Yield and Profitability of Rice-Wheat Sequence with Conjunctive Application of Sewage Sludge and Chemical Fertilisers

摘要

Sewage sludge (SS) obtained from wastewater treatment plants has valuable agronomic properties in agriculture. The aim of the study was to find out the effect of one-time application of sewage sludge to rice and its residual effect on yield and yield components of subsequent crops. Field experiments were conducted for two consecutive years taking two crops each of rice and wheat in a sequence. Graded levels of SS were applied alone and along with 50 and 100 recommended dose of fertilisers (RDF). The experiments were conducted in Randomized Block Design (RBD) with 10 treatments taking three replications. During two crops cycle, sewage sludge levels showed significant increase in growth and yield attributing characters. The maximum grain yield in all four crops during two years was recorded in T7 (100 RDF + 45 t ha~(-1) SS), whereas, the minimum was observed in T2 (15 t ha1 SS). Application of 45 t ha"1 SS + 50 RDF in Ist rice and only 50 RDF in subsequent crops resulted significantly higher grain yield in Ist rice and statistically at par yield with RDF in subsequent crops. Application of 30 t ha~(-1) SS along with 50 RDF (T9) produced grain yield statistically at par with RDF (T2) in all the four crops of the sequence. The treatment T7 (100 RDF + 45 t ha~(-1) SS) showed the highest grain yield and net return followed by T6 (100 RDF + 30 t ha1 SS), but the benefitxost ratio (B:C) ratio was maximum for T_(10) (50 RDF + 45 t ha~(-1) SS). Hence the profitability was higher when 45 t ha~(-1) SS was applied with 50 RDF. Sewage sludge application at 30 t ha~(-1) and above led to the accumulation of Cd, Cr, Ni and Pb in postharvest soil samples after two cropping cycles of rice- wheat sequence.