Nutrition of Sitka spruce on peat-problems and speculations.

  • D.A. Dickson
Keywords: Soil, afforestation, class, nutrient.


This paper deals with the problems of the mineral nutrition of Sitka spruce (Picea sitchensis Bong. Carr.) on peatland soils in Northern Ireland and speculates on the solutions to some of them. There are nutritional problems on the mineral soils in the country (Savil and Dickson, 1975) but on certain peat soils they are more acute and occur at an earlier stage than on any other major soil type. However not all peats are unproductive and it must be emphasised that there is as big a difference in potential productivity for Sitka spruce on low altitude valley or fen peat and upland blanket peat as there is between agricultural production on the best arable and poorest grazing soils in the country. By far the most important group of peat soils devoted to forestry in Northern Ireland are the blanket peats; there are only relatively small areas of raised bog or fen peat and even less afforestation on them. About 80 % of the blanket peat is over 1 m deep and this type of peat has been classified into four "nutrient classes" ranging from the nutrient rich eutrophic class to the very impoverished dystrophic type. The classes are recognised by the characteristics of the natural vegetation. It is not claimed that the scheme is perfect; nor is it suggested that it necessarily has relevance outside a forestry context but it has the merits of simplicity and usefulness in practice. There are very few nutritional problems with Sitka spruce on eutrophic peat. Only small areas of dystrophic peat have been planted in the past and this type is no longer planted with spruce. Deficiency of potassium (K) is the main nutritional problem on mesotrophic semi-flushed peat, but this is fairly easily identified and overcome. Also it has been suggested (O'Carroll et al. 1973) that K deficiency may become less acute as the trees increase in size. The biggest problems both in extent and severity occur on oligotrophic peat (unflushed blanket bog) (Dickson and Savill, 1974) and the remainder of this paper deals with this topic.
How to Cite
Dickson, D. (1977). Nutrition of Sitka spruce on peat-problems and speculations. Irish Forestry. Retrieved from
Conference Papers