C.M.A Taylor, P.M. Tabbush
On moorland and heathland soils in Great Britain nitrogen deficiency can severely restrict the growth of certain conifer species, including Sitka spruce, the main commercial species. Until the 1970s this was thought to be due solely to competition from heather and was commonly known as 'heather check’. However, increased planting of Sitka spruce on very nutrient-poor soils revealed that, even after removal of heather by herbicide treatment, growth was still limited by low availability of nitrogen. This can be caused by limited soil nitrogen capital and/or slow rate of nitrogen mineralisation. Application of nitrogen fertiliser can overcome this deficiency although several applications may be required to achieve full canopy closure. Once this stage is reached demand for nutrients is reduced due to shading of competing vegetation, improved nutrient cycling and capture of atmospheric nutrients and further inputs of nitrogen should not be required. The major difficulty facing forest managers in determining the treatment of a nitrogen deficient stand is deciding whether heather control, application of nitrogen fertiliser, or a combination of both, will yield the most cost-effective response on any given site. This Bulletin explains the background to the problem, categorises the range of site types involved, and advises on the treatment available. This Bulletin is still available in hardcopy.
190 x 250mm | 36 pages | colour photographs