Effect of direct and residual sewage-sludge application on physiological attributes of rice-wheat cropping system

An experiment was conducted to assess the growth and yield attribute of rice–wheat cropping system (RWCS) as influenced by conjoint application of treated sewage sludge (TSS) and fertilizer at Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India, from June 2017 to May 2019. The treatments comprised:  control, 100% RDF recommended dose of nitrogen (N), phosphorus (P) and potassium (K), 100% RDF + 20 t ha-1 TSS, 100% RDF + 30 t ha-1 TSS, 50% RDF + 20 t ha-1 TSS, 60% RDF + 20 t ha-1 TSS, 70% RDF + 20 t ha-1 TSS, 50% RDF + 30 t ha-1 TSS, 60% RDF + 30 t ha-1 TSS, 70% RDF + 30 t ha-1 TSS. The experiment was laid-out in randomized block design with three replications. The result of our study indicated that higher growth parameter (plant height, greenness index and tillers), yield attribute (length of panicle/ear, grain par panicle/ear) and yield of rice and wheat were recorded under 100% RDF with 20 and 30 t SS ha-1 as compared to 100% RDF alone. However, 70% RDF+ 30 t SS ha-1 had given equivalent or higher yield than 100% RDF in RWCS. Our results suggested that in short term application of sewage sludge would provide higher yield without any harmful/negative impact on environment. On the other hand, if the goal is efficient and economic use of fertilizer with greater sustainability, use as of 70% RDF with 20 and 30 t ha-1 SS as organic amendment can be recommend.