Abstract Recent agricultural transformation in Asia and Africa has witnessed the gradual spread of mechanization in agricultural areas that are still largely made up of smallholder farming. While the literature has often characterized mechanical technologies as being complementary to land, knowledge gaps exist with regard to the process of adoption of mechanization by smallholders for whom the scope for exploiting its complementarity with land is limited. We test a hypothesis that yield-enhancing biological technologies—which potentially raise total factor productivity and returns to more intensive farm-power use—are important drivers of the adoption of agricultural mechanization among smallholders. To enhance the external validity of evidence, we empirically analyze this hypothesis by applying the same methodologies in two countries, lowland (Terai) Nepal and Ghana. We employ nationally representative, repeated, cross-sectional data from both countries, as well as unique tractor-use data from Ghana; we also employ multidimensional indicators of agroclimatic similarity in the respective plant breeding locations. We show that in both lowland Nepal and Ghana, the adoption of tractors and agricultural equipment has been induced by yield-enhancing biological technologies, particularly improved varieties and high-yielding production systems, when these biological technologies are instrumented by agroclimatic similarity to plant breeding locations, which is measured accounting for the multidimensional characteristics of agroclimatic conditions, and thus proxies spillover potentials of the public sector developed biological technologies. In general, these effects are particularly strong among smaller farms, and the effect holds for the adoption of mechanization both at extensive margins (whether to adopt) and at intensive margins (how much to adopt). In Ghana, partly due to improved efficiency in supply-side factors of mechanization, these linkages have strengthened in the 2010s. The results suggest that in both countries, mechanization support strategies for smallholders can potentially improve their targeting by utilizing the information of agroclimatic similarity with plant breeding locations. In Ghana, further public investments in plant-breeding system in strategic locations may broadly enhance smallholders' demand for mechanization. In lowland Nepal where tractor adoptions have grown fairly high, it is now important to more carefully evaluate the trade-off between smallholder-based growth strategies and other strategies, for example, promoting scale-expansions of farming, which also involves mechanization.

中文翻译：

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提高产量的生物技术引发的小农机械化：来自尼泊尔和加纳的证据

摘要 亚洲和非洲最近的农业转型见证了机械化在仍主要由小农农业组成的农业地区的逐步普及。虽然文献经常将机械技术描述为对土地的补充，但在利用机械化与土地互补性的范围有限的小农采用机械化的过程方面存在知识差距。我们检验了一个假设，即提高产量的生物技术——有可能提高全要素生产率并回归更集约的农业用电——是小农采用农业机械化的重要驱动力。为了提高证据的外部有效性，我们通过在两个国家应用相同的方法对这一假设进行实证分析，低地（Terai）尼泊尔和加纳。我们采用来自两国的具有全国代表性的重复横断面数据，以及来自加纳的独特拖拉机使用数据；我们还在各自的植物育种地点采用了农业气候相似性的多维指标。我们表明，在尼泊尔低地和加纳，拖拉机和农业设备的采用是由提高产量的生物技术引起的，特别是改良品种和高产生产系统，当这些生物技术通过与植物育种地点的农业气候相似性进行检测时，这是衡量农业气候条件的多维特征，因此代理公共部门开发的生物技术的溢出潜力。一般来说，这些影响在较小的农场中尤为明显，这种影响适用于在粗放边际（是否采用）和集约边际（采用多少）的情况下采用机械化。在加纳，部分由于机械化供应方因素的效率提高，这些联系在 2010 年代得到加强。结果表明，在这两个国家，针对小农的机械化支持战略可以通过利用与植物育种地点的农业气候相似性信息来潜在地提高他们的目标。在加纳，进一步对战略地点的植物育种系统进行公共投资可能会广泛提高小农对机械化的需求。在拖拉机收养率相当高的尼泊尔低地，