Nitrogen flows due to human activities in the Cianjur–Cisokan watershed area in the middle Citarum drainage basin, West Java, Indonesia: a case study at hamlet scale

Abstract

This paper demonstrates a methodology to estimate nitrogen flow due to human activities in three rural hamlets located at different elevations in the Cianjur–Cisokan watershed area, West Java, Indonesia. The rural ecosystem in each hamlet was divided into several components and material transfers between components due to human activities were estimated, mainly by interview, and converted to nitrogen. Then a component model of nitrogen flow in each hamlet was constructed. Nitrogen balances of the three hamlets were positive: 87–267 kg N ha−1 per year. Two indices, NSENO (nitrogen surplus per unit edible nitrogen output) and NSEEO (nitrogen surplus per unit edible energy output), were newly proposed. These indices showed that nitrogen surplus of the hamlet with the lowest elevation where paddy fields are dominant was the least when producing crops with the same nutritional value as those grown in other hamlets. Application of unused local resources, mud and human excrement, can reduce nitrogen surplus by 49–96 kg N ha−1 per year and can provide subsidy of US$ 310–370 per year. Author Keywords: Rural ecosystem; Nitrogen flow; Nitrogen balance; Local resource