Critical accumulation of fertilizer-derived uranium in Icelandic grassland Andosol

Environmental Sciences Europe

Table 1 Soil properties, fertilizer annually applied, sampling depth at Sámstaðir and Geitasandur long-term experimental sites

Treatment ID	Fertilizer annually applied (kg ha⁻¹)			Soil depth	Total C	Total N	Bulk density
Treatment ID	N	P	K	(cm)	% DM	% DM	g cm⁻³
Sámstaðir (1950–2004)		Histic Andosol
0P (a)	70	0	75	0–5	15.9	1.19	0.34
0P (a)	70	0	75	5–10	9.7	0.8	0.45
39P (e)	70	39.3	75	0–5	14.6	1.11	0.34
39P (e)	70	39.3	75	5–10	8.8	0.74	0.45
Geitasandur (1958–2007)		Vitric Andosol
0P (a1)	120	0	80	0–5	9.5	0.62	0.49
0P (a1)	120	0	80	5–10	2.2	0.17	1
39P (d1)	120	39.3	80	0–5	16.7	0.98	0.27
39P (d1)	120	39.3	80	5–10	2.5	0.18	0.94
80P (a2)	120	78.9^a (55.7)	80	0–5	22.5	1.22	0.2
80P (a2)	120	78.9^a (55.7)	80	5–10	3.5	0.23	0.84
80P (d2)	120	78.9^b (67.5)	80	0–5	22.1	1.16	0.23
80P (d2)	120	78.9^b (67.5)	80	5–10	3	0.2	0.89

^a0 kg ha⁻¹ year⁻¹ was applied from 1958–1972; 79.6 kg ha⁻¹ year⁻¹ was applied from 1973–2007. 55.7 kg ha⁻¹ year⁻¹ was the average P application rate in 1958-2007
^b39.3 kg ha⁻¹ year⁻¹ was applied from 1958–1972; 79.6 kg ha⁻¹ year⁻¹ was applied from 1973–2007. 67.5 kg ha⁻¹ year⁻¹ was the average P application rate in 1958–2007