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Remediation of compact and degraded surface soil layers within natural habitats - BD1307(1)

The presence of compacted and degraded material in surface layers of clay and peat soils inhibits the full potential of many wetland ESA and CS schemes, as well as being unfavourable for plant communities and bird habitats. In this study, available literature, experimental results and practical field experience in soil water management on both peat and mineral soils will be reviewed with a view to developing recommendations for remediation of compact and degraded surface soil layers. Exploratory studies will also be performed and will take the form of laboratory investigations on undisturbed soil samples taken from damaged field situations, in order to examine their potential to assist in identifying practical field techniques for rewetting such degraded surfaces.

The information review will be composed of 7 specific objectives which are outlined as follows, together with ways in which they might be achieved: 1. Assessment of wetting characteristics of peat and mineral soils which have been subjected to excessive drying and compaction; 2. Identification of critical factors controlling potential rate and degree of rewetting that may be achieved; 3. Determination of flooding tolerances of wet grassland plant species and communities to ensure no serious damage occurs to communities during rewetting; 4. Possible ranking of plant species in terms of their potential abilities to re-structure and stabilise damaged soils following rewetting; 5. Identification of the most appropriate sub irrigation, surface flooding or fissuring techniques for rewetting in particular field situations; 6. Highlighting of effective soil fissuring techniques; and 7. Provision of improved recommendations for fissuring and rewetting techniques. The exploratory studies will investigate effects of both initial soil unit density and rewetting moisture tension on soil rewetting rates and final densities in clay soils; such studies will also assess the feasibility for using initial soil density, exchangeable cations and degree of structural degradation as criteria on mineral soils for identifying wetting requirements and overall potential for soil improvement. Peat samples exhibiting differing degrees of denaturation will also be subjected to rewetting tests under different moisture tensions and will be evaluated for swelling characteristics, together with changes in the physical condition of the peat soils that might affect their water holding capacity and water transmission properties. Furthermore, undamaged peat samples will be exposed to different degrees of drying followed by rewetting to pinpoint potential threshold drying rates and limits beyond which structural recovery may prove difficult.
Project Documents
• FRP - Final Report : Remediation of compact and degraded surface soil layers within natural habitats   (298k)
Time-Scale and Cost
From: 1999

To: 2000

Cost: £20,789
Contractor / Funded Organisations
University - Silsoe College
Fields of Study
Environmental Stewardship