Eco efficiency of Integrated Soil Fertility Management in Western Kenya Sommer et al 2014 presented at 20th World Congress of Soil Science

1. Rolf Sommer, John Mukalama, Job Kihara, Saidou Koala, Leigh Winowiecki
and Deborah Bossio
www.ciat.cgiar.org
Eco-efficiency of integrated
soil fertility management in
Western Kenya

2. What is eco-efficient agriculture?
“Eco-efficient agriculture increases
productivity while reducing negative
environmental impacts. Eco-efficient
agriculture meets economic, social,
and environmental needs of the
rural poor by being profitable,
competitive, sustainable, and
resilient. …, and generate benefits
for the poor…taking into account the
particular needs of women.”
(CIAT Medium-Term Plan, 2009)

3. Why is it important?
• The need to feed a growing population and
to improve the livelihoods of smallholder
farmers
• Gender equity / mainstreaming
• Conservation of the natural resource basis
• Adaptation to /mitigation of climate change
 "More with less!"

4. The need to feed a growing population
• By 2050 the world’s population will
reach 9.1 billion, 34 % higher than today.
• About 70 % of the world’s
population will be urban
• In order to feed this larger, more
urban and richer population, food
production must increase by 70 %.
• Annual cereal production will need
to rise from 2.1 billion today
to about 3 billion tons
• Annual meat production will need to rise by over 200 million
tons to reach 470 million tons.
(FAO, 2009)

5. Conservation of the environment
• Maximizing the efficiency of inputs while minimizing
their detrimental impact

6. Nitrogen fertilizer use
in sub-Saharan Africa
259
7.8
50
100
150
200
250
300
0
1960 1980 2000
Nfertilizerconsumption(kg/ha)
China (1.26 M km²)*
Sub-Saharan Africa
(2.21 M km²)*
*Arable land and Permanent
crops (FAO data for 2010)
Source: IFASTAT 2014

7. Source: EcoFys 2013
World GHG emissions flow chart – data for year 2010
Nitrous oxide emissions
– contribution to global warming
Approximately 75 % of N2O
emissions are from soils
= 5 % of the global total GHG
emissions
Africa's share of the soil-related
N2O emissions is ~30 %
= 1.5 % of the total GHG
emissions

8. 22%
13%
7.0%
4.7%
4.2%
3.6%
2.4%
1.8%
1.7%
1.5%
1.4%
1.4%
1.3%
1.2%
1.2%
1.1%
1.1%
1.0%
0.98%
0.97%
0.96%
0.86%
0% 5% 10% 15% 20% 25%
China
USA
India
Russian Federation
Indonesia
Brazil
Japan
Canada
Germany
Iran, Islamic Rep.
Mexico
Australia
United Kingdom
Korea, Rep.
South Africa
France
Saudi Arabia
Pakistan
Thailand
Argentina
Italy
Malaysia
Why bother? – because every bit counts
Country contribution to total GHG emissions

9. Adaptation & mitigation of climate change
• Climate smart agriculture
– increased production
– increased system resilience
– reduced greenhouse gas
emissions
• year-2030 aspirational
mitigation targets to meet the
+2 °C goal:
"The agricultural sector needs to achieve emission reductions
of about 600 Mt CO2eq./yr from 2010 to 2030 to achieve this
target and avoid dangerous climate change."
(CCAFS, 2014)

10. Eco-efficient agriculture in Africa
• Integrated Soil Fertility
Management (ISFM)
– stepwise adoption
– maximize fertilizer and
organic resource use
efficiency and crop
productivity
– include appropriate fertilizer
and organic input
management in combination
with improved germplasm
Resourceuseefficiency
Responsive
soil
Poor, less
responsive soil
Germplasm
& Fertilizer
Germplasm
& Fertilizer
+ Organic
resource
mgmt.
Germplasm
& Fertilizer
+ Organic
resource mgmt.
+ Local
adaptation
Movement towards resource integration
ISFM
Current
practice
• The long-term sustainability / eco-efficiency of ISFM has
not been studied in great depth

