Influence of organic amendments and different levels of nitrogen on production potential, economics and energetics of rice (Oryza sativa)–wheat (Triticum aestivum) cropping system

A field experiment was conducted during 2018–19 and 2019–20 at the Punjab Agricultural University, Ludhiana and Research Station, Dyal Bharang, Amritsar, to study the influence of organic amendments and nitrogen levels on rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system. In rice, main plot treatments were green manuring (GM), farmyard manure (FYM), poultry manure (PM) and control (NA). Nitrogen levels in sub-plots comprised control (N1), 50 kg N/ha (N2),75 kg N/ha (N3) and 100 kg N/ha (N4). In wheat, residual effect of organic amendments and nitrogen levels applied to preceding rice was evaluated. The statistically highest grain yield of rice was obtained with PM (8.29 t/ha), followed by GM (8.02 t/ha) which was at par with FYM (7.90 t/ha). The lowest rice grain yield was obtained with NA (5.16 t/ha) and its subsequent wheat crop recorded significantly higher grain yield with PM (6.14 t/ha), followed by FYM (5.88 t/ha) and GM (5.72 t/ha). Treatment N4 recorded significantly higher yield than N2 and was at par with N3. Maximum rice-equivalent yield (14.7 t/ha) was recorded with PM, while the highest energy-use efficiency of rice was recorded with green-manure (16.2) as compared to the other treatments. Treatment with the application of PM and N4 recorded significantly the highest economic parameters and system productivity for both rice and wheat crops compared to rest of the treatments.