title: Estimating agro-ecosystem carbon balance of northern Japan, and comparing the change in carbon stock by soil inventory and net biome productivity.
abstract: Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959-2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from -1.26MgCha(-1)yr(-1) in 1959-0.26 Mg Cha(-1)yr(-1) in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959-2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods.
authors.affiliation: School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China; Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589, Japan. Electronic address: icy124@hotmail.com.
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.affiliation: Faculty of Agriculture, Ehime University, 3-5-7, Tarumi, Matsuyama 790-8566, Ehime, Japan.
authors.forename: Yo
authors.initials: Y
authors.lastname: Toma
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, Scotland, UK.
authors.forename: Jagadeesh
authors.initials: J
authors.lastname: Yeluripati
authors.affiliation: Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Iwasaki
authors.affiliation: Leibniz Centre for Agricultural Landscape Research, Institute of Land Use Systems, Germany.
authors.forename: Sonoko D
authors.initials: SD
authors.lastname: Bellingrath-Kimura
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Edward O
authors.initials: EO
authors.lastname: Jones
authors.affiliation: Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Hatano
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data*; D057486:Carbon Cycle; D002980:Climate; D017753:Ecosystem; D004784:Environmental Monitoring; D017752:Greenhouse Effect; D007564:Japan; D008962:Models, Theoretical; D012987:Soil
chemical_list: D012987:Soil
keywords: Agriculture; Carbon sequestration; Net biome productivity; Regional scale; Soil inventory; Uncertainty