Nutrient Management Research Database

No-till farming in wheat is being practiced in the rice–wheat system of the Indo-Gangetic plains of south Asia for resource conservation. No-tillage leads to mitigation of carbon dioxide emission, but may emit more nitrous oxide (N₂O) as compared to conventional tillage reducing mitigation benefit. The aim of this study was assessment of N₂O emission in wheat grown under conventional and no-tillage and its mitigation using two new nitrification inhibitors, viz. S-benzylisothiouronium butanoate (SBT-butanoate) and S-benzylisothiouronium furoate (SBT-furoate). Cumulative emission of N₂O-N was higher under no-tillage by 12.2% with urea fertilization and from 4.1 to 4.8% for the inhibitor treatments as compared to the conventional tillage. In no-tillage total emission of N₂O-N reduced from 0.43% of applied N with urea to 0.29% of applied N with SBT-furoate treatment. The N₂O-N emissions in SBT-butanoate treatment were at par with the standard dicyandiamide (DCD) inhibitor treatment. Water-filled pore space (WFPS) was higher on most days under no-tillage, with the largest emissions (>1000 μg N₂O-N m⁻² day⁻¹) coming with nitrification of ammonium-N present in soil below 60% WFPS. Carbon efficiency ratio was highest (48.1) from SBT-furoate treatment under conventional tillage. The nitrification inhibitors used in the study increased yield of wheat, reduced global warming potential by 8.9–19.5% over urea treatment and may be used to mitigate N₂O emission.

This study examined the effects of three nitrification inhibitors and conventional tillage vs. no tillage on nitrous oxide (N2O) emissions in a rice-wheat system.

The nitrification inhibitors studied were SBT-butanoate, SBT-furoate, and dycyandiamide (DCD).

Urea was applied at a rate of 108 lbs N/ac, split into 3 applications of 54, 27, and 27 lbs N/ac at 20, 40, and 87 days after sowing of wheat.

All three nitrification inhibitors were applied at 10% of the total N added.

Tillage

No tillage treatments showed higher N2O emissions, with and without urea fertilization. This can be attributed to the higher moisture content and compaction under no-till.

Nitrification Inhibitors

All nitrification inhibitors reduced N2O emissions. However, the reductions differed based on which inhibitors was used.

DCD and SBT-butanoate reduced emissions by about 9% while SBT-furoate reduced emissions by 13.5%.