成果の概要

Under the SATREPS Madagascar II project, comprehensive field observations and experiments were conducted across four climatically distinct regions of Madagascar to evaluate the effectiveness of localized phosphorus (P) fertilizer application (P dipping), in combination with other fertilizer management practices, on rice productivity and environmental impacts. During the field mission, rice fields that had reached maturity at all study sites were harvested sequentially. Grain yield and shoot biomass samples were collected from each experimental plot and transported to the Radioisotopes Laboratory (LRI) for detailed measurement and analysis. Greenhouse gas (GHG) monitoring was carried out throughout the rice growing season until harvest. Gas samples were collected weekly at all sites, carefully sealed, and transported to Japan for subsequent determination of methane (CH₄) and nitrous oxide (N₂O) concentrations. In addition, grain yield, shoot biomass, and weekly GHG samples were obtained from previously established pot experiments at LRI, which assessed the effects of farmyard manure management on rice growth and GHG emissions across different soil types.