2017 SWCS Annual Conference July 30-August 2, 2017 Monona Terrace Convention Center

1. Agriculture and
Agri-Food Canada
Agriculture et
Agroalimentaire Canada
J.Y. Yang and C.F. Drury
Harrow Research and Development Centre
Agriculture and Agri-Food Canada
Harrow Ontario, N0R 1G0, Canada
Developing a Reactive Nitrogen
Model for Canadian Agricultural
Land
Canada
The 72th SWCS International Annual Conference, Madison, Wisconsin,
July 30-Aug 2, 2017

2. Agriculture and Agri-Food Canada
Agriculture and
Agri-Food Canada
Agriculture et
Agroalimentaire Canada
Canada
Harrow Research and Development Centre (42.03N;82.92W)

3. 1 Introduction
2 Reactive N model
N inputs
N outputs
Data sources
Scale-up Methodology
3 Results and discussion
4 Summary
Table of contents

4. Canada has ≈ 60 million ha of farmland, about 1.6
Mt fertilizer N is used, and 1.3 Mt biological N
fixation by legumes, and 1.1 Mt manure N is
produced each year (2000 - 2011).
About 30-60% of N input was lost via
- Greenhouse gas (N2O, NO)
- Ammonia emission (NH3)
- N leaching and runoff (NO3)
Introduction

5. Reactive N model
Reactive N model and assumption
At given region, N input = N output in a yearly cycle,
assuming soil organic N is stable.
Reactive N model is the updated version of the
Canadian Agricultural Nitrogen Budget (CANB) v4.0
model
The CANB v4.0 model was used to estimate two Agro-
Environmental Indicators at Canadian Farmland 1981-
2011
Reference: Yang et al., 2013. Ecological Modelling 267, 26-38

6. N food = N removal by food and fiber crops by humans
N feed = N removal by animal feed
N loss = N2O + NH3 + NO3 (leaching + runoff)
RSN = Residual soil Inorganic Nitrogen present in the soil
after harvest
N input = N fert + N fix + N depo + Nfix_min
N output = N food + N feed + N loss + RSN
N fert = N input from fertilizer
N fix = Biological N fixation and residual N mineralization
N depo = Dry and wet N deposition from atmosphere
N fix_min = N mineralization from legume crop residue
Reactive N model

7. Reactive N model
N feed = N meat + MN total
N manure = MN inorganic + MN organic + MN_NH3 + MN_N2O
Internal cycles of manure N

8. Fig. 3 Canadian Ecoregion map (1:1M)
Canadian
Farmland has
Ecozone 8
Ecoregion 68
Ecodistrict 377
SLC 3300
Province10
Base calculation unit: Soil Landscapes of Canada
(SLC) 1:1 M soil polygon
Nested in ecodistrict, ecoregion, ecozone
The CANB-Reactive N model

9. National
Soil – Great Group (28)
Province (10)
Eco-Zone (8)
Eco-Region (68)
Eco-District (377)
Soil Polygon (3300, 1:1M)
1981 – 2011 - Current study at SLC
20161981, 1982, ……, 2011
2016 – Census data will be available in 2017
Output and scale-up methodology

10. Data sources
At Soil Landscape of Canada scale
At Eco-district scale
At Provincial scale
At National (Canadian) scale
At Soil Great Group scale

11. Examples of N data
at SLC scale
Fertilizer N
Biological N fixation
Crop yields

12. Fertilizer N
recommendation
24 crop types
28 soil types
1981 to 2011
Inputs of
CANB model
Adjust fertilizer N rate to equal the total provincial N sale
Calculate total fertilizer N
application
Crop area
27 crop types
3200 SLCs
1981 to 2011
Fertilizer N sales
10 province
1981 to 2011
)p(total_Nrcmd
)p(Nsales
)j,i(Nrcmd)j,i(Nfert raterate 
Fertilizer N
Yang et al., 2011. Can J Soil Sci. 91: 107-122


