1
David BurtonDepartment of Plant, Food, and Environment
4R Nitrogen Management to Increase N Use Efficiency and Reduce N Losses
The Objective of N FertilizationSoil Fertility – The objective in an N fertilization program is to realize the economically optimum yield.
The Objective of N FertilizationSoil Fertility – The objective in an N fertilization program is to realize the economically optimum yield.
Nutrient Management – The objective in an N fertilization program is to not only realize the economically optimum yield but to also minimize environmental impacts.
To improve nutrient management the fertilizer industry has developed the framework of 4R management
IPNI, 2015
The Objective of N FertilizationSoil Fertility – The objective in an N fertilization program is to realize the economically optimum yield.
Nutrient Management – The objective in an N fertilization program is to not only realize the economically optimum yield but to also minimize environmental impacts.
Soil Health Management – The objective in an N fertilization program is to not only realize the economically optimum yield but to also minimize environmental impacts and sustain the resource.
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But, all is not well…
How did we get here?
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The Plough
8
The plough revolutionized agriculture! It provided a uniform seed bed, controlled weeds and released nutrients for plant growth.
But ploughing the soil degrades soil organic matter releasing nutrients to support plant growth…
• Organic matter is more than just nutrients• As with any stock, it can be depleated.
Fertilization
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1858 - Justus von Liebig - Plants could grow on minerals alone1908 - Fritz Haber and Carl Bosch discovered how to make reactive nitrogen from the air… the basis of N fertilizer
Together they gave rise to the green revolution
But you can have too much of a good thing… humanity has doubled the reactive nitrogen on the planet!
National Geographic, 2013
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Atlantic Soil Health Lab
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Cropping System and Nitrogen Mineralization
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To improve nutrient management the fertilizer industry has developed the framework of 4R management
IPNI, 2015
4R Frame work builds on science and offers practical solutions
IPNI, 2015
Right Source• Balanced supply of nutrients and recognize synergies• Use of sources that are (or will become) plant available• Ammonium (NH4
+) based sources are less likely to be lost than nitrate (NO3
-)• Use of enhanced efficiency fertilizer products
• Urease and nitrification inhibitors• Coated N sources
• Organic N sources – animal manures, biosolids, composts
Right Time• Attempt to synchronize N availability with plant N
demand
• Applying all at or before planting increases risk of N loss
• Can improve synchrony of N supply by• Delaying nitrification – NH4
+ less likely to be lost than NO3
-
• Using urease or nitrification inhibitors• Banding of N fertilizer to inhibit nitrification• Coated products• Application of N to cold soils delays
nitrification• Split applications of N
• Side-dress applications• Foliar applications & fertigation
Right Place• Right place refers to placement of fertilizer
with respect to the seed• Sub-surface placement to reduce NH3
losses• Sub-surface placement to reduce N2O
loss (does not always work)• Banding to reduce nitrification and delay
NO3- production to reduce leaching and
N2O loss• Also placement within the landscape
• Precision farming – place the N according to yield expectations
• Avoid areas of high risk of NO3- loss
and/or N2O emissionsIPNI, 2015
Right Rate• Need to emphasize realistic yield goals and resultant plant nutrient
