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  • Zinc in SoilS and crop nutrition Brian J. Alloway

    International Zinc Association

  • Zinc in SoilS and crop nutrition B. J. Alloway

    Second edition, published by IZA and IFA Brussels, Belgium and Paris, France, 2008

    International Zinc Association 168, Avenue de Tervueren, Box 4

    B-1150 Brussels, Belgium Tel: + 32 2 776 00 70 Fax + 32 2 776 00 89

    (www.zincworld.org)

    International Fertilizer Industry Association. 28 rue Marbeuf

    75008 Paris, France Tel: + 33 1 53 93 05 00

    Fax: + 33 1 53 93 05 45/ 47 (www.fertilizer.org)

    Layout and graphics: Hilaire Pletinckx

    The designation employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the International Zinc Association and the International Fertilizer Industry Association. This includes matters relating to the legal status of any country, territory, city or area or its authorities, or concerning the delimitation of its frontiers or boundaries.

    Mention of any proprietary products in this report does not necessarily imply that their use is endorsed by either the author or the publishers.

  • 1 FOREWORD

    1

    Zinc (Zn) is an essential micronutrient and has particular physiological functions in all living systems, such as the maintenance of structural and functional integrity of biological membranes and facilitation of protein synthesis and gene expression. Among all metals, Zn is needed by the largest number of proteins. Zinc-binding proteins make up nearly 10 % of the proteomes in eukaryotic cells, and 36% of the eukaryotic Zn-proteins are involved in gene expression (Andreini et al., 2006, J. Proteome Res. 5: 3173-3178). Tolerance to environmental stress conditions has a high requirement for Zn to regulate and maintain the expression of genes needed to protect cells from the detrimental effects of stress (Cakmak, 2000, New Phytol. 146:185-205).

    Zinc deficiency appears to be the most widespread and frequent micronutrient deficiency problem in crop and pasture plants worldwide, resulting in severe losses in yield and nutritional quality. This is particularly the case in areas of cereal production. It is estimated that nearly half the soils on which cereals are grown have levels of available Zn low enough to cause Zn deficiency. Since cereal grains have inherently low Zn concentrations, growing them on these potentially Zn-deficient soils further decreases grain Zn concentration. It is, therefore, not surprising that the well-documented Zn deficien- cy problem in humans occurs predominantly in the countries/regions such as India, China, Pakistan and Turkey where soils are low in available Zn, and cereals are the major source of calorie intake.

    Zinc deficiency in humans is a critical nutritional and health problem in the world. It affects, on average, one-third of the world’s population, ranging from 4 to 73 % in different countries (Hotz and Brown, 2004, Food Nutr Bull 25: 94-204). The recent analyses made under the Copenhagen Consensus in 2008 (www.copenhagenconsensus.com) identified Zn deficiency, together with vitamin A deficiency, as the top priority global issue, and concluded that elimination of the Zn deficiency problem will result in immediate high impacts and high returns for humanity in the developing world.

    It is, therefore, highly important to develop cost-effective and quick solutions to the Zn deficiency problem. Low Zn in plant tissues is a reflection of both genetic- and soil-related factors. A basic knowledge of the dynamics of Zn in soils, understanding of the uptake and transport of Zn in plant systems and characterizing the response of plants to Zn deficiency are essential steps in achieving sustainable solutions to the problem of Zn deficiency in plants and humans.

    This book “Zinc in Soils and Crop Nutrition” by Brian Alloway contributes significantly to our better understanding of the complexities of Zn dynamics in soil and plant systems. It contains very valuable basic and practical information for a wide audience, including students, agronomists and scientists who are involved in research, extension or education in soil science, plant mineral nutrition, plant physiology and also human nutrition. Detailed information on the prevalence and diagnosis of Zn deficiency problems for a number of countries and crop plants is an excellent feature of this book.

    This book has been available electronically since 2004. It has now been decided to publish this updated version in a print format. This is a great idea that will further contribute to a wide distribution of the useful information contained in the book.

    I would like to congratulate Prof Brian Alloway on this excellent achievement, and thank the International Zinc Association (IZA) and the International Fertilizer Industry Association (IFA) for their support which has made the publication of such a valuable book possible.

