Human-environmental influences and interactions in shifting agriculture when farmers form expectations rationally

This paper contains a study of the response of shifting agriculture to several social and environmental changes in circumstances in which farmers form in a relatively sophisticated manner their expectations of the future values of key economic variables. Farmers are 'given' a model of expectations formation in which the expected future value of variables interact in the same manner as in the current period. With this structure of expectations, the responses of the length of fallow period (the inverse of the percentage of available land cultivated in the initial period), the total area of land under cultivation and lying fallow in the initial period of a rotational cycle, and the initial-period wage rate and spatial structure of land rent to changes in several social and environmental parameters are examined. Several salient characteristics commonly attributed to shifting, or rotational, agriculture are replicated. Higher crop prices and increased population shorten fallow periods. Those same changes also increase the total area of land under shifting agriculture. Higher interest rates also shorten fallow periods. Fallows are longer at locations farther from central markets. Less commonly recognized is that social feedbacks operate to reduce pressure on more fragile land, although this does not imply that, other things being equal, fragile tropical land will not be 'overused' in an ecological sense.