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)