Modelling water dynamics in coffee systems: Parameterization of a mechanistic model over two production cycles in Costa Rica. Pablo Siles, Patrice Cannavo, Julie Sansoulet, Jean- Michel Harmand and Philippe Vaast CATIE (Centro Agronómico Tropical de Investigación y Enseñensa), Turrialba, Costa Rica CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), Montpellier, France
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Modelling water dynamics in coffee systems: Parameterization of a mechanistic model over two production cycles in Costa Rica. Pablo Siles, Patrice Cannavo,
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Modelling water dynamics in coffee systems:Parameterization of a mechanistic model over two production cycles in Costa Rica.
Pablo Siles, Patrice Cannavo, Julie Sansoulet, Jean-Michel Harmand and Philippe Vaast
CATIE (Centro Agronómico Tropical de Investigación y Enseñensa), Turrialba, Costa Rica
CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), Montpellier, France
Introduction
Water is key issue in the coffee regions of Central America:
– at plot level, complementarity /competition between coffee and various shade tree species
– at landscape level, coffee located in mountainous areas (erosion) and rainy zones providing water for communities downstream.
– Study with Inga (up to 6 species), predominant genus used in CA (70% shaded coffee)
Material and Methods
• Trial established at CICAFE, Central valley of Costa Rica, Date : 1997
• Optimal ecological conditions• High altitude (~1200 m), temperate (~22°C)• high rainfall (>3000 mm), 3 dry Months• slope < 5%
• Agroforestry System (AFS)• Inga densiflora density : 277 trees ha-1
• Shade 40-55%
• Intensive fertilization regime:
Monitoring of water fluxes during 2 years
GR = I + E + T + Rn + ΔS + D
InterceptionI. densiflora
Coffee
Runoff
Transpiration
Soil evaporation
Gross Rainfall
Soil water stock
Drainage
Interception
I = GR - (Stemflow +Throughfall)
Transpiration : Sap flow (coffee & tree) Runoff
Soil water content Stemflow: Inga and coffee
Influence of shade trees on throughfall
Reduction in throughfall in AFS by 14.4% in 2004 and 7.6% in 2005
Gross rainfall (mmd-1)
0 10 20 30 40 50
Th
rou
ghfa
ll (m
m d-1)
0
10
20
30
40
50
60
AFSMC
Gross rainfall (mmd-1)
0 10 20 30 40 50 60
2004 2005
MC AFS MC AFS
LAI Coffee 4.71 4.64 4.60 3.80
LAI I. densiflora - 1.32 - 1.22
Influence of shade trees on stemflow
• Higher stemflow in AFS (41%) could be explained by differences in architecture of coffee plants (40 cm taller, longer branches) in spite of lower coffee LAI
• Low contribution of tree stemflow to the system (1% of rainfall)
Comparison of simulated (solid line) and observed (circles) soil volumetric water contents in the 0-30 and 60-90 cm soil layers in AFS with allocation of water uptake in the various soil layers according to root density
0-30 cm soil layer in AFS 60-90 cm soil layer in AFS
-5
15
35
55
75
95
115W
ater
flux
(m
m d
-1)
200 cm
Water drainage (in mm d-1) at 200 cm soil depth in AFS
• Shade trees modify the coffee architecture resulting in increased coffee stemflow and a lower throughfall
• Runoff was decreased in AFS due to coffee architecture and litter cover, hence less soil erosion and better water quality
• Lower runoff offsets higher interception in AFS, hence a higher infiltration in AFS
• Higher transpiration in AFS slightly lowers drainage in AFS
• The soil water content simulated adequately by the Hydrus model (one the first time this model is used in agroforestry)
• Sound basis to estimate the amount of water drainage and hence nutrient leaching (nitrate)
• No OVERGENERALIZATION, present AFS with only one tree species (Inga), Andosol (fast infiltration) and high rainfall regime (>2500 mm).
• The challenges are to use this approach 1) in more complex systems and 2) in conditions of lower precipitation and different soils (currently underway in India) and 3) upscaling.