Effects of subsidy and regulation policy on soil and water resources of cotton planted lands in Harran Plain, Turkey

Cotton (Gossypium hirsutum L.) provides essential raw material used in the textile, feed, and vegetable oil sectors. Therefore, it is a strategic crop for agricultural, economic, and political strategies around the world. Accurate monitoring of the changes in the cotton production patterns is crucial for decision-makers. Turkey is among the top ten cotton producers and ranks fourth in the world for cotton imports. One third of the total cotton pro-duction in Turkey comes from the southeastern Anatolia region of the country. This study analyzed the impact of subsidy and regulation policies on fluctuations in cotton production areas and soil and water quality in Harran Plains, southeastern Anatolia region Turkey. Time-series (between 2016 and 2021) satellite images were utilized to determine actual crop rotation in the study area. Turkish Government implemented a new rule for crop subsidies in 2020 which stated that a farmer will be eligible for subsidy for two consecutive years; however the subsidy will not be paid if the same crop is planted in the third year. Cotton was cultivated in 83 % of the Harran plains prior to new subsidy regulation, which decreased to 26 % after the new regulation. Sudden decrease in cotton cultivation area clearly indicated that farmers need public support to cover the costs in agricultural production. The Gross Production Value (BPV) for each crop was calculated to determine the impact of subsidy regulation on economic value of crops in the rotation.The GPV in 2020 was 2.903,7 $ ha(-1) that was 33.6 % and 20.5 % lower than 2019 and 2021, respectively. The results indicated that crop subsidies significantly altered the crop selection behavior of farmers. Water requirement of crops in rotation between 2016 and 2021 was calcu-lated to assess the effects of subsidy changes on water consumption. Cotton cultivation over a large part of the plains during the same season caused excessive water consumption, rise in groundwater level over time, soil salinity and severe water erosion. However, cotton cultivation area as well as water consumption in Harran plain new significantly decreased with the new subsidy regulation; therefore, water consumption in 2020 was the lowest among the time frame evaluated. Total sediment losses through surface runoff from the Harran Plain was estimated as 0.83 tons ha(-1) per year. The results revealed that subsidies exert significant impacts on the gross production value in the region, amount of irrigation water consumed, and quality of soil and water resources in addition to the impact on the decision of farmers for crop selection.

Automated summary

Turkey plays a significant role in the global cotton production and import, and this study analyzed the fluctuations in cotton production and soil and water quality in the Harran Plains region of southeastern Anatolia. The results showed that subsidy and regulation policies had significant impacts on crop selection behavior, decreasing cotton cultivation area and water consumption. However, these policies also affected the gross production value, water resources, and soil quality in the region.