Post on 22-Jun-2020
Nitrogen management for futurefood security: sub-Saharan Africa
case study
Masso et al. 2016ARC-INI
Melbourne (Australia), 05 December 2016
Take home message from SSA
• Too little N for food production• Too much N losses to the environment• Excessive yield gaps due to land degradation
i.e. poor N agronomic use efficiency• Many opportunities available to reverse the
trendoProvided supportive policiesoProvided significant research
• Highest population growth
Food security (White et al. 2012)
• Sufficient food (quantity)• Nutritious food (quality)• Safe (tolerable level of contaminants)• Balanced diets (diversity)
Low N use forproduction (Wanzala 2011)
0 5 10 15 20 25 30 35 40 45 50
South AfricaMalawi
ZimbabweZambiaKenya
Ivory CostGhana
EthiopiaRwanda
TogoCameroon
TanzaniaBurkina Faso
GabonEritreaSudan
AngolaMadagascar
MozambiqueGambiaNigeria
NamibiaSenegalBurundiGuineaUganda
NigerMali
Average nutrient use (kg ha-1)
Sele
cted
sub
-Sah
aran
Afr
ican
cou
ntri
es
Low N use for production (cont’d)
Country kg N ha-1 yr-1 Country kg N ha-1 yr-1
Benin -16 Mali -11
Botswana -2 Nigeria -37
Cameroon -21 Rwanda -60
Ethiopia -47 Senegal -16
Kenya -46 Tanzania -32
Malawi -67 Zimbabwe -27Chianu et al. 2012
Low N use forproduction (cont’d) (ACS 2016)
0 10 20 30 40 50 60 70 80 90 100
East Asia
South East Asia
North America
West and Central Europe
Australia and New-Zealand
west Asia
South Asia
Pacific Islands
North Africa
East Europe and Russia
Central Asia
Central America
Sub-Saharan Africa
Average crop performance as percent of potential yields
Sele
cted
Wor
ld r
egio
ns
Poor quality of N inputs (Bold et al. 2015)
0
2
4
6
8
10
12
0 10 20 30 40 50
Perc
enta
ge o
f the
369
pro
duct
s sol
d as
ure
a
Nitrogen content (%) 46
Poor input and output markets (Guo et al. 2009)
Country Farm-gate urea costsA Farm-gate maize pricesB Value-cost ratio
Market access
USD (metric ton)-1
High Med Low High Med Low High Med Low
Burundi 659 684 693 234 200 185 2.5 2.0 2.0
Kenya 458 486 522 288 238 182 2.8 2.3 1.5
Rwanda 647 675 699 236 209 178 2.0 1.5 1.5
Tanzania 526 552 622 245 214 128 3.3 2.8 1.3
Uganda 553 577 613 244 202 168 3.0 2.1 1.8
Low protein content in food crops
Yie
ld o
r pr
otei
n co
nten
t (
from
low
to h
igh)
Relative N availability (from low to high)
Protein
Yield
Zone of poverty adjustment Zone of luxury updakeZone of minimumpercentage
Wheat (Selles and Zentner 1998)
Undernourishment (ACS 2016)
0
5
10
15
20
25
30
35
40
45
50
Sub-Saharan Africa Eastern Africa Central Africa Southern Africa Western Africa
Und
erno
uris
hed
popu
lati
on (%
)
Sub-Saharan African regions
1990-1992 2014-2016
N deposition ≈ Fertilizer rate
Galy-Lacaux and Delon (2014); Vet et al. (2014)
Eutrophication (Zhou et al. 2014)
Butterbach-Bahl (2014)
N: P ≤ 8 (Lemley et al. 2014)
N agronomic use efficiency (Ghosh et al. 2015)
Crop Yield (t ha-1) Agronomic efficiency
(kg grain kg N-1)
N alone N+PK N alone N+PK
Rice (wet season) 3.28 3.82 13.5 27
Rice (summer) 3.03 6.27 10.5 81
Wheat 1.45 2.25 10.8 20
Pearl millet 1.05 1.65 4.70 15
Maize 1.67 3.23 19.5 39
Sorghum 1.27 1.75 5.30 12
• Dobermann (2005) REN = (UN-U0)/FN (Systems with sufficient N use for production) AEN = (YN-Y0)/FN (Systems with too little N use for production)
Balanced fertilization (Wendt, personal communication)
0
1
2
3
4
5
6
7
Maize in Burundi (44sites)
Maize in Mozambique(17 sites)
Maize in northernRwanda (17 sites)
Maize in easternRwanda (59 sites)
Yie
ld (
met
ric
tons
ha-1
)
Control NPK yield increment Secondary/micronutrient yield increment
N fertilizer fractionation (Perez et al. 1996)
N Fertilizer treatment (kg N ha-1) Head rice yield
(t ha-1)
Protein
content (%)Basal Maximum
tillering
Panicle
initiation
Flowering Total
0 0 0 0 0 1.97 5.62
120 0 60 0 180 4.39 7.58
60 60 60 45 225 5.69 9.56
Organic amendment and erosion control
Vanlauwe, personal communication
Improved varieties (Vanlauwe et al. 2011)
Caution (Hawkesfold 2014)
0
10
20
30
40
50
60
0
1
2
3
4
5
6
7
8
9
10
0 48 96 144 192 240 288
N le
ache
d (k
g ha
-1)
or N
UE
(kg
kg-1
)
Gra
in y
ield
(t h
a-1)
N fertilizer applied to winter wheat (kg N ha-1)
N leached Grain yield NUE
Limiting factor: Resource-constrained smallholder farmers
Innovation (Wendt, personal communication)
Country Crops Yield Increment (t ha-1) Gross margin (USD ha-1)
Burkina Faso Rice 1.7 NS
Ethiopia Maize 1.3 NS
Madagascar Rice 2.0 NS
Mali Rice 1.6 NS
Niger Rice 1.5 NS
Nigeria Rice 2.5 NS
Rwanda Rice 1.1 NS
Maize 1.1 NS
Senegal Rice 1.6 NS
Togo Rice 1.0 NS
Bangladesh Cabbage NSA 960
Tomato NS 1622
Urea briquette
BNF & rhizobia inoculants (Bouaziz, personal communication)
Legume crop Range of N fixed (kg ha-1 yr-1)
Faba bean 54-200
Sesbania 45-552
Alfalfa 290-299
Lentil 165-189
Pea 52-77
Vicia 80-102
Common bean 40-70
Rotation (Waddington et al. 2004)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Groundnut Maize Maize Groundnut Maize Maize
Gra
in y
ield
(t h
a-1)
Rotation sequence
Groundnut grain yield
Maize grain yield in mono-cropping
Additional maize grain yield in rotation
Smallholder farmers’ performance (often): BNF < 5 kg ha-1 (Mapfumo 2011)
Policy considerations
Agronomic policies• Extension services for promotion of GAP• Operationalization of regulatory frameworks for
inputs• Improved fertilizer recommendations (balanced
fertilization)Socio-economic policies
• Input and output markets for profitability• Infrastructure: accessibility to markets• Financing mechanisms for smallholder farmers• Land tenure systems
Research
• Fine-turn crop specific N application rates & ISFM• Identify smart subsidies for N inputs• Assess market policy for profitability• Assess national, regional and continental N budgets
to inform policies• Address N inefficiencies in the food supply chain• Analyse the feasibility of organic waste recycling i.e.
from cities to farming communities• Determine the threshold values of nitrates and
nitrites in food commodities for health benefits vs.risks
Concluding remarks: Towards INMS
Henao &Banante (1999)
LVBC (2012)
Butterbach-Bahl (2014)