ISHS Acta Horticulturae 133: Nutrient Film Technique and Substrates, XXI IHC
SYNTHETIC TOPSOIL FROM DIGESTED SEWAGE SLUDGE |
| Author: | N. Wells |
| Abstract:
In many countries sewage sludge is applied to agricultural land to avoid dumping at sea and to utilise its nutrient value. In a small densely populated state, like the Republic of Singapore, land is not available for agriculture and dumping at sea is limited by shallow waters and national boundaries. Topsoil is no longer available in the man-modified, tropical landscape. Demand comes from: beautification of inner city areas, small scale horticulture, domestic gardens, and improvement of large-scale land reclamations. A synthetic topsoil has been formulated using a friable clay subsoil plus digested sewage sludge. Plantings on reclaimed land are now using all the available digested sludge. Placement of synthetic topsoil in poorly drained holes dug in highly compacted clay has led to root rot in certain tree species. Similar problems occur with holes made in naturally hard lateritic soils. These effects of soil compaction can be mitigated by increasing the sand content of the subsoil. | |
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