Nutritional status of wastewater irrigated soil under lemongrass (Cymbopogon flexuosus)

Abstract

A field experiment was conducted in a split plot design at ICAR-Indian Agricultural Research Institute (IARI) to evaluate the effects of groundwater (GW), untreated wastewater (WW), constructed wetland treated wastewater (TWW) and groundwater in conjunction with untreated wastewater in cyclic mode (CW) in the main plots and three levels of fertilizers in subplots viz. control (no NPK fertilizer application) (N0), recommended dose of NPK fertilizers – amount of NPK added through irrigation water (N1) and recommended dose of NPK fertilizers (N2) during 2018-2019 on the soil chemical properties. The N, P, K, RSC, Zn, Cu, Mn, Fe, Ni, Pb and Cr contents in untreated wastewater were significantly higher and 2.3, 3.7, 2.7, 1.6, 3.1, 2.0, 2.1, 2.9, 2.3, 7.2 and 2.3 times more than the constructed wetland treated water respectively. The initial soils were normal in reaction having pH 7.34, electrical conductivity 0.29 dSm-1, organic carbon 0.68% and available N, P and K contents were 238, 24.6 and 227 kg ha-1. Similarly, DTPA extractable Zn, Cu, Mn and Fe were well above the deficiency critical limit but below the permissible threshold limit for toxicity. The available Ni, Pb and Cr contents were 0.22, 2.54 and 0.25 mg kg-1. The organic carbon, macro nutrients (N, P, and K) and micronutrients (Zn, Mn, Cu and Fe) content of soil got improved with sewage irrigation followed by soil irrigated alternatively with sewage and ground water. The results demonstrated that raising lemongrass with wastewater improved the nutritional quality of soil.