PhD defence: Climate smartness of smallholder crop-livestock systems – University of Copenhagen

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PhD defence: Climate smartness of smallholder crop-livestock systems

PhD defence by Daniel Ortiz Gonzalo

Climate-smart approaches are currently being promoted in tropical, agricultural development. However, the scarcity of data on smallholder systems hampers the understanding of synergies and trade-offs for low emission development. The main objective of this study was to assess, by using different methodological approaches, the extent of the climate smartness of mixed farming systems in the Central Highlands of Kenya. The study was conducted in an agroforestry landscape of smallholder crop-livestock systems undergoing agricultural intensification in Murang’a and Nyeri Counties. Here social (participatory rural appraisal – PRA) and natural science methods (empirical and dynamic modelling, field experiments and laboratory incubations) were applied to achieve four sub-objectives: 1) an estimation of whole-farm GHG balances and targeting of GHG hotspots, 2) experimental measurements of GHG emissions on multiple spatial and temporal scales, 3) an assessment of synergies, trade-offs and long-term effects of climate-smart practices and 4) the identification of processes and factors that build farm resilience in the region. Although intensification processes ─ reduced farm size, increased livestock densities and higher inputs ─ resulted in higher GHG emissions per unit of area, this increase was partially counterbalanced by greater carbon (C) sequestration in soils and woody biomass. GHG calculators stood out as user-friendly tools for identifying GHG hotspots and mitigation options. However, the experimental measurements showed that these tools overestimated nitrous oxide (N2O) emissions from soils and manure management systems. Overcoming the inherent complexity of smallholder systems was the major challenge for GHG sampling strategies, in which multi-scale stratification helped to capture temporal and spatial variabilities. Preliminary results on dynamic modelling showed triple wins from practices such as soil fertility management, improved cattle feeding and enhanced manure management. Practical interfaces and affordable platforms are needed to enable farmers to benefit from these tools. Further benefits from information technology (e.g. weather forecasts), linked to local traditional knowledge, will facilitate a shift towards informed decisions in a changing climate. Advances in overcoming the shortage of data will increase the explanatory power and facilitate nuanced, tailored options for triple wins in tropical regions.

Supervisors

Sander Bruun, Associate Professor, University of Copenhagen, Denmark
Andreas de Neergaard, Professor, University of Copenhagen, Denmark
Philippe Vaast, Senior scientist, Montpellier SupAgro & CIRAD, UMR EcoSols, France
Todd S. Rosenstock, Senior scientist, ICRAF, World Agroforestry Centre, Kenya
Myles Oelofse, Consultant, University of Copenhagen, Denmark
Alain Albrecht, Research Director, Montpellier SupAgro & IRD, UMR EcoSols, France

Assessment Committee

Augustin del Prado, Research Professor, Basque Centre for Climate Change, Spain
Eric Ceschia, Research Director and Associate Professor, CESBIO (CNES/CNRS/UPS/IRD), France
Jørgen E. Olesen, Professor, Aarhus University, Denmark
Lars Stoumann Jensen, (Chairman) Professor, University of Copenhagen, Denmark

The defence is followed by a reception on the 6th floor in meeting room R660/661.