Weed management: the broader context - Ecological Management of Agricultural Weeds - page 498

a review of the compound's acute and chronic toxicity and declared it an
“imminent hazard” to agricultural workers and the environment (Haskell,
1991). At the time dinoseb was prohibited in the mid 1980s, 3 to 5 million kg
of the material were applied annually to a variety of American crops (Gorney,
1987).
The Nordic countries have pursued cost internalization through taxes on
pesticides. These are intended to reduce pesticide use and encourage farmers
to develop alternative strategies. Finnish and Norwegian farmers pay 2.5%
and 11% taxes, respectively, on pesticides; Swedish farmers pay a 20% “regula-
tion charge”on top of price, a 10% “environmental tax”on price, and a charge
equivalent to $5.65 per hectare per pesticide application (Pearce & Tinch,
1998).As discussed later in this chapter,imposition of such taxes,initiation of
educational programs, and greater reliance on newer low-rate products led to
a 54% reduction in herbicide use (on a kg ha 1 basis) in Sweden during the
1980s (Bellinder, Gummesson & Karlsson, 1994).
In principle, a program for internalizing the external costs of pesticide use
could tax more harmful materials at a higher rate. However, reducing the
multidimensional impacts of any particular pesticide to a single number may
be impossible using purely objective procedures (Dushoff,Caldwell & Mohler,
1994).A general tax on pesticides aims to internalize some unknown fraction
of the costs of chemically based agriculture as a way to encourage an alterna-
tive approach. In contrast, a tax that varies with the specific pesticide aims to
shift use from more harmful to less harmful materials. In principle, specific
taxes may be fairer. However, a general tax on pesticides may better internal-
ize costs to ecosystems and communities that result from interaction of pesti-
cide use with other aspects of farm management like farm size and degree of
specialization. A general tax is also probably more effective for changing the
overall direction of a nation's agriculture.
Some ecological weed management measures can also have external costs if
used improperly. In particular, tillage and cultivation for weed control can
lead to soil erosion with consequent damage to long-term farm productivity
and aquatic ecosystems. However, erosion is not an inevitable consequence of
tillage. Many methods are available to minimize erosion, including rotation
with sod crops, terracing, strip cropping, sod water ways, cover crops,
mulches, wind breaks, and use of conservation tillage equipment (Brady,
1984, pp. 534-69). Insufficient use of these practices results more from eco-
nomic conditions that force farmers to maximize short-term profits in order
to remain solvent than from ecological weed management. Careful use of soil
conservation practices allows low-purchased-input and organic farms to