Table 6.
Chemical composition of different potential water sources (modified after Wetzel, 2001; Sonneveld et al., 1991; Schwarz et al., 2004).
| Rainwater | Tap-, well-water | Surface water | Thresholds | |
|---|---|---|---|---|
| ECa, dS m−1 | <0.1 | 0.1–2.2 | >0.3 | 0.5 |
| pH | 4–6 | 7–8.8 | ||
| ION/ELEMENT, μmol l−1 | ||||
| Na+ | 9–50 | 50–250 | >90 | |
| Cl− | >10 | |||
| NO−3 | 30–100 | 0.1–20 | >50 | >b |
| NH+4 | 7–36 | > | ||
| K+ | 2–13 | 2.5–750 | > | |
| Ca2+ | 5–100 | 2.5–4200 | >750 | 2000 |
| Mg2+ | 2–21 | 4–2100 | >60 | 500 |
| SO2−4 | 30–100 | 3–5000 | >60 | 500 |
| HCO−3 | 0.3–100 | >450 | 10000 | |
a
EC, electrical conductivity;
b
no thresholds, typically lower than required by plants.