demand• Use the other R’s to predict and improve nutrient use efficiency• Assess soil nitrogen supply• Credit manure and legume N sources• N rate influences plant yield, economic return and environmental impact
differently
Plant Response to N Application
Fertilizer N Application (kg N/ha)
Economic Return of N fertilization
Environmental N Impacts of N fertilization
Right Rate• Need to emphasize realistic yield goals and nutrient use efficiency• One of the tools to help us assess nutrient use efficiency is calculating a
partial nutrient balance
Partial Nitrogen Balance for CornYield Goal(8.3 tonnes)
N Fertilizer(kg N/ha) 131
Crop N Removal(kg N/ha) 94
Partial N Balance 37
Fertilizer N UseEfficiency (%) 72%
Partial Nitrogen Balance for CornYield Goal(8.3 tonnes)
N Fertilizer(kg N/ha) 131
Crop N Removal(kg N/ha) 94
Partial N Balance 37
Fertilizer N UseEfficiency (%) 72%
Yield Goal(45 tonnes)
N Fertilizer(kg N/ha) + 131
Soil Nitrogen Supply (kg N/ha) + 90
Crop N Removal(kg N/ha) - 94
Residue and Root N return(kg N/ha) - 60
Partial N Balance 67
N Use Efficiency (%) 43%
Partial Nitrogen Balance for PotatoYield Goal(45 tonnes)
N Fertilizer(kg N/ha) 180
Crop N Removal(kg N/ha) 144
Partial N Balance 36
Fertilizer N UseEfficiency (%) 80%
Partial Nitrogen Balance for PotatoYield Goal(45 tonnes)
N Fertilizer(kg N/ha) 180
Crop N Removal(kg N/ha) 144
Partial N Balance 36
Fertilizer N UseEfficiency (%) 80%
Yield Goal(45 tonnes)
N Fertilizer(kg N/ha) + 180
Soil Nitrogen Supply (kg N/ha) + 65
Crop N Removal(kg N/ha) - 144
Residue and Root N return(kg N/ha) - 40
Partial N Balance 61
N Use Efficiency (%) 59%
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David BurtonDepartment of Plant, Food, and Environment
Tools to Improve Nitrogen Management in Atlantic Canada
The Importance of nitrogen management in Prince Edward Island• Potato production contributes 10% of
PEI’s GDP• Province 100% dependent on groundwater
• Concern regarding nitrate impacts• PEI also has a significant shellfish industry
• Concern regarding N impacts on estuaries
• Need for improved N use efficiency in potato production systems to meet economic and environmental goals
• A NERP could contribute to improving N use efficiency reducing N2O emissions and nitrate leaching
In collaboration with…
• AAFC – Bernie Zebarth, Judith Nyiraneza• PEI Department of Agriculture – Kyra Stiles• PEI Potato Board – Ryan Barrett• Fertilizer Canada & Genesis Crop Systems – Steve Watts• Kensington North and East Prince Watershed groups
Tools to increase N use efficiency in Atlantic CanadaNeed to consider all sources of N.
Therefore we need tools to measure all sources of N: • soil N supply (SNS),• climate impacts on N
mineralization• potential for N loss
• Nitrate Exposure• Residual Soil N
Residual Soil Nitrate
SNS = Soil Nitrogen SupplyNo = N Mineralization Potential
Biological N SupplyEn
viro
nmen
tal C
ontr
ols
Direct N2O emissions
Indirect N2O emissions
Manure N
Crop Yield
Nitrate Leaching
4RFertilizer
Management
Source
Timing
Rate
Placement
Soil Mineral N Plant Available N
Crop Residue
NSoil
Organic N
Farm Inputs
Outputs
Nitrate Exposure
No & Nitrogen Mineralization
Function
SNS Test
Water Function
Soil and Climatic Controls
Soil Properties
Temperature Function
Measuring soil nitrogen supply
Manure N
Soil Mineral N Plant Available N
Crop Residue
N
Soil Organic
N
SNS Test
In Atlantic Canada high potential for over-winter nitrate loss makes the mineralization of N during the growing season an important N source
We do not currently measure the N supplying capacity of the soil
Can a simple, practical test be developed and implemented in regional soil test labs?
Can we measure Soil N Supply?• Soil Nitrogen Supply (SNS) test
NH4+ + NO3
-
Residual Soil Mineral N
NH4+ + NO3
-
BiologicalN Flush
2 weekaerobic
incubation
Dilute Salt Solution
(0.01 M CaCl2)
Dilute Salt Solution
(0.01 M CaCl2)
Air Dry Soil
Is there significant variation in soil N supply
in PEI soils?
