Puittaimede kasvu stimuleerimine erinevate biokütuste (puit, turvas) tuha liikidega ammendatud freesturbav ljal

Investigations made in several countries suggest that one of the most promising ways of using cutaway peatlands is their forestation. As cutaway peatlands suffer from a shortage of nutrients, one of the ways for improving growth conditions of trees to accelerate their growth would be to add peat or wood ash to the growth substrate. Use of biofuel ashes (wood and peat ash) in forestation of cutover peatlands helps balance the content of nutrients in peat substrate (shortage of P and K are considered to be growth limiting in peat soils), promotes the growth of forest cultivations, increases their tolerance to unfavourable weather conditions, diseases and pests. Thus the biodiversity of these areas will improve, the amount of greenhouse gases emitted into the atmosphere will decrease and production wastes containing nutrients (P, K etc) necessary for plant growth will be recycled. The aim of the study was to investigate the effect of fertilization on the growth of Silver birch Betula pendula Roth and Scots pine Pinus sylvestris L. seedlings on a cutaway peatland. Five treatments were established: wood ash (10 000 and 5000 kg/ha), peat and wood ash mixture (10 000 and 5000 kg/ha) and control (unfertilized field). One year old seedlings of Silver birches and Scots pines were planted. Analysis of the samples showed that the pH of peat in Ulila cutaway peatland was before treatment 3.5 and it rose after fertilization by up to 0.7 units by the end of the first growing season. The content of some mobile forms of chemical elements in the peat substrate (mg/kg) after treatments varied as follows: N 6900-15 800 (on the control plot 6100-9900), P 19.7-313.6 (on the control plot 14.8-30.6), K 85.5-4126.8 (on the control plot 52.6-128.5), Ca 1088.1-4919.8 (on the control plot 799.4-1131.8) and Mg 397.1-1730.6 (on the control plot 346.3-489.2). After the first growing season, the best results were recorded on the ash-fertilized plots. The annual height increment was 4.5 times higher in Silver birch and 1.1 times higher in Scots pine on the plot treated with 10 000 kg/ha of wood ash than on the unfertilized plot. Scots pine needles were 2.2 times longer than the needles on the control plot, which also shows a positive effect of fertilization. The root collar diameters of Silver birches in the 10 000 kg/ha wood ash application were 4.4 times larger than control and the root collar diameters of Scots pines were 2.1 times larger than control. The effect of peat and wood ash mixture was also positive compared to control, although the effect was much smaller than the effect of wood ash.