Influence of sewage water on soil chemical properties and yield of Okra

Abstract

Field experiment was conducted with an objective of utilizing sewage water as a source of irrigation on Okra and to know its effect on soil properties. Sewage water of both treated and untreated are obtained from the university campus. The crop was irrigated using Normal Water (NW), Treated Sewage Water (TSW) and Untreated Sewage Water (UTSW) alone and in conjunctive mode constituting nine treatments replicated thrice using RCBD design. Major nutrient constituents in treated and untreated sewage water were higher compared to the normal water. Electrical conductivity and sodium content of UTSW was high (1.67 dS m-1 and 8.70 meq L-1 respectively) compared to TSW (1.67 dS m-1 and 8.70 meq L-1 respectively) and NW (1.67 dS m-1 and 8.70 meq L-1 respectively) but found below the threshold level. Carbonates, bicarbonates, BOD, COD, SAR,RSC and TDS (7.80 mg L-1, 28.70 mg L-1,70.50 mg L-1,151.30 mg L-1,4.58 mg L-1,29.30 mg L-1 and 760.40 mg L-1) was high in UTSW compare to the TSW and NW but did not qualify to cause salt hazards. The results showed that the soil irrigated with TSW and its conjunctive mode led to a significant increase of available nitrogen (270.89, 270.14, 269.47 kg ha-1), available phosphorous (50.76, 48.12, 42.87 kg ha-1) and available potassium (180.42, 178.82, 176.58 kg ha-1) in comparison with NW with decrement in pH values. Treatment receiving only UTSW significantly increased the electrical conductivity (0.19 dS m-1) and sodium content (16.66 mg 100-1) in soil as compared to TSW and NW. Application of treated sewage water registered significantly highest fruit yield (32.35 t ha-1) followed by application of one time normal water fb two times treated sewage water (29.24 t ha-1) and normal water fb treated sewage water applied alternatively (28.12 t ha-1).