integrating trees on farms: what options are available

Integrating Trees on Farms: What Options are Available?

B.I. Nyoka

World Agroforestry Centre (ICRAF)

Transforming lives and Landscapes

Why Integrate trees on Farms

• Trees in agricultural landscapes are an important resource for many smallholder farmers: Trees improve soil fertility and farm resilience to Climate

changeTrees provide food (fruit, nuts, vegetable), fodder, bioenergy,

and fibre. Trees also provide many ecosystem services such as watershed

protection and shade for livestock, honey production. Trees improve productivity of pastures and rangelandsTrees improve Biodiversity conservation because they

ease pressure on protected forest areas.

• Trees can also bring damage to local livelihoods, through harboring pests (e.g. birds on sorghum and millets)

Trends in maize production, food inadequacy and prevalence of undernourishment, Malawi, 1999–2011


Trends in maize yields in Malawi (source: FAOSTAT,


Malawi & Southern Africa: - Challenges

• The region is predominantly dry with high rainfall variability, characterized by frequent droughts and floods (2014/15 is a case in point)

• Most smallholder farmers dependent on rain-fed agriculture.

• 90% of the people depend on wood energy for heating and cooking.

• Women spent about 1.5 hours a day when they do go to collect firewood

Malawi& Southern Africa - Challenges

• Average annual temperature is expected to increase by between 1.5-2.5˚C in the southern part of southern Africa

• By between 2.5 and 3˚C in the northern part of the region

• Increase in frequency of extreme climate and weather events

• Increased frequency of floods and drought, (2014/15 season amply demonstrated this: late start, floods, mid-season drought).

• The region is recognised as one of the most vulnerable regions to climate change because of low levels of adaptive capacity particularly among rural communities

Impact of Climate Change on Crop production

Crop Predicted Yield Reduction( %)

Maize −22

Sorghum −17

Millet -17

Groundnuts -18

Cassava -8

Source: Schlenker and Lobell (2010)


Predicted impact of CC on maize yields in selected countries

Source: Schlenker and Lobell (2010)

Background: southern Africa

Country *Nutrient depletion (kg ha/yr)

**Mean fertilizeruse (kg/ha/yr)N P K

Malawi –48 –7 –37 39.9

Mozambique –23 –4 –19 6

Zambia –13 –1 –12 18.1

Zimbabwe –20 –1 –21 29.1

Tanzania –38 –6 –25 4.4

SSA (Target of 50kg/ha/yr by 2010) 8-12 Source: Henao and Baanante (1999) cited by Mafongoya et al., 2006*; World Bank, 2014** : http://wdi.worldbank.org/table/3.2

Annual nutrient depletion and Fertiliser application in agricultural soils in selected countries in Southern Africa


Challenges of getting organic sources

Animal manure• Due to low livestock ownership and numbers as well as poor diets, availability of cattle manure is very

limited in both quality and quantity • A farmer requires 10-15 cattle to produce adequate manure for a hectare plot.• Average livestock ownership: Chickens=3/HH, Goats=1/HH, Cattle= 0.4 /HHGrain legumes• Low quantity and quality of biomass of some grain legumes bred for high grain yield (e.g. soybean)• Most of the N fixed by grain legumes is harvested with the grain.Green Manure• Due to shortage of land, dedicating a whole piece of land to green manure production (Mucuna and

Lablab) for a whole year is not an option in many parts of MalawiComposts• Only 32% of the farmers surveyed in Balaka produce and use compost manure• Quantities produced were only enough to cover 17% of the farmers’ fields (≈0.9ha).Crop residues • Other than groundnut residues most crop reduces available in most smallholder fields cannot be used to

improve soil nutrient status, without affecting crop yields because they will immobilise nutrients (N).• Options include the addition of large quantities of inorganic N-fertilisers, legume green manures or

residues rich in nitrogen, or other high nitrogen organic sources to overcome the nutrient immobilisationpotential of poor quality residues

Fertlliser Trees• They produce large quantities of protein-rich leaf biomass that decomposes rapidly• Major drawback is that they do not produce food


Fertiliser tree: management options

• Maize-tree intercrops1. Maize-Fertiliser trees (Coppicing types)

(e.g. Gliricidia sepium, Leucaena pp., Senna spectabilisand Acacia angustissima)

2. Maize-Fertiliser trees (Full canopy species)

(e.g. Faidherbia albida)

• Annual Relay Fallows

• Improved fallow (Fertiliser tree-Maize crop rotation)

