Water extractable phosphate in composts and land-applied organic materials
Link to this table.

Feedstock Biosolids treatment Total solids(%) pH P2O5 (% dry wt) P (% dry wt) WEPa(% of Total P)
Leaf / yard wastes NA 39.4 7.7 0.34 0.15 8.4
Leaf / yard wastes / food NA 47.5 7.4 0.42 0.18 7.4
NA 53.9 7.4 0.43 0.19 6.8
Biosolids / wood chips2 No P removal 39.8 7.2 0.78 0.34 20.5
An. digest /No P removal 59.2 7.2 1.87 0.82 7.7
No P removal 48.1 6.7 1.6 0.7 22.3
Chemical P removal 38.8 5.5 3.65 1.59 1.8
Biosolids / wood chips / yard wastes2 No P removal 72.1 6.6 0.81 0.35 12.2
Biosolids / yard wastes / WTRb2 No P removal 53.5 8.3 1.67 0.73 4.6
No P removal 47.8 7.9 1.68 0.73 4.1
Leaf / yard wastes / gelatin residuals NA 51.1 8.3 2.19 0.96 2.0
Biosolids / wood shavings2 Biological P removal 42.8 5.7 2.41 1.05 13.3

aWEP = Water extractable phosphorus, bWTR = water treatment residuals (Source: Phosphorus and Compost Use Dynamics, Alexander, 2016)
2Minnesota does not compost biosolids per rule. Only source separated organic matter and yard waste are allowed in compost.