Exploring the socioeconomic and environmental factors influencing smallholder macadamia production and productivity in Malawi.

Zuza, Emmanuel (2023). Exploring the socioeconomic and environmental factors influencing smallholder macadamia production and productivity in Malawi. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.000166a8


Macadamia (Macadamia integrifolia Maiden & Betche) is a highly valued crop in Malawi. The crop is a vital source of food security and ecosystem services, and its high-export cash value makes it a key contributor to the country's economy. Malawi ranks seventh in global macadamia production, comprising two subsectors: smallholders and commercial estates. However, significant yield gaps have been reported between smallholder and commercial estate producers. While commercial estates achieve higher average annual tree yields (30 kg), smallholder yields remain consistently low, averaging at or below 10 kg tree-1 year-1. Improving macadamia productivity among smallholders can help reduce poverty, improve household food security, and promote economic growth in Malawi. Despite the significant contributions of smallholders in the Malawian macadamia subsector, research on the factors influencing the crop's productivity has primarily focused on commercial estate production. To address this knowledge gap, this Ph.D thesis focuses on smallholder macadamia production in Malawi. The thesis examines the socioeconomic characteristics of smallholder macadamia farmers, including demographics, cultivar preferences, and production constraints. Secondly, it evaluates the climatic factors influencing smallholder macadamia production and predicts the current and future suitable geographical areas for the crop. Lastly, it assesses the soil fertility status of smallholder macadamia farms in relation to macadamia production requirements. Results of this study reveal that the majority (62%) of macadamia smallholders are over 50 years of age and consider farming their main occupation. However, this poses significant risks to the macadamia subsector, as older farmers are risk-averse and less innovative, hindering their willingness to adopt new agricultural technologies and ability to learn. Regarding cultivar preferences, the study finds that smallholder macadamia farmers prefer high-yielding cultivars with superior nut qualities, such as large and heavy nuts, and extended flowering periods. The most preferred macadamia cultivars in descending order are Hawaiian Agricultural Experimental Station (HAES) 660, 800, 816, and 246, which are the "core" of established cultivars in Malawi. The study identifies insect pests, diseases, market availability, strong winds, and a lack of agricultural extension services as the most significant challenges affecting smallholder macadamia farmers. The study's suitability analysis reveals that the ensemble model has an excellent fit and high performance in predicting the current agro-climatically suitable areas for macadamia production (AUC = 0.90). The findings show that precipitation related variables (60.2%) are more important in determining the suitable areas for growing macadamia than temperature related variables (39.8%). The model results show that 57% (53,925 km2) of Malawi is currently suitable for macadamia cultivation, with the central region having the highest suitability (25.8%, 24,327 km2) and the southern region the lowest (10.7%, 10,257 km2). Optimal suitability (26%, 24,565 km2) is observed in the highland areas with elevations ranging from 1000–1400 metres above sea level (m.a.s.l.). Under the intermediate emission scenario (RCP 4.5) and the pessimistic scenario (RCP 8.5), the impact models predict net losses of 18% (17,015 km2) and 21.6% (20,414 km2), respectively, in the extent of suitable areas for macadamia in the 2050s. The results of the soil fertility analysis indicate suboptimal fertility among the sampled macadamia farms. The majority of the soils are strongly acidic and deficient in essential nutrients required for the healthy growth of macadamia trees. Moreover, the average cation exchange capacity (1.67 cmol (+) kg-1) and the soil organic matter content (≤ 1%) are below the minimum optimal levels required for macadamia trees. These findings indicate that soil fertility is one of the primary limiting factors to the crop's productivity, even in areas with suitable climatic conditions. Therefore, addressing the soil fertility issues is crucial to improving the land suitability of the smallholder farms for macadamia, which can lead to optimal yields. This study extends the frontiers of knowledge concerning the macadamia subsector in Malawi by providing insights into the smallholder macadamia farming systems, including demographics, cultivar preferences, and production constraints. It also provides novel empirical evidence on the climate factors that influence the suitability of rainfed macadamia cultivation and identifies current and future suitable growing areas in the country. Additionally, the study addresses the research gap on the soil fertility status of Malawian smallholder macadamia farms. Therefore, the findings of this research have practical implications for various areas such as macadamia cultivar introductions and breeding, land use planning, soil fertility management, and policy formulation for agricultural extension services, inputs, and marketing of the crop.

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