Abstract
Inthe region of Marabá, Amazonia, the advance of the pioneer front has lead to an intensive clearing of therainforest and to the increase of pastures that now show signs of degradation: the invasion of weedsand insect infestations. Most of the farmers perceive these problems as inevitable. However, in the lasttwenty years, the farmers have tried to successively introduce four fodder grasses that supposedly willsolve the problem. The species most recently introduced, Andropogon gayanus, was an innovation broughtby one farmer, and then progressively adopted by all of the others in Santa Maria. This type of cyclicmanagement, where cultivated plants give satisfaction in the first time and then should be replaced byothers, has quickly brought on dynamic innovations. The farmers who have prioritized pastures areconstantly seeking solutions to slow down the degradation which, in the long term, implies abandoningthe land and migrating with their families. Not surprisingly, they were the first to test and approvethe new grass species. Those who adopted the innovation with reticence are more interested by localdevelopment alternatives that aim to ensure the sustainability of the farmers’ activities (diversification,perennial cultures). The success of each innovation depends on its capacity to respond to the presentproblems, but also is contingent on the local perceptions of the degradation and sustainability process.