Monday 9 January 2012

Allotments No 18.3 Contamination No 3 - Obnoxious Weeds

Many allotmenteers spend time clearing their newly acquired plot of weeds, namely:
  • the "rooties" - the perennials - bindweed, brambles, couch grass, nettles and the like;
  • the "big seedies" - the perennials - thistle, dandilion, and the like;
  • the "little seedies" - the annuals - chickweed and the like.
After the first clearance the process is repeated until all the weeds are eliminated. That is the theory! I have read that there are buried in gardens and allotments seven years of weed abundance. In fact seeds, etc may exist underground for centuries and reappear upon the turning of soil after that time...? 

Although a nuisance, the above mentioned weeds are relatively innocuous: beware of the "obnoxious weeds". They are a class of weeds which come under statutory controls. This post touches upon some of the obnoxious weeds and the reasons for the special controls pertaining to them. 

Hogweed: An invasive river bank loving weed which blots out other vegetation.

Japanese Knotweed:  A Victorian introduction as an elegant architectural plant, the Japanese knotweed escaped from gardens and now invests the many odd places it has reached,  eg railway embankments.

Ragwort:  A countryside weed which gets onto allotments, this plant can be fatal to horses if it is cut, dried  and taken into the hay stock!

Although the buddleja and contoneaster are probably not statutory weeds and are not invading allotments, the link shows the importance of preventing invasiveness and the need to control it when it exists!
http://www.bbc.co.uk/news/uk-england-dorset-16475562

Tuesday 3 January 2012

Allotments No 18 - Contamination of Land No 2

A serious case of contamination of allotment land came my way this week. It is so serious that an allotment site in Newport (Gwent) is to close permanently. Remedial works could make the land useable but would cost upto £195,000. The report indicated that growing of fruit trees and vegetables might not be possible, even after remediation.

The causes of contamination of gardens and allotments are various. If there is any reason to suspect pollution it is essential to investigate by:
  • a desk study; and,
  • an on-site investigation.
Pointers to possible contamination include:
  • the physical remains of industrial and other buildings and machinery;
  • waste and oil spills from former industrial workings;
  • contaminates from the burning of painted timber, tyres and other materials;
  • residues from polluted flood waters;
  • long-term air-borne contaminates; and,
  • spills from off-site events, eg a fire or explosion, which result in pollution "pathways" to the garden or allotment site. 
It is possible that a plot-holder may contaminate the patches of ground by such practices as:
  • the inadvertent overuse of fertilisers or chemical for pest / weed controls; 
  • the regular bonfire burning of plastics, painted timber, tyres and other materials containing toxic substances; and,
  • burying asbestos sheeting and other potentially harmful materials.