Cowpea covers the largest area of any grain legume in Africa and is especially important in West Africa where Nigeria and Niger alone account for over 75% of the total cowpea production in the world. Despite successes of international and national cowpea improvement research in the development and release of several improved varieties, there is limited empirical evidence of adoption and ex‐post impacts of improved cowpea. Using a nationally representative survey data from a sample of 1,525 cowpea‐growing households in northern Nigeria cultivating over 2,500 cowpea plots, we assess the adoption and impacts of improved cowpea varieties on cowpea yields, net returns and production costs. We apply a control function approach and propensity score matching models to estimate the causal effects of adoption of improved cowpea varieties. Our results show that 38% of the cowpea plots were planted with improved varieties, and cowpea yields, net returns and production costs increase significantly with the adoption of improved cowpea varieties. Adoption of improved cowpea varieties is associated on average with 26% yield gains, 61% increase in net returns and 14% increase in production costs. We also show that farmers who have a lower propensity to adopt improved cowpea varieties also face higher costs of production.

中文翻译：

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尼日利亚改良Cow豆品种的采用和事后影响对生产力和净回报的影响

pea豆覆盖非洲所有豆类作物中面积最大的地区，在西非尤为重要。在西非，仅尼日利亚和尼日尔就占世界cow豆总产量的75％以上。尽管国际和国内cow豆改良研究在开发和释放几种改良品种方面取得了成功，但实证证据表明，改良cow豆的采用和事后影响都没有。利用全国代表性的调查数据，该数据来自尼日利亚北部1,525个cow豆种植户的样本，种植了2,500多个cow豆田，我们评估了改良cow豆品种的采用及其对cow豆产量，净收益和生产成本的影响。我们应用控制函数方法和倾向得分匹配模型来评估采用改良cow豆品种的因果效应。我们的结果表明，38％的cow豆地块种植了改良品种，并且采用改良的cow豆品种使cow豆的产量，净收益和生产成本显着增加。采用改良的cow豆品种平均可增加26％的产量，增加61％的净收益和14％的生产成本。我们还表明，倾向于采用改良cow豆品种的农民也面临较高的生产成本。