Five tonnes of animal life can live in one hectare of soil.

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The International Union of Soil Sciences (IUSS) is the global union of soil scientists. The objectives of the IUSS are to promote all branches of soil science, and to support all soil scientists across the world in the pursuit of their activities. This website provides information for IUSS members and those interested in soil science.

First Symposium on the Management of Tropical Sandy Soils

for Sustanaible Agriculture, Thailand

Sandy soils are the dominant soil form over significant areas of tropical Africa, South America, Australia and Asia. Due to their intrinsic chemical and physical properties these soils are marginal with respect to sustained productivity without significant and continuous inputs. Scant attention has been paid to these soils with respect to management even though these sandy agroecosystems sustain the livelihoods of millions of farmers, some of which are amongst the poorest in the world. LeInstitut de Recherche pour le Developpement (IRD, France) and the Land Development Department (LDD, Thailand) have taken the initiative to organize an international Symposium to establish the state of the art with respect to the management of tropical sandy soils and to identify research gaps with respect to a holistic approach for the sustainable development of these soils in the tropics. This symposium was held under the auspices of the International Union of Soil Science Society (IUSS) with the support of the International Management Water Institute (IWMI), the Food and Agriculture Organization of the United Nations (FAO), Khon Kaen University (KKU, Thailand) and the French ministry of Foreign affairs. Over 200 Thai participants and more than 80 foreign participants from 23 different countries representing the five continents participated in the 4 day Symposium. Altogether, 61 oral presentations and 64 posters were presented. A mid-conference field trip allowed participants the opportunity to view the sandy soils and agroecosystems of Northeast Thailand, a region were 80 % of the 20 millions inhabitants are small-farm holders.

Presentations on the physical properties of these soils highlighted the large spatial and temporal variability in properties that often are a major constraint to root development or water infiltration. A common thread in all of the presentations confirmed the large differences in soil behavior associated with minor changes in soil characteristics. This situation cannot be explained only by high heterogeneity; it seems that quality of analysis (clay and organic matter quantity and quality, detailed analysis of bulk density) could be improved and that would lead to a better understanding of processes and factors of soil changes and finally to more accurate recommendation for sustainable management. Any innovation must integrate the limited potential of the tropical sandy soils and the socio-economic situation of the farmers. The Symposium attempted to present a holistic approach to addressing the issues associated with the management of these soils that included the socio-economic dimensions in their management. It is anticipated that the proceeding of the symposium will come out as a book (published within a year) which would be the first on that subject.

There was general agreement by participants that the symposium addressed a specific gap in our knowledge and that this should become a routine undertaken in the future. The web site of the symposium ( ) will be kept alive to become a clearing house of information on tropical sandy soils. The idea of creating a working group on tropical sandy soils within the IUSS was discussed. A second symposium will probably be organized in three years, in Africa.