Inefficiency model estimation results.

The impact of land tenure security on smallholder crop productivity in Sub-Sahara Africa (SSA) is inconclusive. In Zambia, maize production which serves to satisfy national food security requirements and the generation of foreign exchange from maize exports to regional markets is a big challenge, whereby the majority maize producers are smallholders under an insecure customary land tenure system. We employed an endogeneity-robust stochastic production frontier (SPF) framework to examine the effect of land tenure security on technical efficiency (TE) for smallholder maize producers in Zambia’s Central province. Synthetic Minority Oversampling Technique (SMOTE) was used to treat sample class imbalance between Title Deed Certificate (TDC) holders and non-holders. Our main findings show that use of land on TDCs, including that on customary land tenure types, such as chief-authorized and inherited land had significant impacts on mean TE expansion for smallholder maize production. The production function showed that only chemical fertilizer had a significant positive marginal effect on maize output under drought conditions. Use of oxen helped to expand average maize output. A 90.15% average TE implied that only a small maize output improvement was still possible, using same inputs and technology, under same climatic conditions. We associated the 3–4 ha TE dip with productive capacity transition from subsistence to market-oriented farming. For policy improvements, we recommended the legal recognition of some customary land tenure types, alongside TDC issuances. Lastly, we recommended the expansion of smallholder fertilizer support, and scale efficiency improvement, including minimum land use rate legislation, for eventual maize output expansion in Zambia.撒哈拉以南非洲 (Sub-Sahara Africa, SSA) 地区土地保有安全性对小农作物生产率的影响尚未形成一致研究结论。在赞比亚，玉米生产既要满足国家粮食安全需求，又需通过向区域市场出口玉米获取外汇，这是一项重大挑战——该国绝大多数玉米生产者为小农，且其土地保有制度属于不安全的习惯土地保有体系。本研究采用可解决内生性问题的稳健随机生产前沿 (stochastic production frontier, SPF) 分析框架，考察土地保有安全性对赞比亚中部省份小农玉米生产者技术效率 (technical efficiency, TE) 的影响；同时采用合成少数类过采样技术 (Synthetic Minority Oversampling Technique, SMOTE)，处理土地所有权证书 (Title Deed Certificate, TDC) 持有者与非持有者之间的样本类别失衡问题。核心研究结果表明，持有土地所有权证书的土地使用行为，包括酋长授权土地、继承土地等习惯土地保有类型的土地使用，均对小农玉米生产的平均技术效率提升具有显著正向影响。生产函数分析显示，在干旱条件下，仅化肥对玉米产量具有显著正向边际效应；役牛的使用有助于提升玉米平均产量。研究测得的平均技术效率为90.15%，这意味着在相同投入、相同技术水平与相同气候条件下，仅需小幅优化即可进一步提升玉米产量。研究将3-4公顷种植规模对应的技术效率下降，归因于小农生产从自给自足向市场化农业转型的产能过渡阶段。针对政策优化，本研究建议在发放土地所有权证书的同时，对部分习惯土地保有类型予以法律认可；此外，建议扩大对小农的化肥支持力度，同时提升规模效率，包括出台最低土地使用率相关立法，以最终推动赞比亚玉米产量增长。