title: Evaluation of N environmental risks on Andosols from an intensive dairy farming watershed using DNDC.
abstract: Manure nitrogen (N) in the livestock sector has become a key driver of environmental change. The denitrification-decomposition (DNDC) model was used to evaluate N pollution strengths on Andosols with intensive dairy manure application in Upper Naka River Watershed, Japan. The calibrated model was capable of predicting Andosol N flows because the simulated soil mineral N content, soil nitrogen oxide (N2O) fluxes, denitrification rate, and crop N uptake matched the patterns and magnitudes of the field observations from a wide range of soil textures, as well as manure management and cropping systems. The simulations showed that current intensive manure application systems caused low crop N use efficiency and a large amount of NO3(-)-N leaching and N2O emission. The crop N use efficiency was 27%-42% and 37%-55% of input N for uplands and paddy rice, respectively. The uplands showed much more serious N environmental pollution risks with N leaching 123-362 kg N ha(-1) yr(-1) and N2O emissions 6.53-11.8 kg N ha(-1) yr(-1) than that in the lowland paddy rice with N leaching 17.4-103 kg N ha(-1) yr(-1) and N2O emissions 0.59-2.77 kg N ha(-1) yr(-1). Forage rice/barley crop systems have high N cleaning capability due to the greater crop N uptake which reached to 304 kg N ha(-1) yr(-1). High precipitation stimulated more NO3(-)-N leaching. Sandy soil also showed higher N leaching and was unsuitable for paddy rice. Slurry application stimulated more N2O emission than compost manure. To mitigate the current high N pollution, the critical N application rate was recommended to be approximately 380, 470, 640, and 390 kg N ha(-1) yr(-1) for loam sand planted with maize/grass, loam soil with maize/grass, forage rice/barley, and rice/fallow with winter manure application, respectively.
authors: School of Environment, Tsinghua University, Beijing 100084, China; United Graduate School of Agriculture Science, Tokyo University of Agriculture and Technology, Fuchu 183-8509, Japan. Electronic address: meihuad@163.com.
authors: Meihua
authors: M
authors: Deng
authors: United Graduate School of Agriculture Science, Tokyo University of Agriculture and Technology, Fuchu 183-8509, Japan.
authors: Sonoko D
authors: SD
authors: Bellingrath-Kimura
authors: School of Environment, Tsinghua University, Beijing 100084, China.
authors: Lin
authors: L
authors: Zeng
authors: Field Science Center, Kitasato University, Aomori, Japan.
authors: Masayuki
authors: M
authors: Hojito
authors: School of Environment, Tsinghua University, Beijing 100084, China.
authors: Tianzhu
authors: T
authors: Zhang
authors: United Graduate School of Agriculture Science, Tokyo University of Agriculture and Technology, Fuchu 183-8509, Japan.
authors: Muneoki
authors: M
authors: Yoh
mesh_terms: D003612:Dairying; D004784:Environmental Monitoring; D007564:Japan; D008956:Models, Chemical; D009584:Nitrogen / Q000032:analysis; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D009584:Nitrogen
keywords: Andosol; DNDC; Intensive dairy farming; N environmental pollution; Paddy rice; Upland