Weed management: a need for ecological approaches - Ecological Management of Agricultural Weeds - page 19

Weed management and farm profitability
An additional factor motivating the development of ecologically
based weed management strategies is the need to increase farm profitability.
In both industrialized and developing countries, the economic viability of
many farmers has been challenged as input costs rise faster than the market
values of the crops they produce. Weed management strategies that make
better use of ecological processes may improve profitability by reducing pro-
duction costs and helping farmers produce crops and livestock that are worth
more in the marketplace.
The cost-price squeeze
The cost-price squeeze confronting farmers in the USAis exemplified
by the maize-soybean cropping system used in much of Iowa, where a total of
9.3 million ha was planted with the two crops in 1998 (United States
Department of Agriculture, 1999 c ). Average yields of maize and soybean in
Iowa rose 28% and 24%, respectively, from 1972-80 to 1990-98 (Figure 1.5a).
For those same periods, average non-land production costs in constant dollars
fell 37% for maize and 31% for soybean (Figure 1.5b). Costs for maize and
soybean herbicides, in constant dollars, decreased 9% and 13%, respectively.
Increases in yields and reductions in production costs would seem to bode
well for profitability, but prices fell precipitously for both crops. Between
1972-80 and 1990-98, the average price of a metric ton of maize, in constant
dollars, decreased 60%; soybean price dropped 62% (Figure 1.5c).
Consequently, gross returns declined 47% for maize and 52% for soybean
(Figure 1.5d). Returns over non-land costs also declined sharply. For maize,
average returns in constant dollars dropped from $396 per hectare in 1972-80
to $153 per hectare in 1990-98, a 61% decline; for soybean, average returns
dropped from $530 to $182 per hectare, a 66% decline (Figure 1.5e).
For many Iowa farmers, reductions in returns per unit of cropland have
reinforced the importance of herbicides within the production process.
Herbicides accounted for 7% of non-land production costs for maize in
1972-80, but 11% in 1990-98; for soybean, the proportion of non-land costs
spent on herbicides rose from 12% to 15% (Figure 1.5f). As discussed in
Chapter 11, these increases reflect, in part, the greater land area farmers must
harvest to maintain farm-derived income, the shift toward hired applications
of agricultural chemicals to cover more hectares, and the limited time avail-
able for weed management and other farming activities when farmers add
nonfarm jobs to their existing responsibilities.
A cost-price squeeze also confronts farmers in developing countries. Beets