Tropical Soils Research: 75 Years Backwards and 75 Years Forward.

When SSSA was created, soil science looked at soils of the tropics as something unique: red, highly weathered, acid, infertile and turned into laterite if cleared of its native vegetation. The advent of quantitative pedology, expanded soil surveys, the first world soils map, and publications openly challenging the laterite paradigm and intelligent agronomy, gradually resulted in a new paradigm that recognizes the great diversity of soils in the tropics. The term “tropical soils” is as meaningless as “temperate soils”. All 12 soil orders in the latest edition of Soil Taxonomy occur in the tropics along with 38 suborders, hundreds of great soil groups and thousands of soil families and soil series. Management systems were developed primarily in Brazil and Colombia that made Oxisols—the stereotypical tropical soil---- highly productive with soybean yields equivalent to those of Mollisols—the stereotypical temperate soil---the US Midwest. Key metrics were developed that make this breakthrough possible: The aluminum ion  as the major cause of soil acidity; amelioration of the subsoil with lime and gypsum; variable charged clays,  effective phosphorus management , effective rhizobia strains for soybeans  and Al-tolerant cultivars. About 40 years after SSSA was founded research in the tropics led the way with  placing soil biology as a science with a predictive understanding of plant litter quality; 60 years after the founding of  SSSA, the tropics led the way in using near and mid –infrared spectroscopy to rapidly characterize soil properties and 70 years after the founding of  SSSA, the first large scale use of digital soil mapping.