Rescheduling fertilizer nitrogen topdressing timings for improving productivity and mitigating N₂O emissions in timely and late sown irrigated wheat (Triticum aestivum L.)

ABSTRACT

Three-year multi-location field experiments were conducted in soils of varying inherent nitrogen (N) supply in diverse agro-climatic zones for improving productivity and mitigating N₂O emissions in timely sown and late sown wheat. The biomass, total N uptake (TNU) and spectral properties were monitored at different growth stages. Biomass production and TNU statistics of only 0.76% and 3.4%, respectively, till Zadoks 14 growth stage (four leaves stage) revealed that applying all fertilizer N dose by Zadoks 14 is not an appropriate strategy to assure fertilizer N supply throughout the growth stages. Rescheduled fertilizer N topdressings with moderate N (25 kg ha⁻¹) at sowing and remaining N dose in two equal splits at Zadoks 14 and Zadoks 29 (main shoot and 9 more tillers) growth stages reduced N₂O and GHG emissions, respectively, by 32.4% and 30.6%. Sustained N supply till grain filling produced an average of 5.1% to 10.5% higher grain yield and 2.1% to 10.5% higher grain protein content. The spectral properties recorded with PAU-LCC and SPAD meter at Zadoks 29 growth stage governed the grain yield response to fertilizer N application and can be used to fine-tune fertilizer N topdressing decisions over a wide range of varieties, locations, sowing timings and environments.

KEYWORDS:

• Fertilizer nitrogen scheduling
• N₂O emissions
• wheat productivity
• recovery efficiency
• spectral properties

Acknowledgements

The authors acknowledge the Directorate of Biotechnology (DBT), GOI and Biotechnology and Biological Sciences Research Council (BBSRC), UK for funding the study.

Disclosure statement

The authors declare that they have no potential conflict of interest.

Additional information

Funding

The research was jointly funded by the DBT, GOI and BBSRC, UK under the international multi-institutional collaborative research project entitled "Cambridge-India Network for Translational Research in Nitrogen (CINTRIN)" vide DBT Grant No.: BT/IN/UK-VNC/42/RG/2014-15; BBSRC Grant No.: BB/N013441/1.