ABSTRACT
Agricultural intensification worldwide is characterized by a high input of fertilizers, pesticides, and open nutrients and energy balances. There are indications that the highly productive fertilizers and seed technologies introduced over the past several decades may be reaching a point of diminishing returns (Burgos, 1995). Prospects for expanding low-cost irrigation-one of the driving forces behind yield increases-are also becoming more limited, as are the prospects for converting marginal lands into productive arable land (Moore et al., 1989). Furthermore, new technologies such as genetically engineered yield-increasing plants are not expected to be major factors in food production, especially in developing countries during the next few decades.
