Micronutrients in South and South East Asia, edited by Peter Andersen, Junoo K. Tuladhar, Krishna B. Karki, and Surya L. Maskey. Kathmandu, Nepal: ICIMOD, 2005. xxii + 239 pp. Free download at http://books.icimod.org. Hardcopy: US$20 (developed countries), US$15 (developing countries), US$10 (ICIMOD member countries). ISBN 92-9115-210-2.
This publication is the outcome of an international workshop held in September 2004 in Kathmandu. The 3 excellent keynote presentations made by Professors R.S. Gibson, R.M. Welch, and K.B. Karki et al form the highlights of the volume. They are complemented by 23 research and review papers by invited scientists, largely from South Asia, addressing a wide range of micronutrient constraints related to sustainable crop production and human nutrition, as well as means and methods to alleviate these problems. I am particularly delighted to note that this publication advocates a paradigm shift in the field of micronutrient research from management for crop production to unfolding the role of micronutrients in human nutrition. Considering the emerging complicity of suboptimal micronutrient contents in raw and processed food items, discussions on the role of micronutrients in human nutrition are very refreshing and timely. I sincerely congratulate the organizers, editors, and scientists for their meaningful and useful contributions.
Gibson clearly shows that the potential impact of iron and zinc deficiencies on human health is far more severe than that of protein malnutrition, which is commonly believed to be more harmful. While changes in cooking and modifications in local diets could help to significantly improve food micronutrient value, dietary interventions such as supplementation, food fortification and bioenrichment remain necessary to alleviate deficiencies in diverse socioeconomic groups.
The paper by Welch depicts a dramatic decline in micronutrient intake over the years in the diets of the average population in developing nations in general, and in South Asia in particular. This state of affairs is a matter of serious concern. Welch's in-depth analysis vividly demonstrates that the productivity of pulses has been continuously declining due to widespread suboptimal availability of boron, zinc, and molybdenum in soils. These deficiencies, in turn, seriously impair the intake of iron and zinc by people living on rice-and-pulse-based diets. Welch recommends addressing these problems by adding micronutrients from external sources, selecting and breeding micronutrient-efficient cultivars, using genetically modified plants, and diversifying cropping systems. His suggestion of integrating conventional breeding with biotechnology to develop micronutrient-efficient cultivars is of topical relevance and of great practical utility for marginalized small-scale farmers, and thus for the majority of farmers in South and South East Asia.
Karki and his colleagues present a well-structured inventory of micronutrients across the ecological regions of Nepal. They specifically emphasize the need to include boron and molybdenum in the fertilizer schedule, especially for vegetables and in areas supporting high-intensity cropping. According to the findings, Nepalese soils generally have sufficient manganese and iron contents. However, soil categorization in the study is based exclusively on soil test data and is therefore often misleading—particularly with respect to iron. In order to strengthen soil-test-plant response correlation, it is necessary to include in the regression equations the role of key soil properties that influence iron availability from soils. Alternatively, the need for iron treatment may be corroborated by the active iron content of the plants. It is not clear why boron and molybdenum are included in the list of DTPA extractable micronutrients (Table 3; p 26). In Table 4 (p 26), the critical limit of boron is given as 2 ppm in soils—a value that appears unusually high if hot water was used as an extractant. Although the extractant is not mentioned in the study, boron availability across a wide range of soils and crop growing environments is normally assessed by hot water extraction.
The 3 papers from Session 1 focus on various human diseases and disorders related to trace element deficiencies. The authors present some promising results of zinc supplementation preventing childhood pneumonia and diarrhea, which are the 2 most common causes of death among children in developing countries. Results regarding the promotion of orange-flesh sweet potato in eastern India to combat vitamin A deficiency are highly useful from a practical standpoint. Another case study on selenium supplementation for goats shows that this leads to increased fertility rates, shorter birth intervals and reduced kid mortality. These findings, too, are of great socioeconomic value, given that the livelihoods of many non-farm holders depend on the survival and productivity of small ruminants such as goats.
The 3 papers from Session 2 deal with the delineation of micronutrient status in the cultivated soils of Nepal and Haryana, India. Findings show that the worst deficiency in these soils is that of zinc, followed by boron. The authors recommend taking immediate steps to alleviate these deficiencies. This is indispensable for the sustainable development of agriculture, and important with a view to minimizing adverse health effects on rural communities and their livestock support systems which primarily depend on agricultural produce for their dietary needs. I would recommend generating more crop response data to validate the delineation of micronutrient deficiencies based upon soil test values alone.
The 8 papers from Session 3 cover various facets of the scientific, socioeconomic and political aspects of soil nutrient management. The paper by P. Andersen provides a new orientation for agricultural extension systems, advocating an appropriate blending of scientific and farmers' indigenous knowledge for the effective transfer of technologies. This section is informative and rather comprehensive, containing many experiential and experimental findings. However, some typological mistakes have crept into the text: eg, Mega-gram (Mg) is written as mg (pp 79–85).
The 6 papers from the last session address issues related to micronutrient management vis-à-vis crop productivity and produce quality. There are some very promising results on micronutrient treatment to alleviate deficiencies. Supplementation through seed enrichment by soaking in a micronutrient solution seems to be an economically favorable option for resource-poor farmers. However, in order to make seed-soaking a general recommendation, further verification under diverse crop growing environments is needed.
On the whole, all papers are of topical relevance and practical utility. The invited papers by authorities in their own fields, who present results from across the globe, constitute the heart and soul of the publication. The contributions from Nepal are unique in the sense that these provide information on the status of micronutrient research in a country where research until recently was in its infancy. Findings on micronutrients in soils and crops from India, Pakistan and Bangladesh could usefully be extrapolated for tackling micronutrient problems in Nepal. The incorporation of “South East” in the title of the book is somewhat intriguing, as the papers pertain principally to South Asia. Overall, these proceedings are a very useful compilation with nearly flawless editing. The subject matter and simple language are the book's innate strengths. I recommend it not only to agricultural scientists engaged in micronutrient research, but also to teachers, social scientists, farmers and other stakeholders.