Dear Daniel
I went to the Landscape show yesterday, and got quite a bit of useful information from the Voelker stand. They have just set up a
soil exchange, which is designed specifically for the landscape sector, and will offer the following services:-
- Soils available (by soil type, quantity and source)
- Soils wanted (users can specify soil type required)
- Soil suppliers (for suppliers who have constant soil stocks available)
Although they will not be vetting each entry to the data-base, they will encourage suppliers to provide soil analysis data along the lines of this set of
parameters, in order to promote good practice in the industry.
For further details contact
Dr Andrew Butler at Voelcker Science Ltd - which incidentaly is packed with all sorts of useful information.
Oh I nearly forgot they were handing out handy plastic memory jogger cards with extracts from 'A Guide to Specifying Topsoil' Parts 1 + 2 by R.M. Voelker et al (Landscape Design March + April 1989), which gave parameters for soil attributes needed to sustain healthy plant growth :-
- Major Nutrients etc
pH 5.5 - 7.8
Electrical Conductivity < 1500 uS/cm
1:2.5 (w/v) Extract
Organic Matter > 4.0% (w/w) [1]
Nitrogen (N) > 0.2% (w/w) [2]
Extractable Phosphorous (P) > 45 (mg/kg) [3]
Extractable Potassium (K) > 240 (mg/kg) [3]
Extractable Magnesium (Mg) > 80 (mg/kg) [3]
[1] BS 1377
[2] Kjeldahl
[3] MAFF Handbook RB 427
- Phytotoxic Elements (not normally hazardous to health), based on values in ICRCL 59/83 where a pH value of 6.5 is assumed. If the pH value falls, the toxic effects and takeup of elements below will increase.
Total Copper (Cu) < 130 (mg/kg)
Total Nickel (Ni) < 70 (mg/kg)
Total Zinc (Zn) < 300 (mg/kg)
Water-soluble Boron (b) < 3 (mg/kg)
- Zootoxic Elements (which may pose hazards to health), based on trigger concentrations given in ICRCL 59/83 (open spaces etc)
Total Arsenic (As) < 40 (mg/kg)
Total Cadmium (Cd) < 15 (mg/kg)
Total Chromium (Cr) <1000 (mg/kg)
Total Lead (Pb) <2000 (mg/kg)
Total Mercury (Hg) < 20 (mg/kg)
- Stones
Maximum size 50mm
Maximum Content (2-50mm) 35% by dry weight
(the 2-5mm part
is <20% dry wt)
- Soil Texture
Sand (0.05-2mm) Max 75%, Min 20%
Sand (0.002-0.05mm) Max 60%, Min 5%
Sand (<0.002mm) Max 30%, Min 5%
Cheers
Micky