Reconciling Food, Energy, And Environmental Outcomes: Three Essays On The Economics Of Biomass Management In Western Kenya

This dissertation explores human-environment interactions, focusing on on-farm biological resources (biomass) and crop residues, in particular, and how they can meet the competing demands of food production, energy generation, and environmental conservation in SubSaharan Africa. The empirical setting is rural western Kenya, where maize residues, one of the largest sources of on-farm biomass, constitute a large portion of livestock diets, contribute to household energy needs, and are fundamental in maintaining and improving soil fertility. The three dissertation essays analyze the uses and value of crop residues in tropical smallholder agriculture from several di↵erent perspectives and using di↵erent methodological approaches, all based on data from the western Kenyan highlands. The first essay (Chapter 2) treats non-marketed crop residues as factors of household production, accounting for their long-term benefits when used for soil fertility management. Empirically, the essay estimates a household-level maize production function and calculates the shadow value of maize residues as suggested by the theoretical framework and empirical estimates. This estimated value is substantial-$0.06-08 per kilogram and $208 per average farm-and is higher for poorer households. The second essay (Chapter 3) analyzes crop residue use in an intertemporal setting and develops a dynamic bioeconomic model of agricultural households. The model combines an econometrically estimated production function and a calibrated soil carbon flow equation in a maximum principle framework to determine the optimal application rates of mineral fertilizer and crop residues. The results yield an estimated equilibrium value of soil carbon in the research area-$138 per metric ton-and highlight the significant local private benefits of soil carbon sequestration, and the potential to simultaneously increase food production and sequester carbon. Finally, the third essay (Chapter 4) considers one of the primary challenges in small-scale second-generation biofuel development-the provision of feedstocks. The essay estimates the potential availability and cost of purchasing maize residues from smallholder farmers and transporting them to a hypothetical small-scale pyrolysis-biochar plant in western Kenya. Feedstock provision costs depend on regionally specific agro-ecological and socio-economic conditions, with implications for economic viability in Kenya and, by extension, other rural settings