This chapter focuses on two main issues. First it discusses the indigenous versus modernization approaches to soil resource management in Amazonian research and development strategies. Second, the outcomes of Kayapo and conventional colonist and livestock systems are compared in terms of soil fertility and yields. The production systems of the Kayapo Indians of southern Para state are compared with those that inform current regional agricultural programs. The dramatic nature of soil degradation after forest conversion is recognized in much of the regional research on tropical agronomy. The main forms of regional agriculture that follow forest conversion are very unstable and declining soil fertility is frequently cited as a factor in agricultural failure. The most famous Amazonian example of modern soil management research is that developed by Sanchez’s group in Yurimaguas, Peru. The Yurimaguas approach has undergone several modifications over the years and increasingly incorporates practices that are less input demanding.