caa a22 4500 47710990X CHVBK 20180405111605.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00011298 doi (NATIONALLICENCE)springer-10.1007/BF00011298 Laboratory measurements and simulations of ammonia volatilization from urea applied to calcareous Chinese loess soils [Elektronische Daten] [M. Roelcke, Y. Han, S. Li, J. Richter] Ammonia volatilization is the major pathway for mineral nitrogen loss in the calcareous soils of the Chinese loess plateau, with maximum losses reaching 50% of the fertilizer-N applied. A volatilization-diffusion experiment was carried out in the laboratory using a forced-draft system and soil columns of 15.5 cm depth. Urea was surface applied at rates of 210 kg N ha-1 to a soil with 10% CaCO3 and a pH of 7.7. The amount of ammonia volatilized as well as the concentration profiles of ammoniacal-nitrogen and soil pH in the upper 50 mm of the soil columns after 4, 7 and 10 days were measured and subsequently modelled. The mechanistic model of Rachhpal-Singh and Nye, originally developed for neutral, non-calcareous soils, was modified to include the pH-buffering action of the soil carbonates. Model parameters were independently determined or taken from the literature. Measured and predicted cumulative NH3 losses agreed very well in the first 10 days following fertilizer application. However, in contrast to the simulations, NH3-volatilization was still proceeding in the experiment even after 13 days, with cumulative losses reaching 60% of the applied N. In addition to the high initial soil pH, the low bulk density and high volumetric air content of the soil columns used for the experiment proved decisive for the high rates of ammonia volatilization, provoking a strong increase in the amount of ammoniacal-N diffusing towards the soil surface as gaseous NH3. The simulations showed that due to the high soil pH, the buffering action of the soil carbonates played a comparatively smaller role. Kluwer Academic Publishers, 1996 ammonia volatilization nationallicence calcium carbonate nationallicence China nationallicence loess nationallicence simulations nationallicence urea nationallicence Roelcke M. Institute of Geography and Geoecology, Technische Universität Carolo-Wilhelmina, Langer Kamp 19 c, D-38106, Braunschweig, Germany aut Han Y. Nanjing Institute of Soil Science, Chinese Academy of Sciences, 210008, Nanjing, P.R. China aut Li S. Department of Soil Science, Northwestern Agricultural University, Yangling, 712100, Shaanxi, P.R. China aut Richter J. Institute of Geography and Geoecology, Technische Universität Carolo-Wilhelmina, Langer Kamp 19 c, D-38106, Braunschweig, Germany aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 181/1(1996-04-01), 123-129 0032-079X 181:1<123 1996 181 11104 https://doi.org/10.1007/BF00011298 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00011298 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Roelcke M. Institute of Geography and Geoecology, Technische Universität Carolo-Wilhelmina, Langer Kamp 19 c, D-38106, Braunschweig, Germany aut NATIONALLICENCE 700 1- Han Y. Nanjing Institute of Soil Science, Chinese Academy of Sciences, 210008, Nanjing, P.R. China aut NATIONALLICENCE 700 1- Li S. Department of Soil Science, Northwestern Agricultural University, Yangling, 712100, Shaanxi, P.R. China aut NATIONALLICENCE 700 1- Richter J. Institute of Geography and Geoecology, Technische Universität Carolo-Wilhelmina, Langer Kamp 19 c, D-38106, Braunschweig, Germany aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 181/1(1996-04-01), 123-129 0032-079X 181:1<123 1996 181 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer