Artikkelit jotka sisältää sanan 'phosphorus'

Phosphorus and potassium deficiencies are common in Scots pine stands growing on drained peatlands. In this study, the foliar nutrient concentrations and stand growth were monitored after the application of phosphorus and potassium fertilisers of different solubility in four experiments on thick-peated drained peatlands in northern central Finland. The studied stands involved three fertilisation treatments: (i) unfertilised control, (ii) rock phosphate and potassium chloride, and (iii) apatite and biotite. The growth of stands was monitored 20–25 years after the fertilisation. Needles were sampled four times: 4–9, 11–14, 16–19 and 21–24 years after the fertilisation. According to foliar analyses, the trees on the control plots suffered from severe phosphorus and potassium deficiencies. Rock phosphate and apatite fertilisation increased the foliar phosphorus concentrations above the deficiency limit, and the effect was still noticeable 21–24 years after the application. Both potassium sources, that is, the slowly soluble biotite and the water-soluble potassium chloride increased the foliar potassium concentration to an adequate level. Potassium chloride increased the concentrations faster and stronger than biotite during the first years (4–9) after the applications. The situation was reversed when 11–14 years or more had passed from the fertilisation: the biotite fertilised stands had higher potassium concentrations. The fertilisation treatments decreased the foliar nitrogen, zinc, manganese, copper and boron concentrations. The fertiliser applications increased the stand volume growth considerably. Raw phosphate and potassium chloride increased the volume growth significantly already during the first five-year period. The effect of the apatite and biotite treatment was weaker during the first 10 years, but became stronger with time. During the period 19–24 years after the fertilisation, the stand growth on the biotite plots was equal to that of the plots fertilised with potassium chloride. However, during the whole study period the differences between the treatments remained insignificant. The results showed that slowly soluble apatite and biotite are suitable sources of phosphorus and potassium for pines on drained peatlands. However, to avoid boron deficiency, also boron should be added simultaneously.

• Moilanen, Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie 7, FIN-91500 Muhos, Finland Sähköposti: ei.tietoa@nn.oo
• Pietiläinen, Sähköposti: ei.tietoa@nn.oo
• Issakainen, Sähköposti: ei.tietoa@nn.oo

We studied the natural regeneration of a cut-over peat bog in the Sumava Mountains, Czech Republic. The spontaneous revegetation by vascular plants has been limited by extreme abiotic conditions left after peat mining. Only 1-2% of the total area was recolonized by Sphagnum mosses. This was mainly because drainage channels are still drying out the bog. Only plants tolerant to water stress such as Juncus effusus, Molinia caerulea, Eriophorum angustifolium and E. vaginatum were able to establish there. A key species colonizing bare surface is a clonal plant E. angustifolium. It forms circular polycormons of densely aggregated ramets. As in other radially spreading phalanx plants, the oldest (central) part of the system gradually dies, previously connected ramets become separated, and ring polycormon becomes open to recolonization by other plant species. We analyzed the relationships between species richness of the ring and their size, percentage litter cover, distance to seed sources, and soil fertility. The number of plant species was higher in the middle of the polycormons. The soil was more fertile in the central area than in the surroundings. We conclude that the restoration of highly disturbed habitats can be facilitated by clonal behavior of pioneer populations.

• Lanta, Faculty of Bilogical Sciences, University of South bohemia, Branisovska 31, CZ-370 05 Ceske Budejovice, CzechRebuplic Sähköposti: ei.tietoa@nn.oo
• Doležal, Sähköposti: ei.tietoa@nn.oo
• Samata, Sähköposti: ei.tietoa@nn.oo

The nutritional status of Scots pine (Pinus sylvestris L.) stands growing on a nitrogen-rich, drained pine mire in western Finland was studied after refertilization using needle analysis and the response of stand volume growth. The main aim was to find out if K-refertilization alone could maintain or increase the volume growth without causing a nutrient imbalance between K and P. The initial fertilization was carried out in 1961 - 62 using PK fertilizer and refertilized in 1976 and 1989 with different combinations of nitrogen (N), phosphorus (P), potassium (K) and boron (B). Needle samples were taken and the tree stands were measured in 1996 and 2001. Peat samples were taken in 2002. According to the needle analysis results, the concentration of P was above the deficiency level in all the treatments in 1995 and 2000. There was a clear shortage of K in the needles collected from the control treatment, but the concentration of K was still adequate 12 years after the latest K refertilization. The volume growth of the stands clearly responded to the 1976 refertilization with K alone, which was probably due to the fact that trees had been suffering from K deficiency before the first refertilization and 14-15 years thereafter. After the second refertilization, the combination of K and P increased the annual volume growth more than refertilization with K alone. This indicates that about 25 years after the initial fertilization, there was already some shortage of P. The highest stand volume was associated with the combined K (1976) and PK (1989) refertilization treatment. Refertilization with N did not increase stand volumes during the study period.

• Rautjärvi, The Finnish Forest Research Institute, Joensuu Research Centre, Box 68, FIN-80101 Joensuu Sähköposti: ei.tietoa@nn.oo
• Kaunisto, Sähköposti: ei.tietoa@nn.oo
• Tolonen, Sähköposti: ei.tietoa@nn.oo

The state of the environment is currently evaluated by indicators of air and water quality. Sustainable land use requires an assessement of soil quality. Soil quality indicators should relate soil processes to management practices. The supply of N and P contributes to crop productivity, but can degrade air and water quality. In this paper, we will present organic soil N and P attributes that can make up soil functions. Nitrate was the only detected mineral N form in organic soil materials with pH (0.01M CaCl2 ) exceeding 4.4. Lowest C/N ratio of cultivated sapric soil materials was 15, showing high nitrate-supplying capability. Total P concentration was between 760 and 1960 mg P kg–1 both in organic and inorganic forms when pH (0.01M CaCl2 ) increased above 4.7, the recommended minimum pH value for cultivated organic soils. Lowest C/P ratio as organic forms was 340 for sapric materials containing less than 22% ash, indicating organic P sequestration capability (C/P > 300). However, the low N/P ratio of 23 (i.e. 340/15) also indicated capability for organic P availability to plants. Since N and P are related to organic matter transformations, the C/N/P/S multiratios of selected organic matter fractions, analyzed as compositional data (computation procedure presented), need further consideration as integrated N and P attributes in combination with pH and climatic indexes, in order to adapt N and P diagnosis and recommendation models to specific organic soil agroecological zones.

• Parent, Centre de Recherche en Géomatique, Laval University, Ste-Foy (Quebec), Canada G1K 7P4 Sähköposti: ei.tietoa@nn.oo
• Viau, Sähköposti: ei.tietoa@nn.oo
• Anctil, Sähköposti: ei.tietoa@nn.oo

The nutrient concentrations of the water percolating through fertilised peat cores were investigated in a greenhouse experiment. The nutrient concentrations in the peat cores were also determined before and after the experiment. The fertiliser treatments were 500 kg ha-1 of PK peatland fertiliser, 5 000 and 25 000 kg ha-1 of birch ash, and an unfertilised control. The cores were watered on three occasions after application of the fertilisers. The percolation water collected from the fertilised cores contained significantly more nutrients than the control. The total amounts of leached nutrients were equivalent to 0.01 - 20.1 % of the nutrients in the peat cores, K clearly being leached the most. The susceptibility of the nutrients to leaching followed the order K > Mg > Ca > Mn > P. The fertiliser treatments also increased the leaching of nitrate and ammonium. The amount of leached nutrients was relatively the highest from the PK treatment, but in absolute terms the highest from the largest dose of wood ash. According to the peat analyses, the concentrations of most of the nutrients had increased only in the surface layer of the peat (0 - 5 cm). In contrast, the K concentrations had increased throughout the whole profile (0 - 20 cm). The application of large amounts of ash fertiliser should be avoided in order to minimise nutrient leaching losses. Although the fertilisers used in this experiment have been or are being replaced by new types of fertiliser, the results of this study can be used to facilitate the interpretation of the results of field experiments in which these fertilisers have been used..

• Silfverberg, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland Sähköposti: ei.tietoa@nn.oo

The effects of fertilization and refertilization on the growth of pubescent birch (Betula pubescens) stands growing on drained peatlands in northern Finland were studied in eight field experiments. The treatments were: (i) control with no fertilization, (ii) fertilization with nitrogen (N), (iii) fertilization with phosphorus and potassium (PK), and (iv) fertilization with nitrogen, phosphorus, and potassium (NPK). The sites represented four different mesotrophic to eutrophic site types with stand median heights ranging from 7 m to 13 m. Tree growth was monitored at stand level during periods of five to eleven years following the setting up of the experiments and during periods of 4 to 7 years following the repetition of the treatments in 1985. At the end of the second period, sun-exposed leaves were sampled from two stands in August 1990 for the purpose of conducting foliar nutrient analyses. The first-time fertilization treatments did not affect tree growth on any of the site types. Following the repetition of the treatments, the stands responded positively to NPK or PK fertilization on all site types except on the shallow-peated herb-rich peatland forest. There was no response to mere N-fertilization on any of the site types. The growth responses observed were weaker than those reported for Scots pine in similar climatic conditions. Key words: Betula pubescens, foliar nutrients, growth responses, nitrogen, peatland, phosphorus, potassium

