"A Modelling Approach to Global Nitrate Leaching Caused by Anthropogenic Fertilisation" 

Lin Bin-Le

National Institute of Advanced Industrial Science and Technology

Water Research,  Vol.35 No.8 pp.862-867 (2001)

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Abstract

Water quality associated with nitrate (NO3-) leaching from agricultural soils is an important environmental issue. This paper describes a new modelling approach to quantitatively evaluating the effect of the use of fertilisers on global nitrate leaching. 

A global process-based simulation model was previously developed for the nitrogen cycle in terrestrial ecosystems, in which soil inorganic nitrogen in the form of ammonium (NH4+) and NO3- was considered. After introducing data on world fertiliser consumption (FAO, 1995) into the steady-state model, the extent of disturbance to the nitrogen cycle caused by fertilisation was calculated. 

Although fertilisation resulted in an annual increase in net primary production (NPP, represented as carbon) of 18 Gt·year-1, NO3- leaching and gaseous losses of nitrogen oxides and ammonia were also accelerated. Most regions with heavy fertiliser application (over 100 kg·ha-1·year-1) showed a high annual leaching load equal to or more than 20 kg·ha-1·year-1. 

About 2.5% of the land area occupied by terrestrial ecosystems suffered a serious leaching load of more than 30 kg·ha-1·year-1. Of the total amount of applied fertilisers (138 Tg·year-1) 19% was lost to NO3- leaching, 8% to gaseous ammonia, and 3% to gaseous nitrogen oxides. The rest was assumed to be fixed in the ecosystems through vegetation uptake.

Keywords

Global biogeochemical nitrogen cycle, Ecosystem model, Nitrate leaching, Fertilisation, Leaching load