    Ismail Cakmak Sabanci University July 2008, Istanbul

  • ABBREVIATIONS AND GlOSSARy

    2

    AAS atomic absorption spectrophotometry (analytical method for trace elements)

    AB-DTPA ammonium bicarbonate with DTPA, soil test reagent

    Acrisols red-yellow coloured soils typical of humid tropical, sub-tropical and warm temperate areas, often found associated with Ferralsols (FAO-UNESCO Soil Classification).

    Adsorption retention of ions on the surface of the soil solid phase

    Aerobic rice rice grown without continuous flooding under aerobic soil conditions (also called upland rice)

    Aerosols particles < 30 µm in diameter suspended in air

    Alfisols moist mineral soils with medium to high base status which contain a horizon of clay accumulation. Occur in cool-hot humid areas and also semi-arid areas

    AM arbuscular mycorrhizae (fungi which colonise the root and assist in the absorption of soil ions from the soil solution) - also called vesicular arbuscular mycorrhizae (VAM) Anion negatively charged ion (e.g. hydroxyl ion OH- )

    Arenosols sandy textured soils (sand particles 0.05-2 mm in diameter) whose properties are dominated by the high sand content (e.g. low clay contents and low available water capacities)

    ASNS alternate submerged, non-submerged rice growing system (an alternative to continuously flooded paddy rice (see also GCRPS)

    Auxin compound regulating plant growth (e.g. IAA-indole acetic acid)

    Biofortification process of increasing the content (‘density’) of micronutrients, such as zinc, in food crops, especially cereals. There are two types: agronomic biofortification involves using fertilisers to increase the density of zinc in cereal grains; genetic biofortification uses specially-bred crops which have been selected on the basis of their ability to concentrate zinc and other micronutrients in their edible parts, such as grains.

    Biosolids another name for sewage sludge – the insoluble residue from waste water treatment

    Bread wheat used for baking bread (in contrast to durum wheat)

    C3 plants plants with a basic photosynthesis mechanism which fixes carbon dioxide in only one stage

    C4 plants plants which fix carbon dioxide in two stages and can raise its concentration in their leaves above ambient levels

    Ca calcium

    CaCO3 calcium carbonate

    Calcisols soils in which there is a substantial accumulation of calcium carbonate (calcareous soils), characterized by a ‘calcic’ horizon (>15% CaCO3 equivalent)

    Calcite calcium carbonate (CaCO3)

    Cation positively charged ion (e.g. zinc occurs as divalent cation Zn2+)

    Cation Exchange the sum of exchangeable cations that can be adsorbed by a soil, soil constituent or other material at a Capacity (CEC) particular pH

    Cd cadmium

    CGIAR Consultative Group on International Agricultural Research (co-sponsored by FAO, International Bank for Reconstruction and Development (World Bank), the UN Development Programme and the UN Environment Programme)

  • Chlorophyll green pigment in plants involved in photosynthesis

    Chlorosis lack of chlorophyll formation resulting in yellow stripes and patches on leaves (major symptom of zinc deficiency)

    CIMMYT International Maize and Wheat Improvement Centre

    Clay minerals aluminium silicate minerals with a large surface area, clay particles < 2 µm in diameter. Clay minerals give soils part of their adsorptive capacity, cohesiveness and water retention

    Co cobalt

    Co-precipitation occlusion of metal ions in precipitates of iron, manganese and aluminium oxides

    CSIRO Commonwealth Scientific and Industrial Research Organisation (Australia)

    Cultivar (cv) cultivated variety of a plant species with distinctive characters (often vary considerably in zinc efficiency/tolerance to deficiency)

    Cu copper

    Cut soils soils in which the topsoil has been removed during levelling of fields for irrigation

    DAP diammonium phosphate (high analysis phosphatic fertiliser, 21% N 23% P) usually with very low contents of metal impurities

    dS m-1 deciSiemens per metre (measure of electrical conductivity [EC] in the soil solution – used in the assessment of salinity in soils)

    Diagenesis the process by which sediments derived from the weathering of rocks are converted into sedimentary rocks and may eventually undergo weathering and form the parent material of sandy soils (Arenosols etc)

    DTPA diethyl triamine penta-acetic acid, soil test reagent

    Durum wheat used for making pastas an