The study area 1.10 Thesis outline 2 Comparison of methods to identify crop productivity constraints in developing countries. A review 2.1 Introduction 2.2 Heuristic model and prototype methods 2.3 Different use of methodologies: a review 2.4 Comparing different methods for the identification of productivity constraints in Tigray 2.5 Discussion 2.6 Conclusion 3 Identifying crop productivity constraints and opportunities using Focus Group Discussions: A case study with farmers from Tigray 3.1 Introduction 3.2. Material and methods 3.3 Results 3.4. Discussion 3.5. Conclusion 4 The importance of local factors and management in determining wheat yield variability in on-farm experimentation in Tigray, northern Ethiopia 4.1 Introduction 4.2 Materials and methods 4.3 Results and Discussion 4.4 Conclusion viii 5 Four years of farmer experimentation on soil fertility in Tigray, northern Ethiopia: Trends in research strategies 5.1 Introduction 5.2 Method 5.3 Results 5.4 Discussion 5.5 Conclusion 6 Grain productivity, fertilizer response and nutrient balance of farming systems in Tigray, Ethiopia: A multi-perspective view in relation to soil fertility degradation 6.1 Introduction 6.2 Materials and method 6.3 Results 6.4 Discussion 6.5 Conclusion 7 Considering change: Evaluating four years of participatory experimentation with farmers in Tigray (Ethiopia) highlighting both functional and human-social aspects 7.1 Introduction 7.2 Methods 7.3 Results and Discussion 7.4 Conclusion 8 Synthesis 8.1 The research project: an overview 8.2 Assessing effectiveness: putting pieces together 8.3 Reflection on process and points of departure 8.4 Impact, livelihood development and scaling 8.