Micronutrients [antikvár]

iii FOREWORD In spite of favourable developments in the use of fertilizers to increase crop production, two to six times more of the micronutrients are still being removed annually from the soil than are applied to it together with other nutrients in mineral fertilizers or separately. Some of the nutrients removed are replaced by those in straw, farmyard manure, etc. but on the average the nutrient balance is likely to remain negative. This applies especially to less developed parts of the world. Micronutrients have not been applied regularly to soil in conjunction with common fertilizers, and fertilizing soils with micronutrients only is likely to promote imbalances between.these nutrient groups as well as between individual nutrients. Furthermore, increased yields through intensive cropping and use of high yielding varieties, losses of micronutrients through leaching, liming, a decreasing proportion of farmyard manure compared with chemical fertilizers, the increasing purity of chemical fertilizers and several other factors are contributing towards accelerated exhaustion of the supply of available micronutrients in soils. It is apparent that hidden micronutrient deficiencies are far more widespread than is generally estimated. Micronutrient problems, which today may be considered only local, may well become more serious in the relatively near future, occurring extensively over new areas and creating widespread and complicated production restrictions if they are not properly studied and diagnosed in time. Even though much of the nature of micronutrient functions is known, the application of this knowledge is not easy. Recognizing the complexity of the problem, FAO in collaboration with the Ministry of Agriculture, Government of India and with the financial support of a trust fund project GCP/RAS/064/N0R of the Government of' Norway organized a national seminar 'bn the efficiency and application of micronutrients in-agriculture" during September 1979 in New Delhi, India, with the objective of collating and discussing the mass of research results generated in this field. One of the recommendations of this seminar was to bring out a handy publication geared to the needs of-transferring the technology to the benefit of the farmers. This Bulletin has therefore been prepared in simple language in order to help field staff in the correct diagnosis of micronutrient deficiencies and how to amend them. "The information provided cannot be site-specific and is therefore intended to provide basic knowledge and guidance in a wide range of circumstances. Suggestions for possible improvements and additions for a future version of the Bulletin will be most welcome.