Table 2.

Average dissolved P concentration upstream of the dispenser unit, (unweighted) mean reduction in dissolved P due to ferric sulfate application and (per kg dissolved P) chemical use and estimated cost of the treatment at the 15 study sites

Site	Dissolved P concentration mg L−1	Mean reduction in dissolved P conc. %	Ferric sulfate use in kg per kg dissolved P converted	Costs in EUR per kg dissolved P converted
Nautela	0.064	54	211	134a
N1	0.069	79	583	204
N2	0.062	33	243	85
N3	1.20	62	254	89
N4	0.071	78	909	318
N5	0.65	67	394	138
N6	0.020	77	953	334
N7	0.021	75	687	240
N8	1.10	79	39	14
N9	0.032	57	1241	434
N10	0.36	>95	71	25
T1	4.01	86	45	16
P1	0.061	61	417	146
P2	0.069	81	473	165
P3	0.154	79	216	76
All sites (95 % CI)		66 (61–70)	448 (248–650)	157 (87–228)b

^aAt Nautela, the ferric sulfate cost 0.46 EUR kg⁻¹ in 2011 and 0.55 EUR kg⁻¹ in 2012; at the other sites it cost 0.35 EUR kg⁻¹

^bCalculated with the 0.35 EUR kg⁻¹ ferric sulfate price