Improvements in Phase 5 Historical Look at Tributary Strategy Concerns and the mechanics of the Phase 5 Model

Tributary Strategy Concerns Too many to list in one slide, include model resolution, groundwater, BMPs, land-use assessment and land-use change. Specific Topics in this presentation: Improving the agricultural model: mass-balance, manure nutrients, fertilizer rates Improving the Urban model: mass-balance, fertilizer, urban growth Improving BMPs: efficiencies, extreme weather, retirement and physical simulation

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Mass-Balance Approach This phrase appeared throughout the discussion on the issues of phase 5 enhancements. Valid for not only Agricultural, but also Urban and forested lands. Involves accounting for inputs, retention, removals, and losses of nutrients Fertilizer (Ag, Urban) Atmospheric (Ag, Urban, Forest) Legume (Ag only) Manure (Ag only) Bio-solids (Ag only) Allow for transport from one segment to the next

Agricultural Model: Components 16 Ag Land-uses: Vary by tillage, crop type, fertilizer type, fertilizer rate (nutrient management), presence of livestock Uses the AGCHEM module of HSPF Yield-based algorithm Maximum uptake / return to soil “Composite Crop” – single crop per year Application timing, amounts based on crop type, fertilizer type Uptake, applications, are “quasi-monthly” (trapezoidal)

Agricultural Model: Strategies Realistically Model Agricultural Lands: Continuous Simulation Long-term soil nutrient balances Crop Uptake reflects real world data Infiltration rates vary by land-use/tillage Realistically simulate Nutrient Management Application rates and timing vary by land-use, county, year, climate/cultural region, nutrient source, and composite crop component Account for volatilization/re-deposition of agricultural ammonia Land-river segment manure generated, and manure and fertilizer application timing and rates used in new atmospheric deposition model

Agricultural Model: Strategies Manure is applied in county in which it is generated, unless we are told otherwise Fertilizer uses bay-wide control volume. Nutrient Management rates were a recurring concern in TSWG minutes Effective rates shown by fertilizer sales analysis Bonus: Effects of P-testing and economics appear in this analysis

Agricultural Model: Composite Crop

Agricultural Model: N:P Link Manure pre-processor designed with “Virtual Storage Bins” Manure stored in bin, aggregate N:P ratio exists. Manure is distributed based on either N or P as limiting nutrient If either nutrient is below crop application rate, inorganic fertilizer is supplemented Limiting Nutrient may be varied by land-use, county, year

Agricultural Model: N:P Link, cont. Implications of maintaining the N:P link, coupled with continuous model soil simulation: Model shows over-application of P under an N-based plan in counties with excess manure. Long-term over application of P can result in increasing losses of modeled dissolved P. Will compare with soil test results and latest research on dissolved P losses and soil test P.

Agricultural Model: N:P Link, cont. Lower Eastern Shore Phosphorus Simulation, model calibration version 1.0 EOS EOS

BMP Model: Areas of Interest Major Areas of Concern: Are efficiencies over-estimated? Can we simulate extreme weather effects? Do we capture BMP lifetime properly? Can we model BMP seasonality? Cover crops is primary here Do we capture BMP retirement? Do we get phased implementation? Is nutrient management, in all its guises, done properly? This begs the question: Can we move beyond efficiencies?

BMP Model: The Grand Inquisition University of MD BMP contract – In Progress Revisit efficiencies Extensive lit. review Consult with experts around the watershed Investigate Extreme weather effects Which BMPs are affected? What are the circumstances? Ageing effects How do BMPs age Do different BMPs age differently

BMP Model: Simulation Types Efficiency: edge of field output is multiplied by some reduction factor before delivery to the stream. Land Use Change: Acres are converted from one modeled land use to another to represent the BMP. Altered Inputs: Change amount, timing, or type of nutrient inputs. Model is remarkably sensitive to timing. Physical simulation: alter physical characteristics such as roughness, infiltration, or other (really, more a sub-category of land-use change). Advanced Physical Sim.: Route runoff from upland land-uses through a buffer strip land-use (permissible in HSPF 12) Note: Physical simulation, Altered Inputs or Lu Change are preferable if your land use is understood, fits into model framework, and is well calibrated

