Abstract. Le TL, Luu TTH, Huynh N, Chung RH. 2020. Environmental efficiency of rice production in Vietnam: An application of SBM-DEA with undesirable output. Biodiversitas 21: 2710-2715. In Vietnam, the agricultural sector is one of major sources of the country’s greenhouse gas (GHG) emissions and over half of that comes from rice cultivation. This study evaluates the environmental efficiency of 400 rice farms in the Mekong Delta using slack-based measure (SBM) data envelopment analysis (DEA) with considering the total amount of CO2-equivalent (CO2-eq) emissions in the rice field as undesirable output. The findings revealed that the average environmental efficiency score of the farmers was very low, just only 0.461. Only 2.25% of the sample farms were environmentally efficient while majority of them (58%) obtained the efficiency values less than the mean indicating that their environmental efficiency needs to be further improved. The small rice farms were higher in environmental efficiency scores compared with large farms. The sample rice farmers who are members of agricultural cooperatives obtained a significantly higher environmental efficiency than the non-cooperative members. The estimated results of input and bad output excesses showed that about 1.35 tons of CO2-eq ha-1 could be reduced and an average of 54.18 kg N ha-1 could be saved in order to improve the environmental performance of rice production in the study area.

The Arbuscular Mycorrhiza fungi have a mutualistic relationship with 80% of terrestrial plants. Arbuscular Mycorrhiza fungi are considered as a biofertilizer source because of their positive effects on plant growth andproductivity They can help to reduce the amount of chemical fertilizers by up to 50% due to their ability in enhancing crops to uptake mineral nutrients efficently such as nitrogen, phosphorus, potassium, calcium, zinc. . . thereby increasing crop yield. Moreover, this endosymbiotic fungus also shows its potential as a biopesticide due to its ability to biologically antagonize a wide range of fungi, viruses, and nematodes, which cause diseases on plants. Besides, Arbuscular Mycorrhiza fungi also help plants to resist to abiotic streeses such as drought, salinity, and toxicity of heavy metals. The glomalin compound secreted by mycorrhizal fungi has the ability tobind tiny soil particles together to form a stable soil structure and aggregates, helping to improve soil qualitỵ Thus, Arbuscular Mycorrhiza fungi have a high use potential in sustainable agricultural development under the context of climate change such as drought, salinity intrusion.

Rice farmers do not recognize the negative impacts of overusing agricultural chemicals in farming activities on the environment. Hence, this study aimed to estimate technical and environmental efficiency for the rice producers in Tra Vinh province of Vietnam using the translog stochastic production frontier approach. Nutrients of NPK and pesticide cost were assumed to be environmentally detrimental inputs for environmental efficiency estimation. Empirical results indicated that the mean technical efficiency score was 0.74 showing technical inefficiency in the sample farms. The average environmental efficiency indexes were 0.55 for two detrimental inputs, 0.51 for nutrients of NPK, and only 0.10 for pesticide alone, indicating that the rice farms have huge potential to decrease the use of these inputs. The reduction in fertilizer, especially pesticide use, will help the rice farmers achieve higher profitability and be more sustainable. Regarding determinants of farms’ efficiencies, the regression analysis revealed that participating in agricultural cooperatives has emerged to be a favorable factor associated with technical and environmental efficiency, suggesting that the development of agricultural cooperative models should be prioritized to promote and encourage farmers’ participation. The present study results could be seen as key points for farmers' adjustment in rice production, leading to a safer environment and a driving force in the sustainable agriculture development in the Mekong Delta of Vietnam.