reducing nutrients from non-point sources
DESCRIPTION
Reducing Nutrients from Non-Point Sources. Matthew Helmers Dean’s Professor, College of Ag. & Life Sciences Professor, Dept. of Ag. and Biosystems Eng. Iowa State University. Situation. Increasing concern for local and regional waters Substantial demand for agricultural products - PowerPoint PPT PresentationTRANSCRIPT
Department of Agricultural and Biosystems Engineering
Reducing Nutrients from Non-Point Sources
Matthew HelmersDean’s Professor, College of Ag. & Life Sciences
Professor, Dept. of Ag. and Biosystems Eng.Iowa State University
Department of Agricultural and Biosystems Engineering
Situation• Increasing concern for local and
regional waters• Substantial demand for agricultural
products• Hypoxia Action Plan in 2008 called for
development and implementation of comprehensive N and P reduction strategies for states in the Mississippi/Atchafalaya River Basin
Department of Agricultural and Biosystems Engineering
Gulf of Mexico Hypoxia Goals
Hypoxia Action Plan Goal: Reduce the size of the zone to 5,000 km2 by 2015
EPA-SAB Recommendations: Reduce Total Riverine Nitrogen and Phosphorus Loads by 45%
Department of Agricultural and Biosystems Engineering
Can we achieve the nutrient reduction goals for Gulf of Mexico Hypoxia?
• Not simple • Not as simple as just fine-tuning
nutrient management• Not impossible
Department of Agricultural and Biosystems Engineering
Approach1. Establish baseline – existing conditions2. Conduct an extensive literature review to
assess potential performance of practices• Outside peer review of science team documents
(practice performance and baseline conditions)3. Estimate potential load reductions of
implementing nutrient reduction practices (scenarios)• “Full implementation” and “Combined” scenarios
4. Estimate cost of implementation and cost per pound of nitrogen and phosphorus reduction
Nitrate-N Reduction Practices
Practice % Nitrate-N Reduction [Average (Std. Dev.)]
% Corn Yield Change
Nitrogen Management
Timing (Fall to spring) 6 (25) 4 (16)Nitrogen Application Rate (Reduce
rate to MRTN) 10 -1
Nitrification Inhibitor (nitrapyrin) 9 (19) 6 (22)
Cover Crops (Rye) 31 (29) -6 (7)
Land Use
Perennial – Pasture/Land retirement 85 (9)
Perennial – Energy Crops 72 (23)
Extended Rotations 42 (12) 7 (7)
Edge-of-Field
Controlled Drainage 33 (32)*
Shallow Drainage 32 (15)*
Wetlands 52
Bioreactors 43 (21)
Buffers 91 (20)**
*Load reduction not concentration reduction**Concentration reduction of that water interacts with active zone below the buffer
Phosphorus Reduction Practices
Practice% Phosphorus-P
Reduction [Average (Std. Dev.)]
% Corn Yield Change
Phosphorus Management
Producer does not apply phosphorus until STP drops
to optimal level17 (40) 0
No-till (70% residue) vs. conventional tillage (30%
residue)90 (17) -6 (8)
Cover Crops (Rye) 29 (37) -6 (7)
Land UsePerennial – Land retirement 75 (-)
Pasture 59 (42)
Edge-of-FieldBuffers 58 (32)
Terraces 77 (19)
Assessment did not include stream bed and bank contributions although recognized as significant
Nutrient Load Reduction Scenarios
Nitrate-N Reduction
Cost of N Reduction
Phosphorus Reduction
Cost of P Reduction
Total Equal Annualized
Cost
Practice/Scenario% (from
baseline)($/lb)
% (from baseline)
($/lb) (million $/yr)
Reducing nitrogen application rate from background to the MRTN 133 lb
N/ac on CB and to 190 lb N/ac on CC
9 -0.58 -32
From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus
Nutrient Load Reduction Scenarios
Nitrate-N Reduction
Cost of N Reduction
Phosphorus Reduction
Cost of P Reduction
Total Equal Annualized
Cost
Practice/Scenario% (from
baseline)($/lb)
% (from baseline)
($/lb) (million $/yr)
Cover crops (rye) on ALL CS and CC acres
28 5.96 50 60 1,025
From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus
Nutrient Load Reduction Scenarios
Nitrate-N Reduction
Cost of N Reduction
Phosphorus Reduction
Cost of P Reduction
Total Equal Annualized
Cost
Practice/Scenario% (from
baseline)($/lb)
% (from baseline)
($/lb) (million $/yr)
Install Wetlands to treat 45% of the ag acres
22 1.38 191
From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus
1 km
Targeted Wetland Restoration
Iowa Conservation Reserve Enhancement Program (CREP)
0 0 .1 0 .2 0 .3 0 .4A v erag e h y d rau lic lo ad in g ra te (m d ay -1 )
0
2 0
4 0
6 0
8 0
1 0 0P
erce
nt n
itrat
e m
ass
rem
oved
M o d e le d n itra te re m o v al
2 0 0 4 -2 0 1 1 o b se rv ed w e tla n d s
2 0 1 2 o b se rv ed w e tla nd s
Source: W. Crumpton
Nutrient Load Reduction Scenarios
Nitrate-N Reduction
Cost of N Reduction
Phosphorus Reduction
Cost of P Reduction
Total Equal Annualized
Cost
Practice/Scenario% (from
baseline)($/lb)
% (from baseline)
($/lb) (million $/yr)
Install Denitrification Bioreactors on all tile drained acres
18 0.92 101
From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus
Nutrient Load Reduction Scenarios
Nitrate-N Reduction
Cost of N Reduction
Phosphorus Reduction
Cost of P Reduction
Total Equal Annualized
Cost
Practice/Scenario% (from
baseline)($/lb)
% (from baseline)
