Marja-Liisa Juntunen

Fertilization practice in Finnish forest nurseries from the standpoint of environmental impact

In 1996 a questionnaire concerning actualsystems and practices used in production ofseedlings was sent to 33 Finnish forestnurseries. A total of 28 nurseries answered thequestionnaire. These replies represented about80% of the total production of forestseedlings in Finland. The nurseries used about200 metric tons of fertilizers in 1996, whichwas about 25% of the fertilizer use in 1976.Explanations for the decrease in fertilizationare the shift from bareroot production tocontainer production and the decrease in totalproduction from 190 to 150 million seedlings.Finnish nurseries applied about 100 mg N and50 mg P per container seedling shipped, and820 mg N and 240 mg P per bareroot seedling.The mean annual applications of N and P in 1996were about 180 kg/ha and 90 kg/ha for containerstock and 130 kg N/ha and 40 kg P/ha forbareroot stock. However, the variation betweennurseries was large.

Nitrogen and phosphorus leaching and uptake by container birch seedlings (Betula pendula roth) grown in three different fertilizations

Leaching of nitrogen (N) and phosphorus (P) through container peatmedium and N and P uptake by seedlings were determined in commercial productionof birch grown with three different types of fertilization. Half of the amountof nutrients was premixed into the peat medium and the other half was appliedasliquid (=fertigated) in the treatment (PF) commonly used in Finland. In twoother treatments all nutrients, either totally (P-VN) or partly (P-N) inslow-release form, were premixed into the peat. Independently of the treatment,the largest proportion (60 to 80%) of total N leached during May and June.During two growing seasons, the amounts of N leached from PF treatments (9 to36kg ha−1) were as large as the amounts of Nleachedfrom P-VN and P-N treatments (24 to 46 kg ha−1).Due to fertigations between container trays, however, the total N load perhectare was greatest in the PF treatments. In the soil water 0.5meter beneaththe container area, the N concentration varied from 10 to 60 mgl−1. The morphological and chemical properties of theseedlings did not differ greatly between treatments.

Growing Picea abies container seedlings in peat and composted forest-nursery waste mixtures for forest regeneration

Abstract The suitability of using composted forest-nursery waste as a component in growing medium was studied. Norway spruce [Picea abies (L.) Karst.] seedlings were grown in containers filled with sphagnum peat (100P), forest-nursery waste compost (100C) and in peat mixtures containing 25 or 50% compost by volume (75P25C and 50P50C, respectively). Morphological and chemical characteristics of the seedlings and the water and nutrient contents of the growing media were studied during 22 weeks of nursery cultivation. The seedlings were outplanted the following spring, and the survival and growth were followed for 3 years. Compost additions decreased seedling height, diameter and shoot dry mass, but root dry mass was the same in 100P and 75P25C after nursery cultivation. Foliar nutrient concentrations were optimal in all the seedlings, although foliar nitrogen content was lower the greater the proportion of compost in the medium. Compost additions did not affect the root-egress potential tested before outplanting. The 100P seedlings grew significantly more than the other seedlings during the first summer at the forest site. Thereafter, compost additions did not affect growth, but the final height and diameter were still the lowest in 100C. The results suggest that forest-nursery waste compost has potential to be used as a component of peat-based growing medium. However, specially adjusted nursery-cultivation practices need to be used for compost-containing media.

Survival of uninucleate Rhizoctonia species during composting of forest nursery waste

Forest nursery waste was composted with and without different nitrogen sources in 300 litre composts. Uninucleate Rhizoctonia (teleomorph Ceratobasidium bicorne) was selected as a model pathogen for testing the survival of pathogens during composting. Hyphal culture of the pathogen was mixed with waste material and buried in nylon mesh bags in the composts. Temperature, water content, pH and volume reduction were monitored during the composting period. Carbon, nitrogen and phosphorus concentrations were determined in the initial compost materials. After composting, the pathogen was baited with Norway spruce seedlings, and damping-off due to uninucleate Rhizoctonia was recorded. None of the seedlings showed any symptoms of damping-off in the treatment in which forest nursery waste was composted with cutter-chip bedded horse manure, indicating eradication of the pathogen. The survival of the test pathogen in the other treatments is a risk for the future use of the composted material in forest nurseries.

Leaching of propiconazole and chlorothalonil during production of Pinus sylvestris seedlings in containers

The risk of environmental contamination by pesticides is not well known in container production of forest seedlings. Leaching of propiconazole (Tilt 250 EC®) and chlorothalonil (Bravo 500®) from peat container medium into the ground was monitored during three growing seasons in nursery production of Scots pine (Pinus sylvestris L.) seedlings. Fungicides were applied at about 20 day intervals from the end of July until November. The annual load of leached propiconazole (25–183 g active ingredients ha‐1) was greater than that of chlorothalonil (5 to 82 g active ingredients ha‐1). The proportion of leached to applied propiconazole was large, 4–29%, but less than 1% of the applied chlorothalonil was detected in leachates. The downstream percolation of water in the soil beneath the container area was small. After extra irrigation into the ground, the detected concentrations of chlorothalonil in soil water 0.5 m beneath the ground surface were 0.4–2.4 μg 1‐1.