24
1
),(),()(_
j
rate jiCropAreajiNfertiapplyNfert

13. Crop yield data
For 24 COA crops
At 3200 SLCs
1981 to 2006
Inputs of
CANB model
N fixation rate
adjustment
N fixation
calculation
Crop area data
For 24 COA crops
At 3200 SLCs
1981 to 2006
Rate parameters
Mean N fixation rate
Shoot root ratio
Harvest Index


24
1
),(),()(
j
ratetotal jiAreajiNfixiNfix
)(
),(
)(),(
jyield
jiyield
jNfixjiNfix
mean
meanrate 
Biological N fixation
Yang et al., 2010. Agri. Ecosyst. Environ 137, 192-201

14. Statics Canada
Annual yield
At 65 Canadian
Agricultural Region
12 COA crops
At 65 CAR scale
Re-class
Downscale to
SLC
Statics Canada
Annual yield at 10
province
71crop+veg+fruit
21 COA crops
At 10 province
Re-class
Missing value
24 COA crop yield data
At 3200 SLC (1981 to 2006)
Yield from literature
Alfalfa
Improved pasture
Unimproved pasture
Missing value
3 COA crops
At 10 Province
Crop yield & resolution
Missing
values?

15. Result and discussions
N inputs & outputs at various scales
NO3 lost map
NO3 lost trend (1981-2011)
Reactive N balance in 2011

16. N input at Canada
kg-N per farmland area

17. Total N output at Canada
N loss N food, N feed & RSN

18. N outputs in kg N/ha farmland
kg N per farmland area

19. N input at a provincial scale (kg N/ha)

20. N output at a provincial scale (kg N/ha)

21. NO3 loss map across Canadian Farmland
NO3 leaching in 1981

22. NO3 loss map across Canadian Farmland
NO3 leaching in 2011

23. NO3 loss (kg N ha-1 farmland)
1981
1991
2001
2011
Western Canada Eastern Canada

24. NO3 loss at a provincial scale
Total NO3 loss
NO3 loss per
farmland area

25. NO3 loss trend
Average NO3 loss increased from 1981 to 2001, then
declined linearly from 2001-2011

26. Reactive N balance in 2011
Reactive N balance (1000 Tonne N)
N input = Nfert + Nfix + Ndepo + Nfix_min = 2009 + 1296 + 306 + 340 = 3951
N output = Nfood + Nfeed + Nloss + Nsoil = 1735 + 1290 + 416 + 510 = 3951
Internal cycle (1000 Tonne N)
MN total = MN inorganic + MN_NH3 + MN org = 333 + 227+ 352 = 912
N feed = MN total + N meat = 912 + 378 = 1290
N loss = NO3 + N2O + FN_NH3 = 214 + 72 + 130 = 416

27. Reactive N balance in 2011
N input 3951
N fert 2009
N fix 1296
N depo 306
N fixmin 340
Farmland
Livestock
N loss (water) RSN in soil
NO3 214 51
N input = N output = 3951 (1000 tonne N)
N feed
1290
N food
1735
N Meat
378
N manure
total 912
N loss (N2O + FN-NH3) = 72 + 130 MN_NH3 227
MN org 352
Carryover to next year
MN avail
333

28. Reactive N model estimated the N input and N output at
various scales across Canadian farmland annually
Fertilizer N and N fixation are the main N inputs
N crop removal are the main N outputs
Conclusions
NO3 loss had an increasing trend from 1981-2001 and then
decreased from 2001-2011
N balance showed negative or lower values from 1981-1995
and then became a surplus from 1996 to 2011
Temporal trend

29. Conclusions
NO3 loss was <5 kg N/ha in the Prairie provinces; it ranged
10-40 kg N/ha in Eastern Canada province due to high
precipitation in these provinces
Spatial variation
In 2011 balance, N input = 3951 (1000 tonne N)
N food+N feed = 76.6%
NO3 loss = 5.4%
N2O+NH3 = 5.1%
RSN in soil = 12.9%
Summary of N output and fate in 2011

30. Agriculture and
Agri-Food Canada
Agriculture et
Agroalimentaire Canada
Canada
AAFC Sustainability Metrics
Funding Support
Acknowledgements
Thank you