($/lb) (million $/yr)
Install Buffers on all applicable lands (30 ft. on each side of stream)
7 1.91 18 14 88
From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction on Nitrogen and 29% reduction on Phosphorus
100% Crop 100% Prairie10% Prairie - 90% Crop
Overall Comparison of Nitrate-N Practices
Nitrate-N Reduction
Cost of N Reduction
Other Benefits
(Ecosystem Services)
Practice/Scenario% (from
baseline)($/lb)
Reducing nitrogen application rate from background to the MRTN
9 -0.58
Cover crops (rye) on ALL CS and CC acres 28 5.96 ++
Install Wetlands to treat 45% of the ag acres 22 1.38 ++
Install Denitrification Bioreactors on all tile drained acres
18 0.92
Install Buffers on all applicable lands 7 1.91 ++
Installing Controlled Drainage on all applicable acres
2 1.29
Perennial crops (energy crops) on ~6.5 million acres
18 21.46 ++
Overall Comparison of Phosphorus Practices
PReduction
Cost of P Reduction
Other Benefits
(Ecosystem Services)
Practice/Scenario% (from
baseline)($/lb)
Cover crops (rye) on ALL CS and CC acres 50 60 ++
Convert all tillage to no-till 39 14 ++
P rate reduction in MLRA’s that have high to very high soil test P
7 -110
Establish streamside buffers (35ft) on all crop land
18 14 ++
Perennial crops (energy crops) equal to pasture/hay acreage from 1987
29 238 ++
Pasture and Land Retirement to equal acreage of Pasture/Hay and CRP from 1987
9 120 ++
Example: Combination Scenarios that Achieve N and P Goal From Non-Point Sources
From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction on Nitrogen and 29% reduction on Phosphorus
Nitrate-N Reduction
Phosphorus Reduction
Initial Investment
Total Equal Annualized
Cost
Statewide Average EAC
Costs
Practice/Scenario% (from
baseline)% (from
baseline)(million $)
(million $/yr)
($/acre)
MRTN Rate, 60% Acreage with Cover Crop, 27% of ag land treated with wetland and 60% of drained land has bioreactor
42 30 3,218 756 36
MRTN Rate, 95% of acreage in Cover Crops, 34% of ag land in heavily tile drained land treated with wetland, and 5% land retirement
42 50 1,222 1,214 58
Department of Agricultural and Biosystems Engineering
One Farm What Can We Do?
Department of Agricultural and Biosystems Engineering
One Location – Many Possibilities
Department of Agricultural and Biosystems Engineering
Existing Conditions • All row crop land – 1160 acres• Average slope 2.5%• MLRA average N application rate is
estimated to be 184 lb-N/acre to corn following beans
• Primarily conventional till
Department of Agricultural and Biosystems Engineering
What Should We Do?
Department of Agricultural and Biosystems Engineering
Nitrate-N Reduction – What Should We Do?
• Nitrogen Management (N rate)
• Cover crops• Bioreactors• Wetlands
Nitrogen Rate – MLRA 107a
Department of Agricultural and Biosystems Engineering
What Should We Do?
Potential BioreactorLocations
Department of Agricultural and Biosystems Engineering
What Should We Do?
Potential WetlandLocation
Department of Agricultural and Biosystems Engineering
Nitrate-N Conditions
Condition – Practice
Nitrate-N Concentration
(mg/L)
Nitrate-N Load (lb-N/acre)
% Reduction from Baseline
Other Benefits
Existing 14.3 23.8
Reduce N rate to MRTN (184 to 133 lb-N/acre)
10 16.8 29
Cover Crops on 50% of Acres
12 20 16 Soil quality
Bioreactor for 25% acres 13 22.3 6.3
Wetland to Treat 1160 Acres
6.8 11.4 52 Aesthetics, habitat, flow
Department of Agricultural and Biosystems Engineering
Nitrate-N Combined Scenarios
Condition – Practice
Nitrate-N Concentration
(mg/L)
Nitrate-N Load
(lb-N/acre)
% Reduction from Baseline
Other Benefits
Existing 14.3 23.8
Reduce N rate to MRTN 10 16.8 29
Cover Crops on 50% of Acres with MRTN
8.6 14.3 40 Soil quality
Bioreactor for 25% acres with MRTN 9.4 15.8 34
Wetland to Treat 1160 Acres with MRTN and Cover Crops on 50% of Acres
4.1 6.8 71
Aesthetics, habitat, flow,
and soil quality
Department of Agricultural and Biosystems Engineering
Phosphorus – What Should We Do?
• Reduced tillage• Cover Crops• Buffers
Department of Agricultural and Biosystems Engineering
Estimated Sediment and Phosphorus Loss
Conv.
Till
Strip
Till
No-till
No-till
w/C
C
Conv.
Till w
/Buff
er
Strip
Till w
/Buff
er
No-till
w/B
uffer
No-till
w/C
C and
Buff
er
Se
dim
ent
Lo
ss (
tons
/acr
e)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Pho
spho
rus
Lo
ss (
lb/a
cre
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Sediment LossTotal Phosphorus Loss
Department of Agricultural and Biosystems Engineering
Potential Prairie Strips Location
Department of Agricultural and Biosystems Engineering
Example of Prairie Strips Design
Department of Agricultural and Biosystems Engineering
Education of All Stakeholders will be Key
Department of Agricultural and Biosystems Engineering
Summary• To achieve goals will require a
combination of practices – conservation systems approach
• N versus P may require different practices
• Multiple benefits and costs of practices need to be considered
• Targeting of practice placement will be critical (Precision Conservation)
Department of Agricultural and Biosystems Engineering