The project combined data from on-farm trials with system modelling to generate the production potential on crop lands for three representative districts in southern Bangladesh. Field crop-soil-climate datasets collected from three years of on-farm trials (two previously funded by FAO and one from the 2005-06 season funded as part of this project) were used to set up and test the APSIM systems model (www.apsim.info) for this production system. Minimum datasets were also collated to quantitatively describe the long-term climate, soils, irrigation resources and management systems for current and proposed cropping systems in the region. Utilising these data, the feasibility of rabi-season cropping systems was simulated using APSIM, incorporating 20 years of climate data (1985-2006) for the three regions: a traditional wheat production area (Jessore) and two new areas (Barisal, Noakhali) are being considered for cropping.
The three years of on-farm trials clearly demonstrated that irrigated wheat can be grown in these regions. Yields (3-4 t/ha) approximated those attained from more traditional wheat production areas. A key question was access to irrigation water. The scoping study suggested that much of the area has a significant amount of soil water stored as surface water or shallow water tables of high quality at the start of the rabi season.
This study provided justification for continued R&D investment in the production of rabi-season crops on currently fallow lands in southern Bangladesh. Specifically, the water resources of southern Bangladesh need to be characterised to determine their potential availability for irrigation in terms of surface and soil water, their distribution, and a record of the types of water bodies and their quality. The impact of temporal and spatial salinity levels on wheat production and tolerance of current and improved varieties to salinity all require deeper consideration. Agronomic practices, especially in the timing and amounts of fertiliser and irrigation, need to be adapted to increase ecological sustainability, profitability and yield.
Finally, to achieve wider extension of agronomy recommendations tailored to each new cropping region, resources are needed to train regional extension officers and their farmer clients.