Weed management: a need for ecological approaches - Ecological Management of Agricultural Weeds - page 22

Table 1.2. Economic results from three comparisons of cropping systems conducted in
South Dakota

Costs other Net income over

Gross than land and costs other than

Study,location,date,management income management land and management

system,and crop rotation ($ ha 1 yr 1 ) ($ ha 1 yr 1 ) ($ ha 1 yr 1 )

Study 1: Research station plots, 1986-92
Alternative system (maize-oat alfalfa- 378 222 156

alfalfa-soybean)
Conventional system (maize-soybean- 373 252 121

wheat)

Study 2: Research station plots, 1986-92
Alternative system (wheat-oat clover- 249 156 93

clover-soybean)
Conventional system (wheat-barley- 314 218 96

soybean)

Study 3: On-farm comparison, 1985-92
Alternative system (maize-small grain 405 220 185

alfalfa-alfalfa-soybean)
Conventional system (maize-soybean) 561 304 257

Sources: Adapted from Smolik,Dobbs & Rickerl (1995) and Dobbs & Smolik (1996).

payments, was essentially the same for the conventional and alternative
systems of Study 1, but 26% higher for the conventional system than for the
alternative system of Study 2 (Table 1.2).In contrast,production costs (includ-
ing labor,but excluding land and management time) were 12% and 28% lower
in the alternative systems of Studies 1 and 2, respectively, than in the corre-
sponding conventional systems (Table 1.2).Comparisons of herbicide and cul-
tivation practices similar to those used in the conventional and alternative
systems indicated that weed control in the latter was less costly. Compared to
the conventional systems, weed control costs (including labor) in the alterna-
tive systems were 13% lower for maize,13% to 28% lower for soybean,and 89%
lower for wheat (Smolik et al ., 1993).
Largely because of lower production costs, the alternative systems of both
Studies 1 and 2 were economically competitive with the conventional systems.
In Study 1, average net income over all costs except land and management
(i.e., planning, organizing, marketing) was 29% higher for the alternative
system; in Study 2, average net income was 3% higher for the conventional
system (Table 1.2).
Different results were obtained from the on-farm comparison.The conven-
tional farm in Study 3 used a two-year maize-soybean rotation and applied