Transcript Slide 1

Greenhouse Gas Emissions from
Crop Production Systems and
Fertilizer Management Effects
C.S. Snyder, T.W. Bruulsema, T.L. Jensen, and P. E. Fixen
Background
• N is essential to the survival of all life
• Over 40% of the people on Earth owe their
existence to the food production made
possible by N fertilizers
• “Human alterations of the N cycle have
caused a variety of environmental and
human health problems ranging from too
little to too much reactive N in the
environment.” (Woods Hole Research Center)
• half the synthetic N fertilizer ever used
has been utilized since 1985
(Howarth,
2005).
http://www.whrc.org/policy/global_nitrogen.htm
IPNI
Dedicated to improved nutrient use
effectiveness and reductions in
environmental footprints: including
GHG emissions
United Nations Educational, Scientific, and Cultural Organization
& Scientific Committee on Problems of the Environment
http://www.icsu-scope.org/unesco/070424%20(w)%20USPB04%20En.pdf
World Population Growth in More
and Less Developed Countries
Billions
10
9
8
7
20% more people in ~ 20 years
6
Less Developed Regions
5
4
Food, fiber, and fuel demands will continue to increase
3
2
…… what will the environmental impacts be?
1
0
1950
More Developed Regions
1970
1990
2010
2030
2050
Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
http://www.prb.org/Publications/GraphicsBank/PopulationTrends.aspx
Best Management Practices to Minimize
Greenhouse Gas Emissions
Associated with Fertilizer Use
IPNI Better Crops
article, Issue 4 of 2007
IPNI Review Paper
Greenhouse Gas Emissions from Cropping Systems
and the Influence of Fertilizer Management
http://www.ipni.net/ppiweb/bcrops.nsf/$webindex/6F2F57CBF1C5209685257394001B2DD0/$file/07-4p16.pdf
Greenhouse Gases (GHGs)
and their sources
• Carbon Dioxide (CO2): fossil fuels (oil, natural gas, and
coal), solid waste, trees and wood products, and also as a result
of other chemical reactions (e.g., manufacture of cement).
• Methane (CH4): production and transport of coal, natural
gas, and oil; livestock and other agricultural practices and by the
decay of organic waste in municipal solid waste landfills.
• Nitrous Oxide (N2O): agricultural and industrial activities,
as well as during combustion of fossil fuels and solid waste.
• Fluorinated Gases: (Hydrofluorocarbons, perfluorocarbons,
and sulfur hexafluoride): synthetic, powerful greenhouse gases
from a variety of industrial processes.
GWP = Global Warming Potential
N O x 296 = CO equivalent
CH x 21 = CO equivalent
– Sometimes used as substitutes for ozone-depleting substances
(i.e., CFCs, HCFCs, and halons). Typically emitted in smaller
2
2 potent GHGs, they are sometimes
quantities,
but because they are
referred to as High Global Warming Potential gases (“High GWP
4
2
gases”).
Sources: U.S. EPA, IPCC 3rd assessment
Agriculture’s Share of GHG
Emissions is Not Increasing
Agriculture
< 10% of total U.S. GHG
Distribution of GHG Emissions
Estimates of N2O Emissions from
Cropland in 1995 (adapted from IFA/FAO, 2001)
Animal
Manure N
Applied
N2O-N emitted
Area
(million
ha)
Fertilizer
N Applied
Canada
46
1.58
0.21
0.067
0.016
24
U.S.
190
11.15
1.58
0.316
0.112
35
1,436
73.48
20.66
3.150
0.735
23
Region
World
1
total
Fertilizer-induced 1
million tonnes
% of total
Estimated using IPCC emission factor of 1%
Recently published reports suggest terrestrial and aquatic N2O-N
emissions may range from 3 to 5% of “new N”
(Crutzen et al., 2008. Atmos. Chem. Phys. 8:389-395)
Consumption of N Sources
100
Oceania
Africa
80
C. Europe
70
E. Europe & C. Asia
60
WANEA
50
NE & SE Asia
40
L. America
30
W. Europe
20
N. America
10
S. Asia
0
E.Asia
25
Other
Am. thiosulfate
20
Aqua ammonia
15
Am. sulfate
Am. nitrate
10
A. ammonia
5
Urea
N Soln.
Year ending June 30
2006
2003
2000
1997
1994
1991
1988
1985
1982
1979
1976
1973
-
Metric tons of N, Millions
U.S. N Source Consumption
30
1970
Short tons of fertilizer, Millions
1970/71
1972/73
1974/75
1976/77
1978/79
1980/81
1982/83
1984/85
1986/87
1988/89
1990/91
1992/93
1994/95
1996/97
1998/99
2000/01
2002/03
2004/05
Million metric tons of N
90
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Anhydrous ammonia
Urea + UAN Sol.
Anhydrous ammonia + urea + UAN
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Year ending June 30
Data source: IFA, AAPFCO & TFI
Range of N2O Emission Among N
Sources can Vary Greatly
• Report 1 (Stehfest &
Bouwman, 2006)
– 0 to 46% of applied N
• Report 2 (Granli &
Bockman, 1994)
– 0 to 7% of applied N
• Report 3 (Eichner, 1990)
– 0 to 7% of applied N
• Report 1
– Median among N
sources ranged from:
0.26 to 1.56 kg of N/ha
N Rates Above Agronomic Optimum
Can Increase Risk of N2O Emission
Nitrogen Use Efficiency
• “…… estimated NUE for cereal
production ranges from 30 to 35%.”
