jun Time (month)
However, we need to consider all inputs to WREC not just the inflows So, what happened on the landscape? Landscape inputs include: Fertilizer and poultry litter Livestock Cattle Sheep Horses Pigs Atmospheric deposition Nitrogen fixation by legumes
Nitrogen Loads (kg) from Land Applications 6, FERTILIZER INPUTS 4, WET & DRY DEPOSITION N FIXATION 2, -2, 26 27 28 29 21 211 212 Pigs Sheep Fertilizer ADP Cattle Horses Legume Hay -4, -6, OUTPUTS HAY EXPORT
Phosphorus Loads (kg) from Land Applications 1, 8 FERTILIZER INPUTS 6 4 2-2 -4 FIELDS RESET 26 27 28 29 21 211 212 Pigs Sheep Fertilizer Atmospheric Depostion Cattle Horses Hay -6-8 -1, OUTPUTS HAY EXPORT
When we consider the landscape mass balance... Nutrients are generally exported [recently]. 4 2-2 -4-6 -8-1, -1,2-1,4-1,6 STORAGE N & P Loads (kg) 27 28 29 21 211 212 EXPORT HAY PRODUCTION! N P Large inputs of nutrients in 26 N= 9,74 kg P= 1,43 kg Large cattle presence and minimal hay exportation Nutrient export from WREC landscape via hay production Some nutrient accumulation
Future Plans for WREC Watershed Research and Education Center Riparian Activities RESTORE WETLANDS FARM PONDS
QUESTIONS? Site 6 Outlet Site 5 Wetland Site 3 Site 4 Agricultural and Urban Site 1 Site 2 Urban