Status of cadmium, lead, cobalt and selenium in soils and plants of thirty countries [antikvár]

Preface This volume is the result of a great deal of effort by many people in many countries — an international example of cooperation. It had its inception in the early 1970s, when preparatory work was underway for a review of trace elements in soils and agriculture, a review that was later published as FAO Soils Bulletin 11. In preparing the material for that publication it became painfully obvious that despite all the hundreds of papers that had been published on trace elements, there was no comparabilifl. The multitude of methods used for sampling and laboratory analyses led to an equal multitude of results. There was no single base standard against which they could be compared. When this fact was brought by the author to the attention of FAO and the Government of Finland it led to a cooperative project between them, TF/INT/129/FIN, 'Trace Element Study'. That^projeeLJiartedjn 1974, and involved scientists in thirty countries collecting samples from more than 3 600 soil and plant samplmg sites, according to strict protocols on sampling and handling, followed by analyses by one laboratory using the same analytical procedures for all samples. For this important task the facilities of the Institute of Soil Science, Agricultural Research Centre, Finland, were used. That first project studied six micronutrients (B, Cu, Fe, Mn, Mo and Zn) and five macronutrients (N, P, K, Ca and Mg), and was the first to be carried out on a global scale where each nutrient or soil characteristic from all samples was determined using the same method, thus guaranteeing strict comparability. In order to obtain ba^ground information essential for interpreting the nutrient data, the study also included determinations of a number of important soil characteristics (pH, texture, organic matter content, cation exchange capacity, electrical;^y^ conductivity and CaCOj-equivalent) from more than 3 600 soil and plant sampling sites. The work was reported by the undersigned in 1982 as FAO Soils Bulletin 48^ Although the results of the first project gave a good overall picture of the micronutrient status in the countries involved and indicated areas where micronutrient problems of deficiency or toxicity could be expected, they did not provide quantitative data on the effects on yields of different crops. Hence the object of the second project, GCP/INT/379/FIN, 'Micronutrient Assessments at the Country Level', was to quantify the effects of various micronutrients on yields, and, especially, on those of economically important food and cash crops. Further, as stated in the Project Document, "the purpose of the project is to familiarize the governments of the participating countries with their natural soil micro- (and macro-) nutrient status, to draw the attention of agricultural authorities to existing problems, to assist in developing national micronutrient investigation programmes by building up national expertise in diagnosing and curing micronutrient disorders, to find more information on the critical deficiency and toxicity limits, and to give quantitative guidelines for solving the problems at a practical level." That project was implemented in 14 developin^countries and in Finland, the donor country. It was based on field trials from~which both plants and soils were analysed. The results, reported as FAO Soils Bulletin 63, showed thatsome degree of zinc deficiency, acute nr latent p.xistgd in 49%_Qf.the trial sites, and similarlyfor boron molybdenum (15^). copper (14%). manganese (10%) and iron (3%). Toxicities of these micronutrients were rare.