Provisional values of the content of foliar potassium (g per kg dry matter) for the estimation of K-deficiency in the leaves in the period from early August to mid September (4,8,9).
| Tree species | K-Supply | |||
|---|---|---|---|---|
| Too low | Low | Normal | Optimal | |
| Acer campestre | <4 | 4-8 | 8.5-14 | > 14 |
| Acer negundo | <4 | 4-8 | 8.5-14 | > 14 |
| Acer platanoides | <7 | 7-11 | 11.5-15 | > 15 |
| Acer pseudoplatanus | <7 | 7 -11 | 11.5-15 | > 15 |
| Acer saccharinum | <4 | 4-9 | 9.5-18 | > 18 |
| Aesculus hippocastanum | < 4.5 | 4.5-8.5 | 9-14 | > 14 |
| Alnus glutinosa | <4 | 4-7.5 | 8-20 | > 20 |
| Alnus incana | <4 | 4-6 | 6.5-20 | > 20 |
| Betula pendula | <4 | 4-7 | 7.5-9 | > 9 |
| Carpinus betulus | <4 | 4-6 | 6.5-9 | > 9 |
| Corylus avellana | <5 | 5-10 | 10.5-16 | > 16 |
| Corylus colurna | <5 | 5-7 | 7.5-16 | > 16 |
| Crataegus laevigata | <4 | 4-6 | 6.5-14 | > 14 |
| Crataegus monogyna | <4 | 4-6 | 6.5-14 | > 14 |
| Fagus sylvatica | <4.5 | 4.5-7 | 7.5-15 | > 15 |
| Fraxinus excelsior | <6 | 6-10 | 10.5-15 | > 15 |
| Gleditsia triacanthos | <4 | 4-9 | 9.5-16 | > 16 |
| Juglans nigra | <5 | 5-10 | 10.5-20 | > 20 |
| Juglans regia | <5 | 5 -12.5 | 13-3 | > 23 |
| Liquidambar styraciflua | <4 | 4-6 | 6.5-18 | > 18 |
| Liriodendron tulipifera | <5 | 5-8 | 8.5-15 | > 15 |
| Malus domestica (*) | <7 | 7-12 | 12.5-16 | > 16 |
| Platanus x acerifolia | <4 | 4-6 | 6.5-17 | > 17 |
| Populus alba (*) | <4 | 4-7 | 7.5-16 | > 16 |
| Populus x canescens (*) | <4 | 4-7 | 7.5-16 | > 16 |
| P. x euramericana (*) | <5 | 5-12 | 12.5-15 | > 15 |
| Populus nigra (*) | <5 | 5-8 | 8.5-15 | > 15 |
| Populus tremula | <5 | 5-8 | 8.5-16 | > 16 |
| Prunus avium (**) | <6 | 6-10 | 10.5-17 | > 17 |
| Prunus cerasus | <6 | 6-10 | 10.5-17 | > 17 |
| Prunus domestica | <6 | 6-12 | 12.5-15 | > 15 |
| Pyrus communis (*) | < 6 | 6 -12 | 12.5-15 | > 15 |
| Quercus palustris | < 4 | 4-6 | 6.5-8 | > 8 |
| Quercus robur | <4 | 4-6 | 6.5-8 | > 8 |
| Robinia pseudoacacia | <4 | 4-7 | 7.5-20 | > 20 |
| Salix alba (*) | <6 | 6-10 | 10.5-19 | > 19 |
| Salix triandra | <7 | 7.5-10 | 10.5-19 | > 19 |
| Salix viminalis | <6 | 6.5-8 | 8.5-19 | > 19 |
| Sorbus aria | <4 | 4-6 | 6.5-14 | > 14 |
| Sorbus aucuparia | <4 | 4-6 | 6.5-14 | > 14 |
| Tilia americana | <5 | 5-10 | 10.5-19 | > 19 |
| Tilia cordata | <8 | 8-10 | 10.5-15 | > 15 |
| Tilia x euchlora | <6 | 6.5-10 | 10.5-15 | > 15 |
| Tilia platyphyllos | <6 | 6.5-10 | 10.5-15 | > 15 |
| Tilia x vulgaris | <6 | 6.5-10 | 10.5-15 | > 15 |
| Ulmus carpinifolia | <6.5 | 6.5-12 | 12.5-18 | > 18 |
| Ulmus glabra | < 6.5 | 6.5-12 | 12.5-18 | > 18 |
| Ulmus x hollandica (*) | < 6.5 | 6.5-12 | 12.5-18 | > 18 |