Soil mineral N content changes from fall to spring
Biological N flush is more constant from fall to spring
Spatial variation in biological N flush
Soil Properties (Total N and N flush) and climate data (air temperature and precipitation) can be used to predict N mineralization
Manure N
Temperature Function
Soil Mineral N Plant Available N
Crop Residue
N
Soil Organic
N
No & Nitrogen Mineralization
Function
SNS Test
Soil PropertiesWater Function
Leads to a better understanding the impact of soil properties and climate on soil N supply
Considerable farm-to-farm variation in estimated N mineralization
Measures of N supply (kg N ha-1) by region
• Significant range in values between farms... 4R opportunity!• N mineralized over 130 days (Nmin) ranged from 31 – 111 kg N ha-1
Assuming 30 cm depth
Region BiologicalN Flush
No Nmin1
kg N ha-1Western 16.4 140 ab 75 ab
Central West 18.5 152 a 77 a
Central East 19.5 142 ab 79 ab
East 15.1 130 b 68 b
Estimated nitrogen mineralized over 130 days
Estimated nitrogen mineralized over 130 days
Measuring the Potential for N Loss
•Need a means of practicallymeasuring the potential for N loss
• N2O emissions• Nitrate leaching
•Can assess how well management is doing in reducing nitrate accumulation
• Feedback to producer• Documentation of success of
mitigation strategies
Residual Soil Nitrate
Direct N2O emissions
Indirect N2O emissions
Crop Yield
Nitrate Leaching
Soil Mineral N Plant Available N
Outputs
Nitrate Exposure
Agri-Environmental Indicators Residual Soil Nitrogen
Partial Nitrogen Balance for PotatoYield Goal(45 tonnes)
N Fertilizer(kg N/ha) 180
Crop N Removal(kg N/ha) 144
Residual Soil N 36
Fertilizer N UseEfficiency (%) 80%
Yield Goal(45 tonnes)
N Fertilizer(kg N/ha) + 180
Soil Nitrogen Supply (kg N/ha) + 65
Crop N Removal(kg N/ha) - 144
Residue and Root N return(kg N/ha) - 40
Residual Soil N 61
N Use Efficiency (%) 59%
Nitrate Exposure• Nitrate Exposure (NE) is a temporally integrated measure of the exposure
of the soil microbial community to NO3-
• An extensive variable• May be an “emergent property”• It measures the exposure of plant to
nitrate and the potential for loss to the environment
NE [NO3]i *
di1 di1
2
i1
n
Nitrate Exposure
time
Nitrate Exposure and N2O Emissions Atlantic Canadian Cropping Systems
R² = 0.73
R² = 0.87R² = 0.88
R² = 0.85
R² = 0.99
R² = 0.19
R² = 0.29
0
2
4
6
8
10
12
0 5 10 15 20 25
Cumulative N2O
Emissions
(kg N/ha)
Nitrate Exposure (gN d/kg soil)
Potato ‐ 2002 ‐ Burton et al. 2008Potato ‐ 2003 ‐ Burton et al. 2008Barley ‐ 2003 ‐ Zebarth et al. 2008aBarley ‐ 2004 ‐ Zebarth et al. 2008aBarley ‐ 2005 ‐ Zebarth et al. 2008aCorn ‐ 2004 ‐ Zebarth et al. 2008bCorn ‐ 2005 ‐ Zebarth et al. 2008b
Nitrate Exposure and N2O EmissionsNorth American Cropping Systems
Tools to increase N use efficiency in Atlantic Canada
Need tools to: •measure soil N supply (SNS),
•predict climate impacts on N mineralization,
•measure potential for N losses• Nitrate exposure• Residual soil nitrogen
• Recognize and value increased NUE
Residual Soil Nitrate
SNS = Soil Nitrogen SupplyNo = N Mineralization Potential
Biological N SupplyEn
viro
nmen
tal C
ontr
ols
Direct N2O emissions
Indirect N2O emissions
Manure N
Crop Yield
Nitrate Leaching
4RFertilizer
Management
Source
Timing
Rate
Placement
Soil Mineral N Plant Available N
Crop Residue
NSoil
Organic N
Farm Inputs
Outputs
Nitrate Exposure
No & Nitrogen Mineralization
Function
SNS Test
Water Function
Soil and Climatic Controls
Soil Properties
Temperature Function
Current 4R Evaluations in PEI• 4R evaluations in side-by-side trials in producer fields
• In collaboration with 4R Island• Measuring GHG Emissions, soil N supply and nitrate exposure
• Evaluation of foliar urea as a more effective means of supplying in season N application
• Reduce spring N application• Apply additional N in season as part of pesticide application as needed
Role of a Nitrous oxide Emissions Reduction Protocol (NERP)• 4R Nutrient Stewardship provides climate-smart agricultural practices that
reduce N20 emissions for farmers• A NERP values and documents these practices• Encourages adoption of 4Rs to increase N use efficiency and meet
environmental objectives• Provide incentive for producers to adopt and monitor the success of 4R
strategies• Emphasizes the importance of resource monitoring and maintenance =
sustainability
This research has been supported by...