Temporal and Spatial Variations in N₂O Emissions from a Chinese Cabbage Field as a Function of Type of Fertilizer and Application

Author： Cheng Weiguo Sudo Shigeto Tsuruta Haruo Yagi Kazuyuki Hartley Anne

Publisher： Springer Publishing Company

ISSN： 1385-1314

Source： Nutrient Cycling in Agroecosystems, Vol.74, Iss.2, 2006-02, pp. : 147-155

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Abstract

We conducted a field experiment in an Andosol near Tsukuba (Japan) to study the effects of the type of nitrogen fertilizer on nitrous oxide (N₂O) emissions and on nitrogen uptake by Chinese cabbage (Brassica campestris L.). We used four treatments: fertilizer containing no nitrogen (CONT), broadcast application of urea (BR-U), band application of urea (B-U), and band application of controlled-release urea (B-CU). The application rate was 250 kg N ha⁻¹, a conventional rate in the region. We measured N₂O flux two or three times a week during the 82-day growth period, then divided the cumulative emissions into three stages: early (28 days), middle (27 days), and late (27 days). The temporal variation in N₂O emissions differed among the treatments. Broadcast urea application produced 70% of N₂O emissions during the early stage. N₂O emissions increased with increasing cabbage growth in the CONT treatment, indicating that plant growth accompanied by increasing root biomass could stimulate N₂O emissions from unfertilized soil. There were no differences in the patterns of temporal variation in N₂O flux between the two band applications (B-U and B-CU); N₂O emissions in the early and middle stages were 46 and 42%, respectively, for B-U, vs. 41 and 40% for B-CU. However, the overall N₂O emission was reduced by 40.5% in the B-CU treatment compared with the B-U treatment. N₂O emissions from the soils within fertilized bands were dramatically higher than those between the fertilized bands, and this trend continued until harvesting.