Nature and Properties of Red Soils of the World

Red soils are highly leached soils of the humid tropics having a high content of sesquioxides. In the current system of U. S. Soil Taxonomy, red soils are usually designated under the orders of Oxisols, Ultisols, and occasionally Alfisols, Mollisols and even Inceptisols. Red soils are predominantly found in South America, Central Africa, South and Southeast Asia, China, India, Japan and Australia. In general, these soils have good physical conditions for plant growth although they often have very low water-holding capacity. Low natural fertility is the main limiting factor for good crop production on these soils and they are frequently acidic and deficient in all essential nutrients, especially N, P, K, Ca, Mg, S, Zn, B, and Cu. Adequate applications of lime and fertilizers are important strategies for replenishing soil fertility and improving crop yields on these soils. In addition, cultural practices such as appropriate crop rotation, improvement of organic matter content, use of nutrient efficient or acid tolerant plant species or cultivars, and control of soil erosion can optimize nutrient use efficiency and improve crop yields on these soils. In China, utilization of red soils for crop production by farmers depends not only upon the employment of such practices but also upon socio-economic factors and the availability of adequate incentives.