(e.g. Sesbania, Tephrosia)


Relay fallow of tephrosia as the maize

nears to harvesting

Relay fallow of tephrosia after maize is

harvesting

Two-year Tephrosia fallow produces large quantities of biomass


Maize yield under 4 management systems (1 conventional and 3 agroforestry based systems)

0

1

2

3

4

5

6

7

No Fert No Fert 50% Fert 100 % Fert

No Tephrosia Tephrosia Tephrosia Tephrosia

Mai

ze y

ield

(to

nn

es/

ha)

Tephrosia + fertilizer supplementation

Source: Akinnifesi et al., 2006


Gliricidia-Maize intercrop


Maize yield under 6 different management systems: conventional and agroforestry

0

1

2

3

4

5

6

7

No Fert 50% Fert 100 % Fert

Mai

ze Y

ield

(to

nn

esh

a)

Mineral Fertiliser supplementation

Maize only Gliricidia-maize Intercrop

(3 conventional: no fertilisation, 50% and 100% fertilisation and 3 agroforestry based systems: fertiliser trees, 50% fertilisation + fertiliser trees, 100% fertilisation + fertiliser trees)

Source: Akinnifesi et al., 2006Transforming lives and Landscapes


Faidherbia-Maize intercrop: Full Canopy

Mean yields of maize under and outside canopies of Faidherbia albida over four seasons in Zambia (37 trials per season over 4 regions). Source: Shitumbanuma 2012


Resilience of fertiliser-tree intercrops in the face of Climate Change

0

200

400

600

800

1000

1200

1400

1600

1800

0

1

2

3

4

5

6

7

8

Sole Maize Gs-Maize Sole Maize Gs-Maize Sole Maize Gs-Maize Sole Maize Gs-Maize Sole Maize Gs-Maize

Rai

nfa

ll (m

m)

Mai

ze y

ield

t/h

a

Management system

0% fertiliser 25% fertiliser 50% fertiliser Rainfall

Resilience of fertiliser-tree intercrops in the face of Climate Change

Fodder and other treesExotic Fodder trees Indigenous Fodder

Acacia angustissima Albizia lebbeck

Gliricidia sepium Piliostigma thonningii

Calliandra calothyrsus Faidherbia albida

Sesbania sesban Acacia erioloba

Leucaena spp. Acacia nilotica

Acacia tortilis

Acacia spp.

Dichrostachys senerea

Combretum spp.

Colophospermum mopane

Can be integrated in crop fields, grazing areas, field boundary or along contour bands

Influence of trees on pastures

• Trees influence the composition of grasses as well as how they grow, with a larger proportion of more palatable grass species beneath trees and is consistent and independent of animal resting under the trees.

• By managing tree densities and configurations we can achieve a balanced and productive rangelands and pastures.

• Incorporating native trees in grazing production systems provides both environmental and economic benefits for landholders.

• Shade and shelter provided by trees has considerable value in grazing lands due to reduced animal stress from extreme temperatures

Reducing the burden of collecting firewood Women spend 1.5 hrs per day when they

do go out to collect firewood Such precious time could be saved for

other productive chores if firewood could be sourced on-farms


Carbon sequestration: impact of selected tree-maize intercrops in removal of emissions (baseline emission is 36 t

CO2e ha-1)

Site Tree-maize intercrop Total

(t CO2e

ha-1)

Annual

(t CO2e ha-

1yr-1)

Karonga Gliricidia-maize intercrop 40.5 2.0

Mzimba Gliricidia-maize intercrop 33.2 1.7

Salima Gliricidia-maize intercrop 39.3 2.0

Machinga Gliricidia-maize intercrop 33.7 1.7

Zomba Gliricidia-maize intercrop 34.7 1.7

Mulanje Gliricidia-maize intercrop 31.1 1.6

Mzimba Tephrosia-maize intercrop relay 69.9 3.5

Kasungu Tephrosia-maize intercrop relay 69.4 3.5

Mchinji Tephrosia-maize intercrop relay 72.2 3.6

Lilongwe Tephrosia-maize intercrop relay 70.6 3.5

But why is tree integration still low?

Labour constraints? Animal and fire damage to trees Unsupportive Policies Silver bullet solutions Short planning horizons Lack of support/Low investments compare to other technologies Old colonial style approach of removing trees on agricultural and pasture lands Negative perceptions - often viewed as backward by some bureaucrats.

integrating trees on farms: what options are available

Environment