Weed management: the broader context - Ecological Management of Agricultural Weeds - page 505

purchase of external inputs,food prices in the USAwould increase only 9% (24

109).
In developing countries, productivity gains associated with ecological
management (see above) will often tend to decrease rather than increase food
prices. Nevertheless, farmers also need to decrease input costs and increase
production efficiency. Where labor is inexpensive relative to land and chemi-
cal inputs, intensive intercropping, multiple cropping, and agroforestry
systems can be used to increase yields per unit area, minimize soil erosion,
recycle nutrients, and suppress weeds (Beets, 1982; Steiner, 1984; Nair, 1993).
In regions where labor is expensive compared with herbicides, ecologically
based weed management strategies may be similar to those used in the devel-
oped countries. Reductions in herbicide use without corresponding increases
in labor requirements are possible through changes in tillage systems,
improved soil moisture management, better use of cover cropping and inter-
cropping practices, and development of weed-suppressive and weed-tolerant
crop varieties (Pingali & Gerpacio, 1997; see Chapters 4, 5, 6, and 7).
Throughout the developing countries,access to land,development of technol-
ogies based on local resources,and improvement in the managerial abilities of
small-scale farmers are key elements in implementing sustainable agricultu-
ral practices and maintaining an abundant, affordable food supply.

67 [2 9]

Habitat protection and wildlife conservation
Advocates of chemically intensive agriculture maintain that it pro-
tects land for wildlife habitat because farmers harvest more yield from a
smaller area (Avery, 1995). This argument presumes that low levels of chemi-
cal inputs result in low yields, and that wildlife and agriculture are inherently
incompatible. As noted earlier, studies in many countries show that low-
external-input farming systems can produce high and stable yields.
Regarding the second assumption, wildlife indeed fares poorly on industrial
farms where monoculture,high use of pesticides,and a lack of natural vegeta-
tion are the norm (Papendick, Elliot & Dahlgren, 1986). However, many
species thrive in diverse agricultural ecosystems subjected to minimal appli-
cations of pesticides.
Studies conducted in Europe and the USA have shown that bird densities
may be up to 20 times greater on organic farms than on conventionally
managed farms, an effect attributed to greater habitat diversity and addi-
tional food sources (Lampkin,1990,pp.574-9).Similarly,the diversity of wild
plant species around field edges can be higher when the use of herbicides and
other agrichemicals are minimized (Boutin & Jobin, 1998). Elimination of
herbicide and insecticide use in 3-m margins around cereal fields can increase