During the last 30 years, green manure/cover crops have become an important
agricultural technology for the developing world. Books on tropical soil management
written during the 1950s, 1960s or 1970s seldom mention green manures except,
perhaps, to briefly suggest they were a failure. But then in the 1980s, green manures
began making a regular appearance in the literature.1
Since the 1990s and 2000s, most
books on sustainable or ecological agriculture for the tropics (and even some books on
conventional agriculture) have included significant sections on the subject.
Despite all this recent attention to the subject, far too many people who hear the term
“green manure/cover crops” (gm/ccs) still picture fields completely covered by mucuna
(Mucuna species) or jackbeans (Canavalia ensiformis). Agronomists frequently run
experiments with three or four easily available gm/cc species, and if these species don’t
work, they conclude that gm/ccs are not appropriate for the area.