Microbial inoculations and nitrogen application to decompose in situ rice residue ameliorate the microclimate and sustainability of Happy Seeder sown wheat in Indian Punjab

The study investigates the impact of different nitrogen management practices and microbial decomposition of rice residue on microclimate, heat utilization efficiency and productivity of Happy Seeder sown wheat. Two locations, i.e. Punjab Agricultural University (PAU), Ludhiana, and University Seed Farm (USF), Ladhowal, Punjab, with different soil textures, were selected for the study during the rabi seasons of 2017–18 and 2018–19. The experiment consisted of six nitrogen management techniques (kg ha⁻¹) in main plots and four treatments of in situ microbial decomposition in sub-plots laid out in split plot design with three replications. The cumulative growing degree days (GDD) and heliothermal units (HTU) were found to be maximum in the treatment where nitrogen was applied @ 150 kg ha⁻¹ preceded by 3% urea spray on in situ rice residue after paddy harvest (N₅). Combined inoculation of Aspergillus sp. + Delftia sp. as consortia (M₄) too cumulated maximum GDD and HTU. Minimum canopy temperature, maximum normalized difference vegetation index (NDVI), yield attributing traits and grain yield prevailed in treatments N₅ and M₃ (Delftia sp.). Treatment N₅ produced 45.6% and 41.6% higher grain yield over control (N₁) at Ludhiana and Ladhowal, respectively. Proper nitrogen management and role of microbial culture in enhancing decomposition of rice residue and the strong correlation between grain yield; and GDD and HTU hold the key to improve resilience in wheat crop for sustainable production under changing climatic scenarios.