MINERAL NITROGEN FERTILIZERS: ENVIRONMENTAL IMPACT OF PRODUCTION AND USE - Fertilizers: Components, Uses in Agriculture and Environmental Impacts - page 29

Table 11. Average annual precipitation for the year 2011 for region

Region Average precipitation (mm per year) for 2011
Northern America 734
Central America and Caribbean 2,300
Southern America 1,442
Western and Central Europe 768
Eastern Europe 832
Africa 598
South Asia 1,025
East Asia 1,156
West Asia 213
Oceania and Pacific 1,802
Source: data.worldbank.org/indicator/AG.LND.PRCP.MM.

As reported in the IPCC 2007 report, nitrous oxide (N 2 O) is one of the major greenhouse
gases contributor with 8% to the anthropogenic global warming. Fifty to sixty percent of the
anthropogenic induced N 2 O emissions comes from agriculture and in particular from direct
soil emissions (Mosier et al., 1998). In the IPCC 2006 guidelines the updated default emission
factor for nitrogen inputs from mineral fertilizers, organic amendments and crop residues is
1%.
In several cases, the emission factor could be disaggregated based on (1) environmental
factors (climate, soil organic carbon content, soil texture, drainage and soil pH) (Table 12)
and (2) management-related factors (nitrogen application rate for fertilizer type, type of crop
and their residues, with differences between legumes, non-leguminous arable crops, and
grass) (Bouwman et al., 2002a,b; Stehfest and Bouwman, 2006). For example, crop residues
left on the fields increased the soil organic content (Spinelli et al., 2013b) and also act as
important source of N 2 O. Harrison et al. (2002) and Novoa and Tajeda (2006) have assumed
the following emission factors: 0.2% for crop residues of cereals, 2% for crop residues of
vegetables and 1% for crop residues of other arable crops. N 2 O emission also increases with
higher clay content of the soil, because the possibility of anaerobic conditions increases
(Velthof & Oenema, 1995). Lesschen et al. (2011) reported the emission factor for the type of
soil: 0.86%, 1.24% and 2.61% for sand, clay and peat soils. Furthermore, there is also
interference due to the land use as reported in Table 13.

Table 12. Annual N 2 O emissions dependent on nitrogen inputs and their relevant
environmental data in agricultural fields

Site N 2 O

emission
(kg N
ha -1 yr -1 )

N input
(kg N
ha -1
yr -1 )

Precipitation
(mm)

Temperature
(°C)

STN
(g kg -1 )

pH SOC

(g kg -1 )

Reference

Cambridgeshire,
UK

1.20 190 550 12 - 7.7 29 Dobbie &

Smith
(2003)

Nottinghamshire,
UK

2.40 165 600 12 - 5.7 11.6 Dobbie &

Smith
(2003)

Potsdam,
Germany

0.55-
3.89

150 397-569 10.1-11.3 1.4 6.3 9.0 Hellebrand

et al.