Articles containing the keyword 'soil density'

A simple, manually-operated and easily portable device for sampling volumetric soil cores to a depth of 100 cm with a minimum soil disturbance is described. The device consists of a sample tube, a sampler and an extension tube. A dead blow nylon mallet is used to force the sampler into the soil and a small winch attached to an aluminium tube pulls the sampler from the soil. The total weight of the equipment (sampler, mallet and winch) is 18.5 kg and may be carried in the trunk of a small car. Sampling is easily done by one person in good physical condition but four-handed operation is recommended as more efficient. The sampling device has been in heavy use during the summers of 1993–95 when several hundred soil cores have been extracted on various sites all over Finland.

• Westman, E-mail: cw@mm.unknown

The aims of the present study were to determine physical and physio-chemical properties of some Finnish forest tree nursery soils, and to examine relationships between these properties and the amount of organic matter in the soil.

The following soil tillage layer properties of 33 fields belonging to 8 forest tree nurseries were determined: soil particle size distribution, organic matter content, bulk density and density of solids, total pore space, soil water volume at potentials pF 2.0 and 4.2, available water content and air space at potential pF 2.0, active acidity, electrical conductivity index and cation exchange capacities at pH 4.5 and 8.0. The soil texture class of the tillage layer parent material was sand, only in a few cases did higher percentage of silt and clay indicate a morainic nature of parent material. The amount of organic material in the soils varied within wide limits, reflecting differences in amelioration policy between the single nurseries.

Relationships between the physical properties of the soil parent material and those related to fertility were in most cases strongly influenced by the amount of soil organic matter. Soil density values decreased as the organic matter content increased from 2 to 25%, giving rise to the increase in the total pore space. However, the amount of water held at potential pF 2.0 and the available water content did not increase with increasing organic matter content. This was due to the absence of the particle fraction in the sand. Nursery soil amelioration, involving in most cases a mixture of Sphagnum peat with sand, thus gives rise to an increase in the content of drainable water.

Cation exchange capacities were positively correlated with the organic matter content. However, the absolute number of exchange sites expressed as equivalents in the tillage layer did not increase in accordance with the increase in organic matter content due to the influence of the organic matter content upon the ratio of solids in the voids.

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• Westman, E-mail: cw@mm.unknown

• Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: lars.eliasson@norraskogsagarna.se