Wiltshire Archaeological & Natural History Magazine, vol. 97 (2004), pp. 95-8 
Arable Weed Survey of a Farm in South Wiltshire 
by Barbara Last 
An arable weed survey of field margins cultivated for greater biodiversity under the Countryside Stewardship Scheme 
has revealed the presence of rare plants, the seed of which had lain dormant in the ground for many years. 
In Spring 2003 a farm in South Wiltshire applied 
for and was awarded a grant under the Countryside 
Stewardship Scheme to manage cultivated field 
margins to improve biodiversity. The specific 
objective was to enable any arable plants present to 
germinate and grow outside the cropped area 
without the threat of damage by herbicides or 
competition from more aggressive species 
encouraged by the application of fertilisers. The 
margin width was set at six metres and cultivation 
took place to a depth of 15 centimetres To monitor 
the results a survey was made in July 2003 of 
selected 100 yard sections in each margin. It was 
agreed that if any margins revealed a particularly 
rich diversity of flora they would be left to re-seed 
themselves whereas others with poorer diversity 
would be grassed over. 
The soil on the farm, which may have been 
under cultivation for as long as 5000 years, is 
predominantly a light thin chalk, found especially 
on the north west fields and those at a slightly 
higher elevation. This is free draining and warm, 
with a high pH. (areas including margins 
C.D,E,EG,H,I, J and N on the attached map) unlike 
those on the remaining fields lying adjacent to the 
river Till in the south east (margins A,B,K and L) 
which are of an alluvial nature. 
An earlier botanical survey of the parish (made 
in 1999 and 2000), which included the farm, 
recorded remarkably few arable weed species. This 
was expected given the landowner’s policy of 
cultivating and spraying the fields to the margins 
producing a clean crop, occasionally interspersed 
with a grass ley. However, one notable plant found 
was Venus’s Looking-glass (Legousia hybrida) six 
plants of which turned up on the north east corner 
of Well Down 1&2 (SU 052400). 
It was anticipated in 2003 that if wild plants did 
survive in the field margins they would be likely to 
be relics of an ephemeral group evolved to 
germinate in disturbed soils arising from clearances 
in the wild wood resulting from fires and tree fall, 
or later from clearance by man, or from flash floods. 
Such circumstances give rise to short optimum 
periods with little competition from _ other 
vegetation and good light. Consequently, wild 
plants are enabled to survive by production of seed 
that has a long viability, good dispersal 
mechanisms, and which is produced in large 
quantities. Many self-pollinate, or are self- 
compatible and have a short germination to 
maturity time giving them a rapid life span in 
favourable conditions. Such plants are thus readily 
adapted to colonise clearances from the ploughing 
to which arable fields are typically subject annually 
or in rotation with grass leys. 
The Stables, Berwick St James, Salisbury SP3 4TN 
