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Calibration and Evaluation of Three CROPGRO Models under Different Water Regimes in a Semi-Arid Tropical Environment PowerPoint Presentation
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Calibration and Evaluation of Three CROPGRO Models under Different Water Regimes in a Semi-Arid Tropical Environment. Kindie Tesfaye Haramaya University, Ethiopia 16 Dec 2008. Outline of presentation. Introduction Ethiopia Subject Methodology Results Conclusion. Introduction.

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Calibration and Evaluation of Three CROPGRO Models under Different Water Regimes in a Semi-Arid Tropical Environment

Kindie Tesfaye

Haramaya University, Ethiopia

16 Dec 2008

outline of presentation
Outline of presentation
  • Introduction
    • Ethiopia
    • Subject
  • Methodology
  • Results
  • Conclusion

The topic presented is result of research conducted in Ethiopia

Ethiopia is one of the ancient civilized countries

Has its own calendar (Julian) and Alphabets

Federal administration (14 states)

country profile
Country profile

Location: 8o 00 N, 38o 00 E

Area: 1.13 million sq km (437,794 sq miles)

Elevation: -125 to 4620 m

Population: 75 million (UN, 2007)

Capital:Addis Ababa

Major languages:Amharic, Oromo, Tigrinya, Somali, English (schools)

Major religions:Christianity, Islam

Main exports:Coffee, hides, cereals, oilseeds, grain legumes, beeswax, sugar, cotton, cut flowers, livestock products

Natural recourses: reserves of gold, platinum, copper, potash, natural gas, petroleum, hydropower

Tourist attractions: National game reserves (parks), historical places, the oldest human fossils found (e.g. Lucy-3.18 m yrs old).

endemic animals and plants
Endemic Animals and Plants

23 endemic birds

Chilada Baboon

Walia Ibex

Red fox

Mountain Nyala

Colobus Monkey

Oryx Spps.

Many plant genetic resources

country profile historical places
Country profile-historical places

Blue Nile Water Falls

Negash Mosque- 2000 yrs old

Sofamar Natural cave

Axum Stelle- > 2000 yrs old

Lalibela rock hewn churches-built in the 12th C.

Axum Zion- the oldest church

Fasilede Palace –built in 16th C


Climate variability

Recurrent drought

Crop failures


Soil Degradation

  • Almost half of the country is in the semi-arid climate belt
  • Agricultural decision making is difficult
    • Climate variability
    • Climate change
    • Poor research and extension coverage
    • lack of interdisciplinary approach
  • Grain legumes (drybean, chickpea, cowpea) are relegated to marginal areas
      • the majority of the production of these crops comes from the semi-arid parts of the country

Crop models could play an important role in managing agricultural production in the these areas because:

    • Involve integrated approach (climate, soil, crop, management) at once
    • fast results
    • Inexpensive

The CSM-CROPGRO model has been used to study and evaluate several production problems including:

      • climate change (e.g. Mera et al., 2006; Challinor and Wheeler, 2008)
      • spatial yield variability (Paz et al., 2001)
      • water related constraints (e.g. Ruiz-Noueira et al., 2001)
      • plating date and cultivar selection ( Cooper et al., 2006)
      • plant population and fertilizer interactions (Meirles et al., 2002)
      • optimum irrigation optimization (Faria et al., 1997; Heinemann et al., 2000).

To calibrate and evaluate CROPGRO-drybean, chickpea and cowpea under three water regimes in a semi-arid tropical environment

  • Site: Dire Dawa
      • latitude 9o6’N
      • longitude 41o8’ E
      • altitude 1197 m
  • Season: Three seaosns
      • Dec, 2001-March, 2002
      • April-July, 2002
      • Oct, 2002-March, 2003
  • Treatments: Three water regimes
      • Well-irrigated control (C)
      • Mid-season water deficit (MS)
      • Late-season water deficit (LS)
      • Three crops (drybean, chickpea, cowpea)
  • Design: Split-plot in RCBD (WR: main plot;
      • Water regimes: main-plot; Crops: sub-plot
data collection
Data collection
  • Phenology
  • Growth, Yield & YC
  • Soil water
  • Physiology (PS, SC, LWP)
  • Canopy and soil temp.
  • Radiation interception
  • Weather
  • Soil (initial, profile)
  • Crop management
  • Data organization for DSSAT format
    • data were organized and all the required files created (Soil.Soil, WTH files, Xfiles, A files, T files)
  • Calibration
    • the 2001/2003 well-irrigated treatment of the respective spps.
    • Stepwise calibration followed
      • First phenological parameters using Gencalc
      • Growth and yield: sensitivity analysis using the data in the Tfiles
  • Evaluation
    • Comparing simulated and measured phenology, growth and yield parameters with using
      • RMSE
      • MAD
      • CV (%)
      • Willmot’s Index of agreement (d)
      • Coefficient of determination (R2)
results calibration

Table 1. Calibrated genetic coefficients of drybean, chickpea, cowpea using data from a well-irrigated experiment

results model evaluation2
Results-Model Evaluation…

2. Days to flowering (dap)

results model evaluation3
Results-Model Evaluation…

3. Physiological maturity

results model evaluation5
Results-Model Evaluation…

4. Growth-chickpea

results model evaluation7
Results-Model Evaluation…

4. Grain yield (kg ha-1)

results model evaluation8
Results-Model Evaluation…

5. Relative yield reduction

results model evaluation9
Results-Model Evaluation…

5. Simulated WSF vs. Measured LWP

  • The CSM-CROPGRO- drybean, chickpea and cowpea models accurately simulated:
      • soil water dynamics in the root zone layer and the duration and intensity of water deficit occurrence during the growing seasons
      • the seasonal pattern of LAI, biomass accumulation and pod growth under different water regimes although accuracy is less in the MS treatment, and
      • grain yield variability with water supply.
  • The models overestimated the duration of physiological maturity under water deficit conditions suggesting the need for further improvement in this regard.
  • If properly calibrated, the models have shown their ability to be used as decision support tools in:
      • irrigation water management,
      • choice of cultivars to different water supply environments,
      • prescreening of genotypes for drought tolerance and
      • determining the occurrence and severity of agricultural drought in the semi-arid tropical environments.