Rice variety and sustainable farming: A case study in the Mekong Delta, Vietnam

The Mekong Delta (MKD) produces more than half of the total rice production in Vietnam. In the context of climate change, the Vietnamese government has implemented a development strategy for rice production in the MKD region to improve quality and reduce greenhouse gas emissions. The proportion of aromatic and high-quality rice production is gradually increasing to satisfy the export market. However, there is still an over-reliance on agrochemicals and the impact of overall efficiency of major rice groups is not well understood. This study measures the overall efficiency (OE) and input slacks of rice production in the MKD and considered low-emission rice farming. Using primary survey data from 380 households, the super-slack based measure (super-SBM) in data envelopment analysis (DEA) was employed to calculate the efficiency scores and non-radial slacks of each farm. The results indicated that both aromatic rice (AR) and high-quality rice (HR) groups achieved higher OE in the autumn-winter (AW) season than in the summer-autumn (SA) season. In addition, OE also increased in paddy farms greater than two hectares and in households that have cooperative membership and practice climate smart agriculture (CSA). For the input reduction strategies based on slacks, it was found that each rice group should have the seed density reduced by amounts ranging from 29 to 45 kg/ha. N fertilizer should also be reduced by 33 kg/ha and 35 kg/ha in the SA and AW seasons, respectively. It was estimated that rice farming can correspondingly mitigate N2O emissions by 62−74.2 kg/km2 in the SA season and 64.7−73 kg/km2 in the AW season. Overall, the super-SBM model was effective in simultaneously estimating the overall efficiency and input overuse among paddy fields. In addition, the ranking of "super-efficient" rice farms also supports the restructuring policy of the government in establishing AR and HR production areas for export. Among the adaptation strategies, households that practice CSA techniques have smaller slacks of N fertilizer and irrigation. Low-emission paddy sector development in the MKD favors AR and HR if the CSA techniques are continuously promoted and strictly monitored by the Vietnamese government.