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Nitrogen levels and flows via the spreading of OWP

Total nitrogen levels in the OWP vary from 17 to 25 g/kg DM (BIO < MSW < FYM < GWS). Nitrogen is mainly present in organic form and will be available as the OWP become mineralised. Nitrogen flows per spreading range from 237 to 408 kg/ha per spreading, in the following order: MSW < FYM < BIO < GWS. The quantities of mineral nitrogen input range from 6 to 38 kg/ha.

Total nitrogen levels of OWP

The total nitrogen (tot N), ammonium nitrate (N-NH4) and nitrate (N-NO3) levels of the organic waste products (OWP) are shown in Table 1.

Table 1 . Average nitrogen levels (and standard deviations) in g/kg DM in the OWP from 1998 to 2011 (n=8)


The total nitrogen levels range from 17.3 to 24.8 g/kg DM, in the following order: BIO < MSW < FYM < GWS. Nitrogen is mainly present in organic form and will be available as the OWP become mineralised. Levels of mineral nitrogen (N-NH4 and N-NO3) are fairly low, at between 2.2 and 3.7 g/kg DW, in the following order:  BIO < FYM < MSW < GWS. Mineral nitrogen is mainly present in ammonium form, except in the case of manure, where the nitrate form may be more abundant.
The standard deviations can be significant for some OWP, reflecting the variability that can exist for the same type of OWP. This variability can be more significant for composts due to the fact that origins sometimes differ from year to year (platform changes).

Average nitrogen flow per spreading

The average nitrogen flows per spreading are shown in Table 2.

Table 2. Average flows (standard deviations) per spreading in kg/ha from 1998 to 2011 (n=8)


Total nitrogen flows range from 237.1 to 408.0 kg/ha per spreading, in the following order: MSW < FYM < BIO < GWS. The quantities of mineral nitrogen input range from 6.1 to 37.7 kg/ha. The total nitrogen quantities input are relatively high due to the OWP doses input, which are adjusted according to the soil's organic matter requirements. The nitrogen flows are above the permitted limit of 170 kg/ha in the regulation on nitrates that is applied in some regions.