Impact of government intervention to maize efficiency at farmer’s level across time: a robust evidence in Northern Vietnam

The Vietnamese government has already legislated many agricultural policies to improve farmers’ performance. In particular, the extension programme aims to enhance technical efficiencies of targeted farmers. Besides, negative environmental effects of chemical pesticides and climate change on agricultural production efficiency have been proved in many recent studies. Therefore, the northern mountainous areas of Vietnam have not exceptionally been omitted from all discussions. This article examines the impact of government intervention by applying difference-in-difference method to determine the change in maize farmers’ technical efficiency using farm survey data of 666 northern maize farmers in the period of 2010 and 2015. Firstly, cultivation land was found to have a fundamentally significant effect on both trained and non-trained farmers. The extension programme has resulted in an ambiguous outcome, but the spillover effects of extension knowledge successfully spread out among all trained farmers to simultaneously increase. Furthermore, overexploited pesticides of either trained or non-trained farmers were altered since the introduction of extension in survey areas. The determinants of maize technical efficiency were analysed following a robust truncated half-normal regression. DID estimator signifies that although trained farmers achieved 95.6% averagely, which is considerably higher than that of non-trained group (88.1%) after 5 years, the increment pace of non-trained farmers was slightly higher at 0.031%. The environmental factors, such as the rise of temperature and the reduction in precipitation, had a negative significant impact on farmers’ technical efficiency. Adaptive measures to climate change should be considered to simultaneously enhance the technical efficiency of maize farmers.