How serious a problem is soil compaction in the Netherlands? A
survey based on probability sampling
Abstract. Although soil compaction is widely recognized as a soil threat to soil resources, reliable estimates of the acreage of overcompacted soil and of the level of soil compaction parameters are not available. In the Netherlands data on soil compaction were collected at 128 locations selected by stratified random sampling. A map showing the risk of soil compaction in five classes was used for stratification. Measurements of bulk density, porosity, clay content and organic matter content were used to compute the relative bulk density and relative porosity, both expressed as a fraction of a threshold value. A soil was classified as overcompacted if either the relative bulk density exceeds 1 or the relative porosity is below 1. The sample data were used to estimate the means of the two soil compaction parameters and the areal fraction overcompacted. The estimated global means of relative bulk density and relative porosity were 0.946 and 1.090, respectively. The estimated areal fraction of the Netherlands with overcompacted soils was 45 %. The estimates per risk map unit showed two groups of map units, a `low risk ' group (unit 1 and 2, covering only 4.6 % of the total area) and a `high risk' group (unit 3, 4 and 5). The estimated areal fraction overcompacted soil was 0 % in the `low risk' unit and 47 % in the `high risk' unit. The map contains no information about where overcompacted soils occur. This was caused by the poor association of the risk map units 3, 4 and 5 with the soil compaction parameters and soil overcompaction. This can be explained by the lack of time for recuperation.