M. S. Rahman
Scientific Officer
Irrigation & Water Management Division, Bangladesh Agricultural Research Institute (BARI), Gazipur
M. Salehin
Professor
Institute of Water and Flood Management, Bangladesh University of Engineering and Technology (BUET), Dhaka
P. K. Sarkar
Principal Scientific Officer
Irrigation & Water Management Division, Bangladesh Agricultural Research Institute (BARI), Gazipur
M. A. R. Akanda
Principal Scientific Officer
Irrigation & Water Management Division, Bangladesh Agricultural Research Institute (BARI), Gazipur
A. U. Haque
Scientific Officer
Tuber Crop Research Center, BARI, Gazipur
AquaCrop model is already parameterized for different crops including potato. In this study, AquaCrop was locally calibrated and tested for potato crop (variety: Diamant). Model parameters that were calibrated using the field experiment data included conservative parameters which are given specific but can or may be cultivar specific, parameters which are dependent on environment and /or management, and parameters which are cultivar specific. The conservative parameters were held constant, and the calibrated model was evaluated by test simulations. The simulation results showed a reasonably accurate prediction of the final aboveground biomass within 9% of the measured value. The predicted tuber yield values were within 15% of measurements, except in the treatment of water stress at stolonization stage, with errors up to 19.031%. The simulated pattern of canopy progression and biomass accumulation over time were close to measured values, with Willmott’s index of agreement for all the cases being ≥0.985 for canopy cover, and ≥0.989 for biomass. Accelerated senescence of canopy due to water stress was difficult to simulate accurately. The model closely predicted the trend in soil water content, but overestimated soil moisture for the three water stress treatment cases.
AquaCrop model, irrigation, potato, model calibration
Central farm, IWM Division, BARI, Joydebpur, Gazipur
Crop-Soil-Water Management
The objective of the study was to calibrate and test AquaCrop model for potato
AquaCrop was calibrated and tested for potato crop (BARI variety: Diamant) using data for one year study (2010-2011) that was conducted at Irrigation and Water Management Division research field, Bangladesh Agricultural Research Institute (24°0´ N, 90°25´ E, and 100 m above mean sea level). The experimental design was a randomized complete block design (RCBD) design with four levels of irrigation. Each treatment was replicated thrice with one additional spare plot. AquaCrop requires the input data files for climate, crop, soil, irrigation, and initial soil water conditions (Raes et al., 2009), which were assembled using the field data. The following treatments were arranged in the experiment:
T1 = Full irrigations (15, 35, 55, 70 DAS, Control); T2 = Water stress at stolonization stage (irrigations at 35, 55, 70 DAS)
T3 = Water stress at tuberization stage (irrigations at 15, 55, 70 DAS)
T4 = Water stress at bulking stage (irrigations at 15, 30, 50 DAS). The experimental site is characterized by a tropical monsoon climate with a cool and dry winter from the October through early March, with temperature ranging from 5° C to 22° C (41° F to 72° F ), with total winter rainfall averages of about 13 cm. Daily weather data were taken from the nearby weather station. The reference evapotranspiration (ETo) for each day of the experiments was computed by the procedure recommended for AquaCrop, using the FAO Penman-Monteith equation as described in Allen et al. (1998). The soil was a silty clay loam having a bulk density of 1.50 gm/cc and volumetric water content at permanent wilting point (PWP) and field capacity (FC) equal to 23% and 43.5%, respectively. Saturated hydraulic conductivity was not measured in the field, and a default value suggested by the model was adopted.
BARI Annual Report 2010-2011
The study was based on experiments conducted for two growing season. It may be concluded that the calibrated AquaCrop model seems to have performed well under water stress condition to predict potato yield in Bangladesh. The simulation results showed a reasonably accurate prediction of the final aboveground biomass within 9% of the measured value. The predicted tuber yield values were within 15% of measurements, except in the treatment of water stress at stolonization stage, with errors up to 19.03%. The simulated pattern of canopy progression and biomass accumulation over time were close to measured values. The model closely predicted the trend in soil water content, but overestimated soil moisture for the three water stress treatment cases. One important future application of AquaCrop would be to compare the attainable against actual yields in a field, farm, or a region, to identify the constraints limiting crop production and water productivity. It would then be very useful for scenario simulations and for planning purposes for use by economists, water administrators and managers.
Report/Proceedings