@article{oai:rakuno.repo.nii.ac.jp:00000394,
 author = {KATAYANAGI, Nobuko and SAWAMOTO, Takuji and 澤本, 卓治 and HAYAKAWA, Atsushi and HATANO, Ryusuke},
 issue = {4},
 journal = {Soil science and plant nutrition},
 month = {Aug},
 note = {Article, To develop an advanced method for estimating nitrous oxide (N_2O) emission from an agricultural watershed, we used a closed-chamber technique to measure seasonal N_2O and nitric oxide (NO) fluxes in cornfields, grassland, pastures and forests at the Shizunai Experimental Livestock Farm (467 ha) in southern Hokkaido, Japan. From 2000 to 2004, N_2O and NO fluxes ranged from -137 to 8,920 µg N m<−2> h<−1> and from -12.1 to 185 µg N m<−2> h<−1>, respectively. Most N_2O/NO ratios calculated on the basis of these N_2O and NO fluxes ranged between 1 and 100, and the log-normal N_2O/NO ratio was positively correlated with the log-normal N_2O fluxes (r^2 = 0.346, P < 0.01). These high N_2O fluxes, therefore, resulted from increased denitrification activity. Annual N_2O emission rates ranged from -1.0 to 81 kg N ha<−1> year<−1> (average = 6.6 kg N ha<−1>). As these emission values varied greatly and included extremely high values, we divided them into two groups: normal values (i.e. values lower than the overall average) and high values (i.e. values higher than average). The normal data were significantly positively correlated with N input (r^2 = 0.61, P < 0.01) and the “higher” data from ungrazed fields were significantly positively correlated with N surplus (r^2 = 0.96, P < 0.05). The calculated probability that a high N_2O flux would occur was weakly and positively correlated with precipitation from May to August. This probability can be used to represent annual variation in N_2O emission rates and to reduce the uncertainty in N_2O estimation.},
 pages = {662--680},
 title = {Nitrous oxide and nitric oxide fluxes from cornfield, grassland, pasture and forest in a watershed in Southern Hokkaido, Japan},
 volume = {54},
 year = {2008}
}