Feasibility of Drain Discharge Under 50 M Lateral Spacing Controlled Subsurface Drainage in Saline Vertisols of TBP Command Area

Surface and subsurface drainage discharge water from irrigated agriculture field is normally varies compared with the quality of the canal water supply as the drain discharge water from different locations or facilities will varied in their quality characteristics. Hence, quality assessment or feasibility studies of drain discharge both in short and long term adoption of both conventional and controlled SSD under different drain spacing is prerequisite for its reuse in crop production and efforts are being made elsewhere for reuse of drainage discharge in crop production. Such, feasibility studies on characterization of drain discharge from different subsurface drainage systems are lacking in TBP command area. Hence, it is proposed to conduct this experiment. A plot experiment was conducted during rabi -2021 at Agricultural Research Station, Gangavati (Karnataka) to study the the characterization of drain discharge water for its reuse as an irrigation water. The experiment was laid out as a conventional and controlled subsurface drainage system (SSD). Among the treatments, the collected water samples from six different sampling stations revealed that, drain discharge under conventional subsurface drainage system (SSD) varied from 3.66 to 0.63 compared to 1.38 to 0.42 mm/day under controlled subsurface drainage system. Electrical conductivity of drain discharge water under conventional SSD varied from 3.89 to 1.24 ds/m as against 1.01 to 0.81 ds/m under controlled SSD respectively. While, salt output was varied from 29.0 to 11.0 under conventional compared to 16.5 to 2.5 kg/ha under controlled SSD system. Finally, the subsurface drainage system drain water samples were not suitable for reuse as irrigation water to paddy in the R/S season as per the classification of irrigation water quality particularly for poorly drained black soils in the TBP command area.