Knowledge, science, and practice in ecological weed management: farmer–extensionist–scientist interactions - Ecological Management of Agricultural Weeds - page 102

The rapid change in agriculture and weed control methods in Great Britain
from the 17th to 19th century illustrates the central role played by farmers in
the development of farming methods (Elliot et al ., 1977; Pretty, 1991, 1995,
pp. 181-3). These centuries were characterized by increasing private tenancy
of rural lands, urbanization, population growth, and industrialization.These
factors influenced agricultural practices. During this period key technologies
with weed control implications contributed to the intensification of crop pro-
duction. Farmers developed crop rotations that included legumes like red
clover and alternated cereals with “cleaning”crops such as turnip, potato, and
forage beet. Cleaning crops planted in wide rows could be cultivated more
easily during the crop cycle than the traditional small-grain cereals such as
wheat and barley, which were categorized as “fouling” crops. Iron and steel
parts for plows, harrows, and cultivators increased both the degree and preci-
sion of soil disturbance.In the 18th century,cultivation with horses improved
labor efficiency in weed control. Improved seed cleaning equipment virtually
eliminated Agrostemma githago and Lolium temulentum , weeds that had been
extremely difficult to remove from small grains with prior methods (Elliot et
al ., 1977). During this period new weeds continued to be introduced, as they
had been in previous centuries. Weeds introduced in this period included
Cardaria draba , Veronica persica ,and Galinsoga parviflora (Godwin,1960).Floristic
composition also shifted in response to both changing weed control practices
and other crop production factors. The effect of soil fertility on weed floristic
composition, for example, was clearly shown in experiments at Rothamsted,
England, started in 1843. In low fertility plots, species like Equisetum arvensis
and Aphanes arvensis were found, whereas at intermediate and high fertility
Ranunculus arvensis and Stellaria media were more frequent (Cousens &
Mortimer, 1995, pp. 181-2). This suggests that the increasing use of animal
manure, lime, ashes, bone meal, and green manure, as well as field drainage,
also contributed to changing weed complexes.
The initial ideas for all these innovations originated with farmers and in
local workshops (Pretty, 1991). Neighboring farmers and farmers from other
regions observed the ideas in practice or learned of them through farmer
clubs, books, and newspapers, all of which became increasingly common
during the period. The number of books on agriculture, written primarily by
farmers, increased from 2-10 in the last half of the 16th century to 150-400
by the beginning of the 19th century. Other farmers adapted the new ideas
and reported their experiences and experiments at fairs, in printed material,
and at farmer club meetings.
In the later half of the 19th century in the British Isles, Europe, and the
USA, a new sector emerged in the development of agricultural knowledge. In