4r nitrogen management to increase n use efficiency and...

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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.


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


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.

But, all is not well…

How did we get here?

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The Plough

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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)





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


N Use Efficiency (%) 43%

Partial Nitrogen Balance for PotatoYield Goal(45 tonnes)





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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


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



Crop Residue

N

Soil Organic

N


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

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




Crop Yield

Nitrate Leaching


Outputs

Nitrate Exposure

Agri-Environmental Indicators Residual Soil Nitrogen




Residual Soil N 36







Residual Soil N 61


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


SNS = Soil Nitrogen SupplyNo = N Mineralization Potential

Biological N SupplyEn

viro

nmen

tal C

ontr

ols



Manure N

Crop Yield

Nitrate Leaching

4RFertilizer

Management

Source

Timing

Rate

Placement


Crop Residue

NSoil

Organic N

Farm Inputs

Outputs

Nitrate Exposure


Function

SNS Test

Water Function

Soil and Climatic Controls

Soil Properties


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...

4r nitrogen management to increase n use efficiency and...

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