Session 2: Nitrogen, Green House Gasses and Agricultur

HATANO  R.

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紀要類 (bulletin)Session 2: Nitrogen, Green House Gasses and Agriculturedepartmental bulletin pape

HATANO, R.

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

Mitigation of impact of nitrogen cyclingassociated with agriculture and foodconsumption on regional environments著者 HATANO  R.journal orpublication titleJournal of Integrated Field Sciencevolume 9page range 106-106year 2012-03URL http://hdl.handle.net/10097/54459106Mitigation of impact of nitrogen cycling associated with agriculture and food consumption on regional environmentsR. HATANOResearch Faculty of Agriculture, Hokkaido UniversityConcerns about environmental problems such as water pollution, eutrophication, acidiﬁ cation, air pollution, global warming, ozone layer depletion associated with nitrogen load is increasing. Global nitrogen load associ-ated with agriculture and food consumption is supposed to account for 90% of the total, and there is a large nitro-gen load in Asian countries with the remarkable growth of the population. Using the inventory data concerning the ﬂ ows and stocks of nitrogen in the systems of agriculture and food consumption, and the census data in each province of Japan, the export (E), cycling (C), loss (L) and puriﬁ cation in sewage plants (P) were estimated, and their total is obtained as a total system throughput (TST). The L in-creased with the increase of TST and accounted for 50% of the TST. The L increased with the increase of propor-tions of urban area and upland crop ﬁ eld signiﬁ cantly. And the L also increased with the increase of population, animal excreta, and chemical fertilizer application, and decreased with the increase of nitrogen ﬁ xation signiﬁ -cantly. Stream nitrogen concentration in each province in Japan was estimated by assuming the ratio of stream runoff to net nitrogen input (NNI) of 0.27 and the ratio of stream water discharge to precipitation of 0.75. The NNI is deﬁ ned as the difference between the input and the output of nitrogen in the region, and equals to L+P. The area with the estimated nitrogen concentration higher than 1 mg N L-1, which is the Japanese environmental standard for stream nitrogen concentration, was 66% of the total area of Japan. In that case, 55% of NNI was derived from agriculture, and disposed animal excreta accounted for 14% of L. If all the disposed animal excreta were used to alter chemical fertilizer application, NNI derived from agriculture decreased to 50%, and the area with the nitro-gen concentration higher than 1 mg N L-1 reduced to 31%.N2O emission in each province in Japan was estimated by assuming that NNI not discharged to river is deni-triﬁ ed as N2O+N2 (based on the signiﬁ cant increase of stream bicarbonate runoff with the increase of NNI not discharged to river), and the ratio of N2O/(N2O+N2) of 0.71±0.26 (which was measured for the 84 soil samples with pH of 4.3 to 6.6). The result showed 41% of NNI was estimated to be emitted as N2O. The estimated N2O emissions derived from agricultural ﬁ elds and sewage plants in each province ranged from 2.3 to 32.7 and from 3.0 to 107.1 kgN ha-1 yr-1, respectively. By alteration of chemical fertilizer to disposed animal excreta, the N2O emis-sion was reduced by 19%. These ﬁ ndings suggest that reduction of nitrogen input into agriculture is effectively inﬂ uencing the mitigation of environmental loss from agriculture, and further improvement of self-sufﬁ ciency of food to reduce the loss from sewage plants is required.linity up to 30 mmol L-1 NaCl is more favorable for CH4 emission. The application of gypsum can suppress CH4 emission either in saline or non-saline condition.

Mitigation of impact of nitrogen cycling associated with agriculture and food consumption on regional environments

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Mitigation of impact of nitrogen cycling associated with agriculture and food consumption on regional environments

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