Frédéric BaudronCIMMYT Ethiopia

f.baudron@cgiar.org

Agroforestry &Food Security:

Assessing the Direct Effectsof Trees on Annual Food Crops

Challenges faced by Annual Food Crop Production

Water scarcity Nutrient scarcity

– N, P Climate change Pests and diseases Energy scarcity

– Labour, ADP, fuel Slow yield gains

– Yield gap– Land scarcity– Undernourished people

(Water scarcity in 2050, from Wallace, 2000)(from Cairns et al., 2012)

(from FAO, 2009)

A Question of Efficiency?

Only 10-30% of water is used by the crop (Wallace, 2000)

Only 20-50% of N ferilizers applied is used by cereal crops (Cassman, 2002)

Less than 0.1% of pesticides applied reach their pest target (Pimentel, 1995)

Management response: Precision agriculture

Genetic response

Management response: Exploiting positive interactions between species

(from Cox et al., 2006)

An Example of Genetic Response: Developing Perennial Grain Crops

Precision Agriculture: when, where, how much?

1.When does it occur?

2.What are the mechanisms?

3.How to maximize it?

Tree - Annual Food Crop facilitation

Increasing Water Availability

The problem: high water loss through runoff, evaporation and deep drainage; shallow root distribution of annuals

Reduced evaporation (from Ong et al., 2000)

Increased soil water (from Joffre and Rambal, 1993)

Hydraulic lift (from Emerman and Dawson, 1996)

N Fixation and Recycling

The problem: production of N fertilizers dependant on fossile energy; highly mobile nutrient,

P Mobilization & Acquisition

The problem: poorly mobile nutrient, mainly in non-available forms in the soil

(from Cox et al., 2006)

Exudation of organic acids by proteoid roots of e.g. Grevillea robusta (Watt & Evans, 1999)

Ectomycorrhizae of e.g. Caesalpinioideae (Högberg, 1992)

Heat and water stress

(from Ong et al., 2000)

Pest control

Rodents: 0.1-0.5 t/ha of field damage in Tigray (Yonas et al., 2010)

(from Koh, 2008)

Interactions

Effect of water availability on heat stress of maize (from Lobel et al., 2011)Effect of nutrient application

on water productivity (from Penning de Vries and Ditèye, 1991)

Minimizing Competition

Tree species selection– Phenology– Pattern of root activity– Plasticity of the root

system Management

– Spacing– Supply of limiting factors– Shoot pruning– Tillage

(from Burges et al., 1998)

(from Schroth et al., 1995)

(Gc × Gt) × E × M

Gc: Diversity of maize varieties– Productivity (e.g. land, water)– Resistance or sensitivity to e.g.

heat, drought, low N, pests & diseases

Gt: Diversity of tree species– Morphology (above and below

ground)– Phenology (inverse or not)

E: Diversity of environments– Climates (semi-arid vs. sub-humid)– Soils (N limited vs. P limited)

M: Diversity of management options– Geometry– Fertilization– No-till vs. Ploughing

0 100 1000 30000%

20%

40%

60%

80%

100%

Transpiration Runoff

Soil evaporation Drainage

Surface mulch (kg DM ha-1)

Wate

r use b

y s

org

hum

(from Baudron et al., in prep)

What to measure (near and away from trees)?

Environmental parameters– Radiation and temperature– Soil water content– N and P balance

Productivity– Crop yield– Biomass production (crop & trees)

Crop stress indicators– NDVI– Canopy temperature

Crop damage inside and outside bird-exclosures

Fate of biocides - phytoremediation

Conclusion: Answering Practical Questions for

Maize Farmers

What happens near trees? What to plant near trees? What management is

needed near trees?

Thank you!