Nitrate leaching, nitrous oxide emission and N use efficiency of aerobic rice under different N application strategy

ABSTRACT

A field study was conducted in the sub-humid tropical region of India to examine the effect of different nitrogen (N) management strategies on nitrate leaching, nitrous oxide (N₂O) emission and N use efficiency in aerobic rice. Treatments were: control (no N), 120 kg N ha⁻¹ applied as prilled urea (PU) in conventional method, 120 kg N ha⁻¹ applied as neem coated urea (NCU) in conventional method, N applied as PU on the basis of leaf colour chart (LCC) reading, N applied as NCU on the basis of LCC reading, and 120 kg N ha⁻¹ applied as PU and farm yard manure (FYM) in 1:1 ratio. Results showed that 3.4–16.1 kg NO₃-N ha⁻¹ was leached below 45 cm depth and 0.61–1.12 kg N₂O-N ha⁻¹ was emitted from aerobic rice during the growing season. NCU when applied conventionally reduced nitrate-nitrogen (NO₃-N) leaching and N₂O emission by 18.6% and 21.4%, respectively However when applied on the basis of LCC reading NCU reduced NO₃-N leaching by 39.8% as compared to PU applied in conventional method. NCU when applied on the basis of LCC reading synchronized N supply with demand and reduced N loss, which resulted in higher yield and N use efficiency.

KEYWORDS:

• NO₃ leaching
• N₂O emission
• nitrogen use efficiency
• aerobic rice
• leaf colour chart

Acknowledgments

The work has been done under NRRI plan project and partly supported by the grant of National Innovations on Climate Resilient Agriculture (NICRA), ICAR, New Delhi. Technical support provided by the Mr. Bhabesh Chandra Pradhan and technical staff of the Division of Crop Production, NRRI is acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Innovations on Climate Resilient Agriculture (NICRA), ICAR, New Delhi.