Improving Nitrogen Use Efficiency for Cereal Production
( 1999
Agronomy Journal 91:357-363)
N Recovery and NUE are Affected
by Other Essential Nutrients
Food Yield/
Net GWP
.01
.09
.02
.02
.02
.02
.01
.01
N Loss Consequences Requiring
Management Attention
• Decreased crop production and profitability
– Inefficient land use, reduced performance of other
crop inputs, reduced water use efficiency
• Water resource contamination
– eutrophication: lakes, streams, rivers, estuaries
– groundwater contamination
– coastal water contamination - urea and harmful algal
blooms (neurotoxin poisoning)
• Air pollution
– Ammonia and particulates, nitrous oxide and NOx
(global warming, stratospheric ozone depletion, acid
rain)
Loss of NO3 - N to Water Resources
May Also Impact N2O Emissions
SPARROW - Modeled Estimate of N and P
Discharge in Watersheds of the Mississippi R. Basin
Kg/ha
.01
.01- 0.1
0.1 to 1
1 to 5
5 to 10
>10
Alexander et al., 2008.
Environ. Sci. Technol. 42: 822–830
Nutrient Use Efficiency and Effectiveness:
Indices of Agronomic and Environmental Benefit
Encourage
post-harvest
evaluation of N
effectiveness in
cropping
systems
http://www.ipni.net/ipniweb/portal.nsf/0/d58a3c2deca9d7378525731e006066d5/$FILE/Revised%20NUE%20update.pdf
NUE Term
Calculation Reported Examples
PFP - Partial
Y/F
40 to 80 units of cereal grain per unit of N
(Y-Y0)/F
10 to 30 units of cereal grain per unit of N
UH/F
0 to > 1.0 - depends on native soil fertility
and fertility maintenance objectives
<1 in nutrient deficient systems (fertility improvement)
>1 in nutrient surplus systems (under replacement)
Slightly less than 1 to 1 (system sustainability)
(U-U0)/F
0.1 to 0.3 - proportion of P input recovered first year
0.5 to 0.9 - proportion of P input recovered by crops in
factor productivity
AE - Agronomic
Efficiency
PNB - Partial
nutrient balance
(removal to use
ratio)
RE – Recovery
efficiency of
applied nutrient
long-term cropping systems
0.3 to 0.5 - N recovery in cereals-typical
0.5 to 0.8 - N recovery in cereals- best management
F-amt. nutrient applied, Y- yield of harvested portion with applied nutrient, Y0- yield of harvested portion with no
applied nutrient, UH –nutrient content of harvested portion of crop, U –total nutrient uptake in aboveground
biomass with nutrient applied, U0 –total nutrient uptake in aboveground biomass with no nutrient applied
Increased Farmer Interest in
Better N Management
• Increased N costs
• Better crop prices
• Calibration and
verification of
newer technologies
• Improved farmer
skills, and availability
of professional
guidance
by crop advisers
“The Market” Nov.1, 2007
Corn grain produced in the U.S. per unit
of fertilizer N used, 1964 to 2005.
1.4
1.15
bu per lb of N
1.3
1.2
*
1.1
1.0
0.9
0.76
0.8
0.7
0.6
*Application rate for 2004 estimated as avg of 2003 & 2005.
0.5
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Since 1975:
51% increase in N efficiency
12% increase in N fertilizer use
Data sources: USDA Ag Chem Use Survey & Annual Crop Production.
Effects of Crop Harvest N Removal on
Net Anthropic Nitrogen Input (NANI)
Figure 1. Net anthropogenic N input (NANI) in major sub-basins of
the Mississippi River Basin estimated from state level statistics.
Source: McIsaac, 2006.
Fertilizer N in California and GHG Emission
802,682 x 0.01= 8,027 metric tons N2O–N emitted
(assuming IPCC 1% factor)
N x 1.57 = 12,602 metric tons of N2O
N2O x 296 = 3.73 million metric tons GWP CO2 equivalent
All GHGs in CA in 2004 (CA EPA, ARB 2007) :
479.74 million metric tons CO2 equivalent
Portion of total that is “fertilizer N induced”
= (3.73/479.74) x 100 = 0.78% of all GWP in California
Source: AAPFCO
• Fertilizer N BMPs can help minimize
potential for residual NO3-N
accumulation & losses
• N source, rate, placement , and
timing …. which may include
–
–
–
–
Urease inhibitors
Nitrification inhibitors
Slow-release materials
Controlled-release materials
• In combination with appropriate, sitespecific cropping system and
conservation practices
– (e.g. conservation tillage, cover crops,
vegetative buffers, managed drainage,
wetlands, bioreactors, etc.)
http://www.floridaagwaterpolicy.com/BestManagementPractices.html
http://www.ipni.net/bettercrops
http://www.fertilizer.org
CONCLUSIONS
• Appropriate fertilizer N helps increase crop
biomass to restore & maintain soil organic
matter (SOM)
• Tillage practices with the least soil
disturbance help maintain SOM
• Intensive crop management can help
minimize GHG emissions, and lower GHG
emission/unit of crop or food produced
• Fertilizer N contributions to agricultural GHG
emissions can range widely, BUT agricultural
emissions are relatively small compared to
other source emissions
• We must continue to strive to improve NUE
QUESTIONS ?
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www.ipni.net