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Titolo:
NITROGEN DEPOSITION AND ITS CONTRIBUTION TO NITROGEN CYCLING AND ASSOCIATED SOIL PROCESSES
Autore:
GOULDING KWT; BAILEY NJ; BRADBURY NJ; HARGREAVES P; HOWE M; MURPHY DV; POULTON PR; WILLISON TW;
Indirizzi:
IACR ROTHAMSTED,DEPT SOIL SCI HARPENDEN AL5 2JQ HERTS ENGLAND
Titolo Testata:
New phytologist
fascicolo: 1, volume: 139, anno: 1998,
pagine: 49 - 58
SICI:
0028-646X(1998)139:1<49:NDAICT>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
ROTHAMSTED-EXPERIMENTAL-STATION; BROADBALK WHEAT EXPERIMENT; UNITED-KINGDOM; DRY DEPOSITION; ATMOSPHERIC DEPOSITION; DIOXIDE CONCENTRATIONS; SURFACE-EXCHANGE; DIFFUSION TUBES; WINTER-WHEAT; NITRIC-ACID;
Keywords:
NITROGEN CYCLING; ATMOSPHERIC DEPOSITION; MINERALIZATION; NITRIFICATION; TRACE GAS FLUXES; AIR POLLUTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
56
Recensione:
Indirizzi per estratti:
Citazione:
K.W.T. Goulding et al., "NITROGEN DEPOSITION AND ITS CONTRIBUTION TO NITROGEN CYCLING AND ASSOCIATED SOIL PROCESSES", New phytologist, 139(1), 1998, pp. 49-58

Abstract

Human activity has greatly perturbed the nitrogen cycle through increased fixation by legumes, by energy and fertilizer production, and by the mobilization of N from long-term storage pools. This extra reactive N is readily transported through the environment, and there is increasing evidence that it is changing ecosystems through eutrophication and acidification. Rothamsted Experimental Station, UK has been involved in research on N cycling in ecosystems since its inception in 1843. Measurements of precipitation composition at Rothamsted, made since 1853, show an increase of nitrate and ammonium N in precipitation from 1and 3 kg N ha(-1) yr(-1) respectively, in 1855 to a maximum of 8 and 10 kg N ha(-1) yr(-1) in 1980, decreasing to 4 and 5 kg N ha(-1) y(-1)today. Nitrogen inputs via dry deposition do, however, remain high. Recent measurements with diffusion tubes and filter packs show large concentrations of nitrogen dioxide of c. 20 mu g m(-3) in winter and c. 10 mu g m(-3) in summer; the difference is linked to the use of central heating, and with variations in wind direction and pollutant source. Concentrations of nitric acid and particulate N exhibit maxima of 1.5and 2 mu g m(-3) in summer and winter, respectively. Concentrations of ammonia are small, barely rising above 1 mu g m(-3). Taking deposition velocities from the literature gives a total deposition of all measured N species to winter cereals of 43.3 kg N ha(-1) yr(-1), 84 % as oxidized species, 79 % dry deposited. The fate of this N deposited to the very long-term Broadbalk Continuous Wheat Experiment at Rothamsted has been simulated using the SUNDIAL N-cycling model: at equilibrium, after 154 yr of the experiment and with N deposition increasing from c. 10 kg ha(-1) yr(-1) in 1843 to 45 kg ha(-1) yr(-1) today, c. 5 % is leached, 12% is denitrified, 30% immobilized in the soil organic matter and 53 % taken off in the crop. The 'efficiency of use' of the deposited N decreases, and losses and immobilization increase as the amountof fertilizer N increases. The deposited N itself, and the acidification that is associated with it (from the nitric acid, ammonia and ammonium), has reduced the number of plant species on the 140-yr-old Park Grass hay meadow. It has also reduced methane oxidation rates in soil by c. 15 % under arable land and 30 % under woodland, and has caused Nsaturation of local woodland ecosystems: nitrous oxide emission ratesof up to 1.4 kg ha(-1) yr(-1) are equivalent to those from arable land receiving > 200 kg N ha(-1) yr(-1), and in proportion to the excess N deposited; measurements of N cycling processes and pools using N-15 pool dilution techniques show a large nitrate pool and enhanced rates of nitrification relative to immobilization. Ratios of gross nitrification:gross immobilization might prove to be good indices of N saturation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/09/20 alle ore 04:04:57