11. CIAT ISFM long-term trial in West Kenya
("INM3")
• Since 2004
• Near the village of Madeya, 50 km northwest of Kisumu
• Humid tropical climate, at 1331 m above sea level
• Acric Ferralsol (>70 % clay, low CEC, pH 4.9-5.5, topsoil SOM 3.4 %)
• Each year has a long- and a short-rainy season
• Test the impact of:
– Application of farm yard manure (FYM)
– Maize stover residue retention
– Maize mono-cropping vs. intercropping (with soybean) and maize-
rotation with Tephrosia candida
– various levels of N and P fertilizer application
• split-split-split plot design

14. Maize yields
• Average and standard deviation of all plots
0
2
4
6
8
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Maizeyield(Mg/ha)
Year

15. Maize yields by treatments
• significant effect of FYM application
min. rep max-min max. rep
LSD
0
1
2
3
4
5
6
Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T
R- R+ R- R+
Minus FYM Plus FYM
Maizeyield(Mg/ha)
N0_P0
N0_P60
N30_P60
N60_P60
N90_P60

16. Maize yields by treatments
• significant effect of P-fertilizer application – less though
when FYM is applied
min. rep max-min max. rep
LSD
0
1
2
3
4
5
6
Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T
R- R+ R- R+
Minus FYM Plus FYM
Maizeyield(Mg/ha)
N0_P0
N0_P60
N30_P60
N60_P60
N90_P60

17. Maize yields by treatments
• N-fertilizer application above 30 kg/ha has no significant
effect
min. rep max-min max. rep
LSD
0
1
2
3
4
5
6
Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T
R- R+ R- R+
Minus FYM Plus FYM
Maizeyield(Mg/ha)
N0_P0
N0_P60
N30_P60
N60_P60
N90_P60

18. Maize yields by treatments
• highest maize grain yields per season under M-T rotation;
but not high enough to match maize double-cropping annual yields
min. rep max-min max. rep
LSD
0
1
2
3
4
5
6
Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T Intercr M-M M-T
R- R+ R- R+
Minus FYM Plus FYM
Maizeyield(Mg/ha)
N0_P0
N0_P60
N30_P60
N60_P60
N90_P60

19. In-depth studies on eco-efficiency
Goals:
• assess the eco-efficiency of current
farmers practices and ISFM as a
potential climate smart, eco-efficient
farm intensification option;
– quantify the GHG footprint / climate
change mitigation potential of these
systems;
– Crop modeling (CropSyst) of N-dynamics
• describe tradeoffs between eco-
efficiency, climate change mitigation
potential and food security needs

20. In-depths studies on eco-efficiency
Rotation FYM
application
Maize
stover
retention
N-fertili-
zation
(kg/ha)
P-fertili-
zation
(kg/ha)
Description
M-M + - 0 60 resource-poor livestock
farmer
T-M + + 30 60 best-bet ISFM
T-M - - 0 0 no fertilizer
M-M - + 90 60 intensive maize farmer
Selected treatments

21. Simulation results: yield and biomass
0
2
4
6
8
10
12
14
N0 N0 N90 N30
T-M M-M M-M T-M
R- R- R+ R+
Minus FYM Plus FYM Minus FYM Plus FYM
Mg/ha
Observed Yield
Simulated Yield
Observed AGB
Simulated AGB

22. 0
0.1
0.2
0.3
0.4
0.5
0.6
0
50
100
150
200
250
300
01/Sep/13 01/Oct/13 31/Oct/13 30/Nov/13 30/Dec/13
Soilmoisture(m/m)
N2Oflxu(gN/ha/d)
N2O flux, simulated observed Soil moisture, 0-14 cm
0
0.1
0.2
0.3
0.4
0.5
0.6
0
50
100
150
200
250
300
01/Sep/13 01/Oct/13 31/Oct/13 30/Nov/13 30/Dec/13
Soilmoisture(m/m)
N2Oflxu(gN/ha/d)
N2O flux, simulated observed Soil moisture, 0-14 cm
0
0.1
0.2
0.3
0.4
0.5
0.6
0
50
100
150
200
250
300
01/Sep/13 01/Oct/13 31/Oct/13 30/Nov/13 30/Dec/13
Soilmoisture(m/m)
N2Oflxu(gN/ha/d)
N2O flux, simulated observed Soil moisture, 0-14 cm
0
0.1
0.2
0.3
0.4
0.5
0.6
0
50
100
150
200
250
300
01/Sep/13 01/Oct/13 31/Oct/13 30/Nov/13 30/Dec/13
Soilmoisture(m/m)
N2Oflxu(gN/ha/d)
N2O flux, simulated observed Soil moisture, 0-14 cm
Plus FYM, R-, M-M, N0
Plus FYM, R+, T-M, N30
Minus FYM, R-, T-M, N0
Minus FYM, R+, M-M, N90
Simulation results: N2O fluxes
0
0.1
0.2
0.3
0.4
0.5
0.6
0
50
100
150
200
250
300
01/Sep/13 01/Oct/13 31/Oct/13 30/Nov/13 30/Dec/13
Soilmoisture(m/m)
N2Oflxu(gN/ha/d)
N2O flux, simulated observed Soil moisture, 0-14 cm

23. Simulation results: N2O fluxes and N-uptake
0
50
100
150
0
1
2
3
4
5
6
7
17 70 106 162
N-uptakeIkg/ha)
N2Oemission(kgN/ha/season)
Total N applied (kg/ha)
• Total N applied to the system does not explain well
N2O emissions!
Minus FYM Plus FYM Minus FYM Plus FYM
R- R- R+ R+
T-M M-M M-M T-M
N0 N0 N90 N30

24. N-balance (short rainy season 2013)
FYM Minus FYM Plus FYM Minus FYM Plus FYM
Maize stover retention R- R- R+ R+
Rotation T-M M-M M-M T-M
N & P level N0, P0 N0, P60 N90, P60 N30, P60
Total N uptake (kg N/ha) 81 94 154 108
N-conc. AGB (%) 1.67 1.00 1.83 0.99
N2O emissions (kg N/ha) 2.2 5.7 3.4 2.9
N-leaching (kg/ha) 3.2 2.9 3.2 2.9
Fertilizer N (kg/ha) 0 0 90 30
Organic N (kg/ha) 17 70 16 132
Total N applied (kg/ha) 17 70 106 162
Loss of applied N as N2O 12.7% 8.2% 3.2% 1.8%
N-balance (kg/ha) -64 -24 -61 49
Apparent N-recovery 4.6 1.3 1.5 0.7
kg crop yield per kg
nutrient applied 116 59 37 30

25. 0
4
8
Long-term dynamics
0
5
10
15
20
LR SR LR SR LR SR LR SR LR SR LR SR LR SR LR SR LR SR LR SR
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Mg/ha
Plus FYM, R-, M-M, N0
YIELD simulated
AGB simulated
130
135
140
145
150
1/1/04 1/1/05 1/1/06 1/1/07 1/1/08 1/1/09 1/1/10 1/1/11 1/1/12 1/1/13 1/1/14
MgC/ha
SOC, 0-1.1 m
N2O losses (kg N/ha)

26. Preliminary conclusions
• Negative N-balance in three out four tested
treatments
• Observed and simulated SOM depletion  FYM
application alone is not a guaranty for sustainability
• "Chaotic" N2O fluxes – does Tephrosia application
reduce emissions? (Further research required!)
• Eco-efficiency assessment also requires
consideration of tradeoffs (e.g. loss of annual maize
yields with inclusion of green manure cover crop)

27. Thank you!