Agriculture Reference
In-Depth Information
Direct and Indirect Emissions Estimation
Estimation of indirect emissions from the fertilizer production processes can be extracted
from primary data or from the database. For the Eco-invent v3 database, in addition to the
tillage, all the relevant up-stream processes involved to the mineral nitrogen fertilizers were
taken into account by considering the production technology in the respective country and the
relative import shares. Transports of the intermediate products were included as well as the
transport of the fertilizer product from the factory to the regional storehouse. Production and
waste treatment of catalysts, coating and packaging of the final fertilizer products were not
included. Transport specifications of the fertilizer product to the regional department store,
which were not included in the reference used for this inventory, were complemented by data
given in Patyk & Reinhardt (1997).
Direct field emission in air from the application of nitrogen fertilizers is calculated for
ammonia, dinitrogen oxide, nitrogen oxides and carbon dioxide as reported in Nemecek and
Schnetzer 2011: (i) to calculate the N
2
O emissions from mineral fertilizers and from crop
residues an emission factor as a percentage of nitrogen lost as N
2
O is used; (ii) to calculate
the NH
3
emissions are used different emission factor for fertilizers; (iii) the NO
x
emissions
are estimated from the emissions of N
2
O; (iiii) to calculate the CO
2
emissions is considered
the emission of 1750 g of fossil CO
2
per kg of applied urea-N (only for urea-based fertilizers).
The NH
3
emission from applied mineral fertilizers is calculated by constant emission
factors for each group of fertilizer. Instead of the emission factors suggested in Agrammon
group (2009) (15% for urea and 2% for all other mineral fertilizer) a set of emission factors
was applied that distinguishes a greater number of different fertilizer groups (Asman, 1992).
The set of emission for each group of mineral nitrogen fertilizers are reported in Table 10.
In the case of spring-summer crops cultivation, emission into water was not taken into
account because nitrates in the soil can be adsorbed by the plants and the evapotranspiration
is similar or higher than the precipitation (Spinelli et al., 2013b). In period of heavy rainfall,
in autumn and in winter precipitation accelerates uptake by the plants causing leaching of
nitrate dissolved in the water. The amount of leaching NO
3
-N is calculated by a simple
regression model (Nemecek & Schnetzer, 2011).
As reported in Table 11, in accordance with the model to calculate the leaching NO
3
-N,
the geographical variability of the average annual precipitation should be considered in order
to quantify the nitrate in ground water.
Table 10. NH
3
-emissions from mineral fertilizers (% N emitted in form of NH
3
)
Type of fertilizers Emission factor for NH
3
-N (%)
Ammonium nitrate, calcium ammonium nitrate 2
Ammonium sulphate 8
Urea 15
Multi-nutrient fertilizers (NPK-, NP-, NK-fertilizers) 4
Urea ammonium nitrate 5.7
a
Ammonia, liquid 3
a
The weighted average of ammonium nitrate (2/3 of N) and urea (1/3 of N) was taken, since no
emission factor is given by Asman (1992).
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