Ash spreading on peatlands

Regular Recycling of Wood Ash to Prevent Waste Production – RECASH

A Life Environment Demonstration ProjectLIFE03 ENV/S/000598

Contents• Lack of nutrients on peatlands• Deficiency symptoms• Nutrient deficiency on different bogs• Needle sampling• Peat sampling• Effects of ash spreading on peatland• Comparison of nutrient amounts in PK fertilizer and ash• Effects of wood ash spreading on forest growth• Peatland forests and drained peatlands in Finland• Preconditions for ash spreading

Lack of nutrients on peatlands• On nutrient-rich peatlands there is usually enough nitrogen (N).• There may occur deficiency of phosphorus (P), potassium (K),

boron (B) or other mineral nutrients.• Nutrient deficiency causes colour symptoms and growth

disorders:• yellow-tipped needles or premature shedding of needles (P)• chlorosis of needles (K) • multi-leadered bushy crowns (B)• resistancy decreases

• Forest growth is weak in spite of good draining.• Symptoms are easiest to identify on small trees.

Deficiency ofphosphorus (P) on

pine

Deficiency ofpotassium (K) on

pine Photos: Metla, MTT 688

Deficiency ofboron (B) on pine

Deficiency symptoms (1)

Deficiency symptoms (2)

Deficiency ofnitrogen (N) on pine

Photo: Metla, MTT 688

Deficiency of many nutrients

Photo: Kemira 2002

Nutrient deficiency on different bogsNutrient

content class N P K B

S. fuscum miresCottongrassDwarf-shrubV-vitis idaeaSmall-sedgeV. myrtillusTall sedge

Herb-rich

Eutrophic

Needle sampling• The need of fertilization on peatland

forests can be defined by needle analysis.• The needles are collected during

the dormancy of the tree.• A sample contains 1-2 shoots from

the south side of the top of 5-10 trees, choosing the biggest and healthiest trees, not growing by a ditch.

• The samples with their site information are analyzed.

the shoots are sent for the

analysisPicture: Viljavuuspalvelu 1991

south

Peat sampling

a sample from the depth of 5-15 cm

Picture: Viljavuuspalvelu 1991

• Manual squeezing test (von Post scale):• Colourless water squeezed

from peat indicates nitrogen-poor soil.

• A more detailed definition of the nutritional status can be done by soil analysis:• A sample is taken from a peat

layer in the depth of 5-15 cm.• The final sample of 0,5 litre to

be analyzed is combined of several smaller samples.

Effects of ash spreading on peatland

• There is no nitrogen (N) in ash, but phosphorus (P), potassium (K) and micronutrients in a balanced combination for trees.

• Fertilization effect begins slowly but is long-termed (20-50 years).

• Wood ash is alkaline; lower acidity stimulates micro-organism activity, increases the nitrogen intake of trees and decreases the toxic character of other elements.

• No phosphorus (P) leaching.• Cadmium does not increase in fungi and berries.• Ash spreading increases undervegetation and breeds the small

game stock population.

Comparison of nutrient amounts in PK fertilizer and ash

Source: Forestry Centre of Central Finland

Portion P K Mg Mn S B Cu Cd kg / ha

PK fertilizer 500 45 80 0 0 7 1,5 1,0 0

Wood ash 7 000 50 100 35 3570

0,8 0,8 45

Peat ash 4 000 55 10 5 5 15 1,6 0,3 6

The amounts of nutrients in peat ash are highly dependant on the peat used in ash production.

Effects of wood ash spreading on forest growth

• According to Finnish Forest Research Institute the addition to the volume increment reached by ash spreading is 2-4 m3 /ha/year

Photos: Forestry Centre of Central Finland

Ash fertilization in 2001 in Central Finland. Photo in August 2004. The age of the forest is about 100 years. A nutrient-poor mire.

Dwarf shrub pine bog. Ash fertilization in 2001. Photo in 2004: Forestry Centre of Central Finland.

Dwarf shrub pine bog. Ash fertilization in 2001. Photo in 2004: Forestry Centre of Central Finland.

Peatland forests and drained peatlands in Finland

Proportion of peatlands of forest land Proportion of drained areas of peatlands

Preconditions for ash spreading• Ash spreading, for example 7 tonnes / ha, in Finland costs appr. 210 €/ha + VAT.

• Following conditions are required for the state-supported (40-55 % of the costs) ash spreading in Finland:• Needle analysis

nutrient imbalanceadequate fertility; no need for nitrogen (N)

• No need for silvicultural measures• Well drained wetlands• Young development stages of peatland forest• An accepted plan for repairing fertilization