Benefits of recycled phosphorus

A series of 14C glucose addition trials demonstrated how struvite additions affected microbiology activity in a different way to conventional phosphate fertilisers.

Cumulative CO2 emission was similar to control tubes illustrating slower C utilisation and turnover. Benefits from addition of mycorrhizae was also demonstrated (data not shown) indicating no effect from use of struvite with mycorrhizal associations.

Figure 1. Cumulative CO2 emission from rootzones following phosphate fertiliser addition. Error bars show SE of mean.

Root chamber trials for Lolium perenne in a sand based rootzone with different combinations of MAP (mono-ammonium phosphate) and pearl struvite at a rate of 60kg/ha P clearly illustrated significantly (P<0.05) better rooting where higher proportions of pearl are utilised
(100% pearl, 80:20 Pearl:MAP, 60:40 pearl:MAP).

The greatest rootmass was measured for 80:20 combination.

Figure 2. Root biomass (g/pot) for struvite pearl and MAP combinations. Error bars show SE from mean. Letters signify comparative significant difference (P<0.05)

A second series of root chamber trials again with seeded Lolium perenne illustrated the importance of depth of incorporation of any seeding fertiliser.

Significantly greater rootmass (P<0.05) was measured when fertilizers were incorporated at 60mm compared with 30mm and surface application.

Results were significant for all P fertiliser types measured (data not shown).

Figure 3. Root biomass (g/chamber) measured at different fertiliser placement depths. Error bars show SE from mean. Letters signify comparative significant difference (P<0.05)