• Penttilä, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland Sähköposti: ei.tietoa@nn.oo
• Moilanen, Sähköposti: ei.tietoa@nn.oo

Abstract: The stand-level responses to fertilization and refertilization were studied in seven factorial field experiments established in 1974-1976. The factors were nitrogen fertilization (N) and phosphorus-potassium fertilization (PK). The factorial treatments were applied at two levels: (i) control and (ii) fertilized with a dosage following the currently used Finnish forest fertilization guide-lines. The spruce-dominated stands were selected from areas drained according to normal forestry practises between 1932 and 1969. The sites covered fairly well the trophic variation that occurs on spruce-dominated peatlands in the mid-boreal zone in Finland. Tree growth was monitored during two periods of five to seven years. The second period followed the refertilization in 1985. At the end of the second period, one-year-old sun-exposed needles were sampled from the four southernmost stands for nutrient analyses. The effects of fertilization on tree growth were generally fairly weak and insignificant, especially during the first study period. After refertilization, the effect of N was positive in three stands on mesotrophic sites. The foliar nutrient analyses of unfertilized spruces showed low concentrations of N, P and Cu. PK-fertilization increased foliar P concentrations and, in some cases, also K concentrations. Since the PK-fertilizer included some borate, it also increased foliar B concentrations. N-fertilization did not affect foliar N, P or K concentrations but it decreased foliar concentrations of Ca, Zn, and B in some cases. Both the growth responses and the foliar nutrient analyses indicated that nitrogen was the most deficient macro-nutrient. Key words: foliar nutrients, growth responses, mires, nitrogen, phosphorus, Picea abies, potassium

• Moilanen, The Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie, FIN-91500 Muhos, Finland Sähköposti: ei.tietoa@nn.oo
• Penttilä, Sähköposti: ei.tietoa@nn.oo
• Issakainen, Sähköposti: ei.tietoa@nn.oo

Runoff from 16 artificial minibasins was sampled after fertilizer application before snowmelt in March and after it in May. Extremely high concentrations of phosphorus, potassium and ammonium were observed during the snowmelt period in April. Key words: fertilization, leaching, peatland, phosphorus

• Ahti, Finnish Forest Research Institute, Department of Peatland Forestry, P.O. Box 18,01301 Vantaa, Finland Sähköposti: ei.tietoa@nn.oo
• Paarlahti, Sähköposti: ei.tietoa@nn.oo

This study included growth and needle analysis in ash-fertilized spruce and pine stands near Oulu (65 °N, 26 °E). Most of these stands, totalling 770 measured trees, were on peat and fertilized in wintertime 1980 and 1981 as practical work with 40 m3/ha. By 1985 there was a clear increment of growth, especially in spruce stands, probably due to the great amount of phosphorus (375 kg/ha) applied. Keywords: peatland forestry, tree growth, ash-fertilization, phosphorus.

• Silfverberg, Department of Peatland Forestry, The Finnish Forest Research Institu­te, Unioninkatu 40 A, 00170 Helsinki, Finland Sähköposti: ei.tietoa@nn.oo
• Issakainen, Sähköposti: ei.tietoa@nn.oo

The short-term effects of wood ash, PK and NPK fertilizers on total N and P contents of various mosses at an old drainage area in eastern Finland are studied. Total N contents increased after NPK treatment and total P contents increased after treatments that contained phosphorus (NPK, PK, wood ash). N contents of some mosses also increased after treatments which did not contain any nitrogen (PK and wood ash). On these plots drainage and obviously the fertilizer treatment fastened the decomposition rate of the peat and at the same time the mobilization of the nutrients. On the control plots (no fertilization) the N contents of the mosses did not differ statistically between the years in either of the study sites. The P contents of some mosses decreased on the control plots of the spruce swamp. One reason for this was apparently the level of the ground water, which did not lower so much in the spruce swamp than in the pine mire, and so the mobilization of the nutrients remained smaller. The observed nutrient contents of the peat mosses were much smaller than those of the forest mosses and the nutrient contents were also smaller at pine mire than at spruce swamp. Keywords: bryophytes, fertilization, drained peatlands, nitrogen, phosphorus.

• Jäppinen, University of Joensuu. Department of Biology. P.O. Box 111, SF-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo