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Download Full PDF - 28.09 MB - The Society of Irish Foresters

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<strong>The</strong> Response <strong>of</strong> Sitka Spruce toSulphate <strong>of</strong> Ammonia and GroundRock Phosphate on PeatE. P. Farrell and D. M. McAleese lABSTRACTMajor site amelioration is needed to overcome the serious physicaland nutritional problems encountered by tree crops on blanket bog.A 4 X 3 N P factorial experiment was established at Glenamoy in1967 to examine the response <strong>of</strong> P'62 Sitka spruce to fertilizers onpeat. <strong>The</strong> trees had received 85 g ground rock phosphate (G.N.A.P.)per plant at planting. G.N.A.P. was applied at levels <strong>of</strong> 0, 375, 750and 1,500 kg/ha and sulphate <strong>of</strong> ammonia (S/A) at 0, 625 and1,250 kg/ha. <strong>The</strong> fertilizers were applied in 1967. <strong>The</strong> 625 kg/ha S/Aapplication was repeated in 1969. Height growth results from thefirst four years <strong>of</strong> the experiment and foliar analysis from the firstthree years are presented here.<strong>The</strong> results confirm the need for a second application <strong>of</strong> phosphateon oligotrophic peat. Significant height growth responses wereobtained, but no additional response was observed above the lowestlevel <strong>of</strong> G.N.A.P. application. A significant height growth responseto S/A was also recorded. Serious leader breakage, which occurredin 1969, was found to be related to total tree height. Foliar Nconcentrations were significantly increased by both fertilizers. <strong>The</strong>results indicate that tree growth will be seriously limited below1.0 % N. Concentrations <strong>of</strong> P were significantly reduced by S/ Aapplication. This was a dilution effect due to an increase in needleweight. Both fertilizers significantly reduced foliar K concentrations.INTRODUCTION<strong>The</strong> afforestation <strong>of</strong> blanket bog in the West <strong>of</strong>lreland with Sitkaspruce (Picea sitchensis (Bong.) Carr.) and contorta pine (Pinuscontorta Doug!.) represents a movement away from an ecologicalapproach to species selection. No species in general use in Ireland isadapted to the low fertility and poor physical conditions <strong>of</strong> blanketbog. <strong>The</strong> physical properties <strong>of</strong> the peat make the necessary drainage1 Department <strong>of</strong> Agricultural Chemistry and Soil Science, University College,Dublin.

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