Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970–2030
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- Bouwman, A.F., Van Drecht, G. & van der Hoek, K.W. Sci. China Ser. C.-Life Sci. (2005) 48(Suppl 2): 767. doi:10.1007/BF03187117
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Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970–2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N2O and NO emissions, and nitrate leaching from the root zone. Global NH3-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg·yr−1 between 1970 and 1995, and will further increase to 44 Tg·yr−1 in 2030. Similar developments are seen for N2O-N (2.0 Tg·yr−1 in 1970, 2.7 Tg·yr−1 in 1995 and 3.5 Tg·yr−1 in 2030) and NO-N emissions (1.1 Tg·yr−1 in 1970,1.5 Tg·yr−1 in 1995 and 2.0 Tg·yr−1 in 2030).