Assessment of Nitrate and Phosphate Concentrations in Discharge Water from Ditch Networks across Different Peatland Use Types: Implications for Sustainable Peatland Use Management

Peat soils, when drained and transformed for different land uses, can release pollutants such as nitrate and phosphate into nearby water bodies and ecosystems through ditch networks. However, there have been limited studies to ascertain the extent and impact of these nutrient releases under various peatland use types. A total of fifty-four water samples were collected between October 2021 and January 2022 from five industrial cutaway bogs, twenty-five grasslands, and twenty-four forest plantations. The water samples were subsequently examined for nitrate–nitrogen and phosphate–phosphorus using the HACH DR890 colorimeter. This study showed that the nitrate–nitrogen concentration of the discharge water ranged from 6.9 mg/L from forestry to 10.52 mg/L from grassland. The phosphate–phosphorus concentration ranged from 0.43 mg/L from forestry to 0.78 mg/L from grassland. The nitrate–nitrogen and phosphate–phosphorus concentrations in the drainage channel exhibited by the grassland and the cutover did not differ significantly (p > 0.05). Upon comparing the results obtained with the established safety limits set by the European Union (EU) and World Health Organization (WHO), it was observed that phosphate–phosphorus and nitrite–nitrogen concentration in the surface water (specifically, discharge water) exceeded the permissible threshold concentrations in surface water. The nutrient pollution index revealed that the discharge water from the ditch networks across the studied peatland use type was highly polluted, with a trend following the order of grassland > cutover > forestry. These results are in line with the broader issue of excessive nutrient inputs in freshwater ecosystems, which can lead to eutrophication. This study promotes sustainable water resources and peatland management practices by determining nitrate–nitrogen and phosphate–phosphorus concentrations in discharge water from ditch networks associated with different peatland use types: grassland, forestry, and cutover. This research emphasizes the critical need for sustainable peatland management to improve water quality in the river basin districts under the Water Framework Directive.