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Fluid Journal : Summer 2017
11 The Fluid Journal Summer 2017 ▼ DOWNLOAD of water uptake. Micronutrients promote the strong steady growth of crops that produce higher yields and increase harvest quality--maximizing a plant’s genetic potential. In particular, their presence can have a great impact on root development, fruit setting and grain filing, seed viability, and plant vigor and health. Micronutrient deficiency or toxicity can result in stunted growth, low yields, dieback, and even plant death. Micronutrients also benefit plants indirectly by feeding the microorganisms in the soil that perform important steps in various nutrient cycles of the soil plant root system. Of course, the end product is the role micronutrients play when the harvest reaches the table. Increasing evidence indicates that crops grown in soils with low levels of micronutrients may not provide sufficient human dietary levels of certain elements, even though the crops show no visual signs of deficiency themselves. These unseen deficiencies can readily be found through proper laboratory analysis, which will be discussed. The World Health Organization reports that micronutrient malnutrition contributes substantially to the global burden of disease. In 2000, the World Health Report identified iron and zinc deficiencies as being among the world’s most serious health risk factors. Micronutrient malnutrition is known or suspected to contribute to a wide range of impairments, including reduced resistance to infections, metabolic disorders, learning disabilities, and stunted development and growth of infants and children. Micronutrients and Soil Micronutrients occur naturally in soil minerals, which gradually break down from rock minerals and are released in forms that are available to plants. Some micronutrients are reintroduced to the soil during decomposition of organic matter from plants and animals. A critically important concept related to micronutrients is that of their availability to plants. Micronutrients can sometimes be present in soils but not in a chemical form that roots are able to absorb. Soil physical characteristics and environmental conditions play key roles in determining when and how available soil nutrients--especially micronutrients--are to plants. • Acid leaching can remove micronutrients from the soil, as can intensive cropping in which large amounts of plant nutrients are removed in the harvest. • High phosphorus availability in soil can diminish the availability and uptake of some micronutrients, particularly iron and zinc. • Extremes in soil pH can result in reduced micronutrient availability (Figure 1) or even cause micronutrient toxicity. Most plants have a pH range “sweet spot” in which the micronutrients in the soil are soluble enough to satisfy plant needs without becoming so soluble as to become toxic. • Plants grown on soils very low or very high in organic matter or with sandy or heavy clay texture can experience micronutrient deficiencies or imbalances. • Soil erosion can carry away humus and organic matter in which some micronutrients are held. • Cold, wet soil conditions can slow or stop plant root “Micronutrients are important both to crops and human health...”