Residu Nitrogen dan Fosfat di Sungai Panasen Hulu Daerah Aliran Sungai Tondano Kurun Waktu (2013-2020)

Nitrogen and phosphate fertilizer residues in the upstream of Tondano watershed have the potential to enter Lake Tondano since the water body empties into Lake Tondano thus their residues that are not absorbed by plants will cause residual impacts in the waters of Lake Tondano. The purpose of this study was to monitor the concentration of nitrogen and phosphate residues in the upstream of the Tondano watershed for a period of 8 (eight) years (2013-2020). The method of research is field observations of agricultural activities and water quality sampling carried out using the composite sampling method in the Panasen River which is the outlet of the irrigation channel upstream of the Tondano watershed. Data analysis using Spectrophotometric Method and comparing with the Quality Standard according to PP. 22/2021 Appendix VI, Class II. Results were compared with the water quality standard according to Government Regulation No. 22/2021 Appendix VI, Class II. This research showed that concentration of nitrogen residue (nitrate) 0.069-0.966 mg/l meets the quality standard (quality standard for nitrate 10 mg/l); nitrite concentration 0.001-0.61 mg/l (Quality standard nitrite 0.06 mg/l); phosphate concentration 0.084 mg/l-1.21 mg / l (phosphate quality standard 0.2 mg / l) planting season in 2013-2020. The tendency of nitrogen and phosphate residues to increase in March, June and September is the time for fertilization