Effect of nitrogen fertilizer management and waterlogging on nitrous oxide emission from subtropical sugarcane soils

摘要

Considerable potential for NO emission from Australian sugarcane systems exists from high N fertilizer application rates and periodic waterlogging. To determine NO emissions, 2 experiments were conducted on ratooned sugarcane grown under field conditions. In the first experiment, crops received 0, 100 or 200kgNhap# as single or split application. In the second experiment, a sub-set of the single N application plots was subjected to waterlogging. Higher NO emissions (350og-17mgNOmpo hp#) occurred during warm and wet months (November-February) and coincided with high availability of mineral N in top soil (10-500mgNkgp# soil). Lower emissions (<350ogNOmpo hp#) were detected in cool and dry months (March-October) coinciding with availability of low mineral N (<10mgNkgp# soil). Regression analysis showed significant positive correlations between NO emissions and soil temperature, water-filled pore space and mineral N (ammonium and nitrate) content. NO emissions, soil mineral N content and crop yield followed N application rates (0<100<200kgNhap#) and waterlogging amplified NO emission. Split application of N fertilizer reduced annual NO emissions in the 200kgNhap# treatment. We estimate, using the IPCC Tier 1 approach that between 1.0% and 6.7% of applied N fertilizer was emitted as NO. Our study demonstrates that immediate reduction of NO emissions can be achieved by avoiding high levels of soil mineral N pools and waterlogging through appropriate fertilizer rates and time of application and soil management.