Determination of eco-efficiency and optimization of input utilization in hazelnut production of Türkiye

The heavy reliance on input use in hazelnut production not only reduces economic efficiency but also threatens environmental sustainability, highlighting the need for improved input management and reduced ecological impact. This study aimed to assess the eco-efficiency of hazelnut farms using an input-oriented inverse DEA approach, determine the optimal input levels, and identify the factors contributing to eco-inefficiency through truncated regression analysis. Primary data were collected from 121 hazelnut farms through face-to-face interviews in the provinces of Giresun, Ordu, and Samsun in Türkiye. The inverse DEA method was used to evaluate eco-efficiency, while the truncated regression model was used to identify factors contributing to eco-inefficiency. The results revealed that the highest greenhouse gas (GHG) emissions in hazelnut production were caused by pesticides, contributing 153.58 kg CO2-eq of GHG emissions per hectare. This was followed by manure at 132.53 kg CO2-eq per hectare, chemical fertilizer at 78.44 kg CO2-eq per hectare, and diesel fuel at 72.66 kg CO2-eq per hectare. The average eco-efficiency score was calculated to be 82.8%, meaning that inputs could be reduced by 17.2% without affecting output. Pesticide use accounted for 24.83% of the total emissions, while manure contributed 21.42%, making them the largest sources of emissions. In hazelnut production, labor input was the most over-utilized resource, accounting for 12.40% of the total, followed by land size at 11.32% and other inputs at 10.53%. The eco-inefficiency model results showed that farming experience was statistically significant at the 10% level, agricultural insurance at the 5% level, and social security at the 1% level. The inefficient use of resources has a negative impact on both the economy and the environment. Therefore, implementing policies that promote the efficient use of inputs will significantly enhance the eco-efficiency of hazelnut production in Türkiye.