Confirmation of Candidature - Candidate : Brintha Nishantha Kumara Karunarathna

The yield gap is defined as the difference between the crop yield potential and the achieved crop yield. Yield gap analysis of individual crops has been performed at local to regional scales. But yield gaps at the cropping system level are less understood and quantified. This PhD research aims to identify the opportunities to reduce yield gaps at the cropping system level in small- and large-scale farming across different regions. Through a systematic literature review, different approaches and metrics used to evaluate the yield gap at the cropping system level  have been identified. Five large-scale farms from Australia and small-scale farms from Sri Lanka will be used as example farms for the study. The actual yield will be collected from published records and farmer's surveys in both countries. The Agricultural Production Systems sIMulator (APSIM) will be used to simulate the yield potential by incorporating climate and soil data. The yield gap at the cropping system will be quantified and compared using different approaches identified in the systematic review such as average yield across the cropping system, individual crop yields within the cropping system, nutritional indicators, financial indicators, and equivalent yield across small- and large-scale farms. Scenario analyses will be conducted to identify management strategies for individual crops and cropping system designs that can narrow yield gaps. The proposed study will identify approaches used to quantify the yield gap at the cropping system level and discuss the similarities and system-specific influencing factors for the yield gap at the cropping system level in both small- and large-scale farming. In addition, the PhD research will explore the best management practices for individual crops at the cropping system level and cropping system design for small- and large-scale farming that can narrow the yield gap at the cropping system level. This knowledge will guide small- and large-scale farmers and policymakers in narrowing the yield gap at the cropping systems level.

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