Phosphorus levels in OWPs

The total phosphorus (tot P2O5) and Olsen phosphorus (P2O5 Olsen) levels in organic waste products (OWPs) are shown in Table 1.

Table 1. Total phosphorus and Olsen phosphorus levels in g/kg DM in OWPs from 1998 to 2011 (n=8). The figures in brackets indicate the standard deviations.

The total phosphorus levels range from 7.5 to 28.3 g/kg DM, in the following order MSW, BIO < FYM < GWS. Oslen phosphorus, which evaluates the potentially available phosphorus, ranges from 0.5 to 3.3 g/kg DM, in the following order: MSW < BIO < GWS < FYM. The proportion of available phosphorus represents 6% to 26% of the total phosphorus: 6% for MSW and GWS, 9% for BIO and 26% for FYM.

Average phosphorus flows per spreading

The average total and Olsen phosphorus flows are shown in Table 2.

Table 2. Average phosphorus flows per spreading in kg/ha in OWPs from 1998 to 2011 (n=8). The figures in brackets indicate the standard deviations.

Total phosphorus flows range from 97 to 485 kg/ha per spreading, in the following order: MSW < FYM < BIO < GWS. This order is the combined result of phosphorus level in OWPs and the doses that are applied. MSW compost and BIO compost, for example, have similar total phosphorus levels, although the phosphorus flow per spreading for BIO compost is twice as high as that of RMW compost, depending on the dose applied.
When spreading compost on organic matter sparingly, GWS compost provides the most total phosphorus.
Meanwhile, FYM provides the most Olsen phosphorus and therefore the most potentially available phosphorus per spreading. Olsen phosphorus flows range from 6 to 43 kg/ha, in the following order: MSW < BIO < GWS < FYM.