Introducing ……... Slate waste

EU Life-Environment funded project: Sustainable post-industrial land restoration and re- creation of high biodiversity natural habitats Partners: University of Wales, Bangor;Alfred McAlpine Slate; Slate Ecology Co., Pizarras- Villar del Rey Output:To produce a science-based guide to Best Practice for achieving the restoration of self-sustaining, semi-natural ecosystems of high conservation value

Scope of the project Nutrient and water delivery systems Plant responses Litter decomposition and soil formation Invertebrate, detritivore and bird biodiversity Socio-economic impacts GIS overlays of environmental variables

Soil functioning in natural and restored systems on slate waste Julie Williamson 1, Davey Jones 1, Richard Bardgett 2, Phil Hobbs 3, Ed Rowe 1, Mark Nason 1 & John Healey 1. 1 University of Wales, Bangor, 2 University of Lancaster, 3 IGER.

Rationale and Hypotheses typically, quarry sites lack topsoil H.1 theoretical C:N considerations can be used to design substrates from organic wastes for nutrient delivery nutrient cycling needs a ‘kick start’ H.2 organic matter increases nutrient cycling capacity need to develop soil biochemical indices that predict longer-term above-ground success H.3 organic amendments create a substrate biochemically comparable to that of naturally established vegetation

Method used for tree planting Slates arranged to collect rainfall 1-year old transplant Soil amendments in 3 L pocket, depth 15 cm Free-draining coarse slate waste 1m Roots moving towards fines Water-holding fines

Design of tree establishment trial 3 water-holding treatments None Boulder clay Polyacrylamide gel 3 nutrient supply treatments None*Sewage-paperNPK (15:10:10) mix slow release * mixed to a target C:N of and to deliver mineral N at the same rate as NPK in Year 1

Materials used for tree establishment Selected nutrient concentrations of the organic amendment. Target application rates to planting pocket kg.N ha -1 NPK550sewage-paper4000

Results: substrate Mineral-N content (mg N.kg -1 ) over 3 samplings (1, 7, 13 months)

Results: soil microbial biomass (mg N.kg -1 ) and basal respiration (mg C.kg -1.h -1 ) at 13 months

Results: summary of soil N pool sizes at 13 months *PMN is potentially mineralisable N

Results: comparing soil quality indices of naturally established and planted birch.

Results: Soil microbial PLFA profiles of natural and planted vegetation. Proportion (% mol) of Gram+ve bacterial PLFA to total. SSS

Results: Soil microbial PLFA profiles of natural and planted vegetation. Ratio of fungal-to-bacterial PLFA. Ratio of fungal to bacterial PLFA

Results: Soil microbial PLFA variation in natural and planted vegetation. Plot of coordinates derived from detrended correspondence analysis (Canoco)

Conclusions H.1 theoretical C:N considerations can be used to design substrates from organic wastes for nutrient delivery Yes; soil mineral N concentrations during the first 13 months in the NPK treatment were matched by the sewage-paper mix treatment H.2 organic matter increases nutrient cycling capacity Yes; as evidenced by increases in microbial biomass, respiration and potentially mineralisable N, relative to other treatments

Conclusions cont’d H.3 organic amendments create a substrate biochemically comparable to that of naturally established vegetation Sewage-paper resulted in soil microbial biomass and respiration rate comparable to those in natural systems But, microbial composition differed markedly, viz: Planted systems had: greater proportion of bacterial PLFA lower microbial C:N ratio higher respiratory quotient