Simulation Of Water Use Efficiency To Tackle The Drought

Rainfed environments are characterised by unpredictable and highly variable seasonal rainfall and hence highly variable yields. Water use efficiency (WUE, yield per unit of water use) is commonly used for agricultural production with limited water resources. Expertise working towards the water resources need to address the multitudinous aspects in which cropping systems and amounts, timing and methods of irrigation, and fertilizer applications may be changed to improve WUE while maintaining yield and harvest quality goals. Since experimentation cannot address all scenarios accurate simulation models may fill in the gaps. Crop simulation models are used widely to predict crop growth and development in studies of the impact of climatic change. The present paper explains the model for WUE for an underutilised crop, bambara groundnut under drought as a sub-module of BAMGRO main model (Karunaratne, 2009). This quantitative model explains the root growth, root distribution and water uptake on daily basis under variable climatic conditions. The model links the size and distribution of root system to the capture of water over the growing period. The model was calibrated using glasshouse experimental data, Nottingham, UK and published information. It was validated against 2 years of independent data sets (2007, 2008) from Nottingham and field site at Notwane, Botswana. Although the limited information on root growth is available, validation of soil moisture against glass house and field reported satisfactory results.