Crop diversification for weed management - Ecological Management of Agricultural Weeds - page 364

regions, including soybean/wheat (Reinbott et al ., 1987), fava bean/wheat
(Bulson, Snaydon & Stopes, 1997), alfalfa/oat (Hesterman et al ., 1992), and red
clover/maize (Scott et al .,1987).Alack of appropriate machinery for managing
other intercrops may represent insufficient attention from agricultural engi-
neers, not an inherent incompatibility of intercropping with mechanization
(Cordero & McCollum, 1979; Vandermeer, 1989, pp. 199-201). Intercropping
is most common on small, tropical farms with little access to improved
farming technologies, but it is not restricted to such situations. For example,
better animal-drawn weed control implements are being designed for use in
intercropping systems (Anderson, 1981). Can appropriate technologies be
developed for alley cropping systems to prevent competition from weed-
suppressing trees against herbaceous crops, perhaps by root pruning? More
attention from engineers will allow the potential of diversified cropping
systems to be expressed more fully throughout the world.
A fourth challenge is social: systems for propagating farmer knowledge
about diversified cropping systems are needed.In both temperate and tropical
regions, farmers managing complex cropping systems often have site-specific
knowledge about their impacts on weeds (Exner, Thompson & Thompson,
1996; Thurston, 1997). To better disperse farmer-generated knowledge,
policy makers,educational institutions,and funding agencies need to support
networks linking farmers, extension educators, and researchers.
A fifth challenge is political: obtaining the benefits of cropping system
diversity on a large scale requires that national and regional policies promote
crop diversity. If greater reliance on nonchemical weed management is
deemed environmentally desirable, then government policies must be consis-
tent with this goal. Government programs to stabilize farm income must
promote longer crop rotations.Private and public lenders must be encouraged
to recognize the value of crop diversification in stabilizing yields and in reduc-
ing challenges from weeds and other pests. In many cases, local and regional
markets need to be developed for diversified products.The political work nec-
essary to accomplish these and other related tasks is enormous, but so are the
potential benefits to farmers and the environment.
REFERENCES
Abraham, C.T., & Singh, S.P.(1984).Weed management in sorghum-legume
intercropping systems. Journal of Agricultural Science (Cambridge) ,103, 103-15.
Agboola,A.A., & Fayemi,A.A.(1972).Fixation and excretion of nitrogen by tropical
legumes. Agronomy Journal ,64, 409-12.
Aguilar,A.,Aguilar,V., Somarriba, S., & Staver, C.(1997).Selective weed management for
soil conservation in young coffee: evaluation of herbicide-mechanical and