Sammendrag
An investigation of the wild European blueberry (E. blueberry; Vaccinium myrtillus L.) was financed for four years starting in 2008. One part of the project was to examine natural development of E.blueberry in five Norwegian fields, effect of fertilization and cutting of plants. Examinations were undertaken in two fields in Bardu municipality in Troms county and of three fields in Snåsa and Lierne municipalities in Nord-Trøndelag county. The basic idea was to examine the possibility of half cultivation on situ in the forest, a similar system as developed in north America with Vaccinium angustifolium. The five fields were arranged in block designs, and in the Bardu fields Organic Matter (OM) were added (compost and wood chips) and in the Snåsa/Lierne fields mineral fertilizers (N-P in kg haa-1: 0-0, 3-2, 3-4, 6-4). Treatments were compared with natural development. In addition to fertilization and OM the Snåsa field had two more treatments, cutting of the plants to the ground in autumn 2008 and site (placed on two moraine ridges).
From our research and investigations we can conclude that the soil O-layer is very important. The fields that performed best had thick O-layers. It could be suggested that layers close to 7 cm or thicker would be optimal. The C/N ratios indicate that N was not easily available in any field. This may explain why long shoot growth increased and more nodes were developed, when mineral fertilizer, and especially N, was added. However, number of short shoots per long shoot was not clearly influenced by fertilizer, except last year when the effect was positive- maybe a long term effect. This was not followed by higher yields throughout the years, rather the contrary, but it should be added that weather conditions the last two years were rainy; and the high yield in 2009 could have initiated alternate bearing, and more browsing because of more attractive shoots and leaves; factors that would reduce the yield in subsequent years. Adding OM had some positive influence on tiller growth in the Bardu birch-field (F1), but not in the pine-field (F2). However, annual shoot growth increased in the pine-field in the first of two years. Yields, however, were clearly reduced by adding OM in average of two years. The importance of a thick O-layer was confirmed in the examination of growth conditions on two moraine ridges. The ridge with lowest yield had less loss of ignition in the O- and B-layers, a shallower O-layer and lower levels of P, Mg and Ca in both O- and B- layers. Cutting of shoots to the ground was not beneficial and full yield potential was not recovered before the third year after cutting.
Fruit quality was influenced by latitude, soil factors and fertilization treatments. However, variations between years were the most important single factor.
Vis fullstendig beskrivelse
