Table 2.

Phosphorus (P), nitrogen (N), and potassium (K) fertilization rates, soil sampling depth, study period, and soil test phosphorus analysis at the six study sites

Sites	Country	P rate (kg ha−1)	N rate (kg ha−1)	K rate (kg ha−1)	Soil sampling depth (cm)	Study period	Soil test P
Ercé	France	0, 50	160	199	0–5	1999–2011	Olsen
Gramond	France	0, 50	160	199	0–5	1998–2011	Olsen
Les Verrières	Switzerland	0, 9, 17, 26	25	58	0–10	1992–2008	Ammonium acetate, acetic acid, EDTA
Lévis	Canada	0, 15, 30, 45	120	84	0–15	1998–2006	Mehlich-3
Maaninka	Finland	0, x (8–25)	200	50	0–20	2003–2010	Acid ammonium acetate
Siikajoki	Finland	0, x (8–25)	200	50	0–20	2003–2010	Acid ammonium acetate

x corresponds to annual local recommendations: 25 kg P ha⁻¹ in 2003 (establishment year); 10 kg P ha⁻¹ in 2004, 2005, and 2006 (established swards); 20 kg P ha⁻¹ in 2007 (second establishment year); 8 kg P ha⁻¹ in 2008, 2009, 2010, and 2011 (established swards)