Ammonia exchange on grasslands in an intensive dairying region in central Japan

作者：Hojito Masayuki^*; Hayashi Kentaro; Matsuura Shoji

来源：Soil Science and Plant Nutrition, 2010, 56(3): 503-511.

DOI：10.1111/j.1747-0765.2010.00466.x

• ammonia flux
• dry deposition
• gradient method
• grassland
• nitrogen flow

In an intensive dairying region, N flow through ammonia (NH(3)) is comparatively important because of a high-N loading condition based on livestock manure. To elucidate part of the N flow in Orchardgrass (Dactylis glomerata L.) and Italian ryegrass (Lolium multiflorum Lam.) dominant cutting grasslands in an intensive dairy farming region in central Japan, the NH(3) flux was measured using a gradient method over 3 years. The 3-year means of the annual balance of NH(3) fluxes as the difference between emission and deposition were -14.4 kg N ha-1 in the manure plot and -18.6 kg N ha-1 in the chemical fertilizer plot, averaging -16.5 kg N ha-1. The balance shows the dominance of NH(3) dry deposition in both plots, indicating that these grasslands acted as a net sink of NH(3), receiving 16.5 kg N ha-1 year-1 of NH(3) from the atmosphere. Applications of chemical fertilizer and composted manure caused temporary NH(3) emissions equivalent to losses of 11.6 and 4.4%, respectively, of the applied NH(4)+-N. A previous study has shown that wet deposition was 18 kg N ha-1 year-1 in this intensive dairy farming region, so atmospheric N input to the grassland was estimated to be 34.5 kg N ha-1 year-1as both dry and wet deposition. This amount equalled 17.3% of the 199 kg N ha-1 year-1 generated locally as manure in the region. Assuming that 25% was selected as a representative NH(3) emission factor from livestock manure, atmospheric deposition of ammoniacal N corresponded to 69.5% of the emitted NH(3) from livestock manure in the study area, indicating that emission and deposition of NH(3) in the area is an important internal flow of the N cycle in this intensive dairying region in central Japan.

• 出版日期2010-6