A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Agricultural Systems and Engineering, School of Environment, Resources and Development.

Thesis (M.Sc.) - Asian Institute of Technology, 2006

Rice is the staple food of 20 million people of Sri Lanka, which is grown as rainfed as well as under supplementary irrigation in minor and major irrigation schemes. Minor irrigation schemes contribute to a major portion of rice production in dry zone of the country. The farmers in minor irrigation schemes face many hardships, which eventually result in yield variability. This study was conducted in three selected minor irrigation schemes in Anuradhapura district, Sri Lanka with the objective to investigate the causes underlying the existing gap in rice yield between actual farm level and potential farm level, and to identify the constraints and suitable yield promoting and protecting measures and policy level assistance required in order for minimizing the existing gap. The data were gathered using a questionnaire and both primary and secondary information were collected various stakeholders. Inadequate use of inputs, improper management practices, lack of knowledge, unsatisfactory extension services and inadequate support from existing policies, were observed to maintain a yield gap. Three major causes namely variety used, land ownership and seed rate had the highest impact on the grain yield. Use of low yielding varieties (BG300), rice production by land owners against tenant cultivators with respect to input use and excessive seed rates significantly contributed to the yield gap (p=0.01). Therefore, educating the farmers to use high yielding varieties, optimum crop management and to use the recommended seed rate showed promising results. It is the policy level assistance combined with the institutional commitment in providing services, inputs and farmer education that would contribute to bridge the yield gap between farmers' yield and potential farmer yield