BMP Model: Examples Forest Buffers, efficiency + LU Change – 1 acre treats 4 acres of upland runoff, reducing N (22-75%), P (42-68%), and S(42-68%). Land converted to forest. Continuous no-till, LU Change + Efficiency: High till goes to low-till – low-till land use has a higher infiltration, roughness, lower nutrient yield. Nutrient management, Altered Inputs – NM land use is the same as as parent land use (including soil reactions), but lower application rate. Drainage Control, Physical Simulation/effic.: Could alter the Reach output curve (FTABLE) to mimic detention, nitrogen transformations. Big question: what are relative contributions of de-nitrification and enhanced nutrient uptake efficiency. Currently, it is an efficiency. Efficiency has been arrived at by AgNRWG, but research scale and actual watershed implimentations are entirely different

BMP Model: The Faces of NM A physical simulation of land-use change AGCHEM crop simulation, coupled with greater model resolution, and varying application rates allows strong NM simulation Enhanced Nutrient Management now can be modeled as physical BMP also (reducing rates)

Traditional Maximum Yield Based Fertilization In order to achieve maximum yield with a uniform application rate farmers must apply at the rate of the highest yielding areas of the field, plus a margin of safety. Results in over-fertilization of less-productive areas in the field. Ex: Field has max need of 80 lbs-N/ac, application rate = 100 lbs-N/ac Residual N 100 lbs-N / ac 100 lbs / ac 70 lbs / ac 50 lbs / ac

Nutrient Management Aimed at Long Term Average Yield Aims for “average achievable yield under favorable conditions”. (Ex: best 3 of 5, best 4 of 7 yields) Reducing application rate prevents some over-fertilizing in less productive areas, reduces margin of safety on highest yielding areas. Relies on residual N from non-max years, to maintain high yields Enhanced NM is just a more extreme case of this. Ex: Field has max need of 80 lbs-N/ac, rate = 80 lbs-N/ac, uptake may be as high as 80 lbs/ac Residual N 80 lbs-N / ac

Precision Agriculture Based on Max. Yield variations Maps yield areas in fields in order to account for variations in soil productivity. Minimizes over-fertilization of low-productivity areas without limiting yield in high productivity areas. Ex: Field has max need of 80 lbs-N/ac, application rate = 80 lbs-N/ac, uptake may be as high as 80 lbs/ac. Can we simulate it?? Residual N

Precision Agriculture + Nutrient Management – does this happen? Maps yield areas in fields in order to account for variations in soil productivity, applies at nutrient management rates. Minimizes over-fertilization of low-productivity areas without limiting yield in high productivity areas. Ex: Field has max need of 80 lbs-N/ac, application rate = 75 lbs-N/ac, uptake may be as high as 80 lbs/ac. Can we simulate it?? Residual N

BMP Model: Retirement/Aging Recommendatoinsfor 5% of retired lands to contain BMPs, not yet implemented, however: Some partners are reporting retirement when they know of it NEIEN will include age of BMP in data collected UMD study may shed light on the aging process, and how to cope with it

Urban Model: Improvements Needed to use the same mass-balance approach on urban lands if possible. Need to account for impervious and pervious land uses, very different behavior Urban BMP physical simulations a hard nut to crack (listed as questionable on the GRID)

Urban Model: Pervious Area/EOS Fertilizer sales data is at county level Couldn’t use it at this level just yet, went with a bay-wide control volume, similar to ag. Recent research indicates that urban fert rates are 8-10 lbs-N/acre, our mass balance agrees. Fertilization of new/recent construction is most significant source of applications Made assumption of 80% retention (better than ag) of fertilizer and atmospheric inputs Allowed for variation driven by atmospheric deposition

Urban Model: Impervious EOS Urban Impervious surfaces a little more difficult to characterize Inputs: Atmospheric Deposition (from Atmospheric model) Miscellaneous Direct Automobile Deposition (difficult to estimate) Other Sources (animals, trash spillage, etc.) Outputs: Little to no attenuation of N and P is expected to occur on impervious surfaces Outputs are known from urban studies, generally based on Event Mean Concentration (EMC) Mass Balance: E = m + A ; A = atmospheric, m = miscellaneous

Urban Model: Estimating M Quantify the misc. on impervious surfaces from EMC Assumptions: Rainfall = runoff on impervious surface = 40” / ac-year NURP/NSDQ Average EMC on highly impervious (>80%) 2.2 mg/L This EMC represents mean value in watershed EMCs already include any attenuation Assume that “m” is constant, and the only variable is atmospheric Acreage of impervious will be the greatest factor in loading 12.74 lb-N/ac mean atmospheric deposition m = EMC*Runoff - A Calculations: