植物营养元素的土壤化学土壤中的微量元素详解演示文稿
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The trend toward high-analysis fertilizers has reduced the use of impure salts and organic manures, which formerly supplied significant amounts of micronutrients.
The extent of micronutrient-deficient soils are comparable to that of nitrogen-, phosphorus-, and potassium-deficient soils. Summary data (Table 1) from an extensive effort that examined 190 soil samples from 15 countries revealed that 49% of these soils were low in zinc and 31% low in boron (Sillanpaa, 1990).
Other micronutrient deficiencies (e.g., Zn, Se, vitamin C, vitamin D, and folic acid deficiencies) may be as wide spread as iron, iodine and vitamin A deficiencies, but there are no reliable data to confirm this although circumstantial evidence suggests that this may be so (Combs et al., 1996; World Health Organization, 1999).
ຫໍສະໝຸດ Baidu
The most important sources of heavy metals in soils are those connected with anthropogenic activities, such as metal mining and smelting, production and usage of pesticides and wood preservatives, waste processing and disposal, etc.
植物营养元素的土壤化学土壤 中的微量元素详解演示文稿
（优选）植物营养元素的土壤 化学土壤中的微量元素
为何微量元素营养问题越来越重要？
Intensive plant production practices have increased crop yields, resulting in greater removal of micronutrients from soils.
Increased knowledge of plant nutrition and improved methods of analysis in the laboratory are helping in the diagnosis of micronutrient deficiencies that might formerly have gone unnoticed.
Welch R M. The impact of mineral nutrients in food crops on global human health. Plant and Soil 247: 83–90, 2002.
Figure 1. Global distribution of Fe, vitamin A and I deficiencies (map modified from Sanghvi, 1996).
对人体健康的影响？
Today, there are over 3.7 billion iron-deficient individuals and about 1 billion people that are or are at risk of developing iodine deficiency disorders. Additionally, there are over 200 million people that are vitamin A deficient (World Health Organization, 1999).
Toxicity of some micronutrient in soils.
Expanding interests in the field of heavy metal research were associated with increasing worldproduction of metals and their common usage in the past century, and consequently, with their increasing emissions into the environment. This resulted in growing hazard to human’s health posed by elevated metal concentrations in air, water, and food.
Increasing evidence indicates that food grown on soils with low levels of trace elements may provide insufficient human dietary levels of certain elements, even though the crop plants show no signs of deficiency themselves.
The extent of micronutrient-deficient soils are comparable to that of nitrogen-, phosphorus-, and potassium-deficient soils. Summary data (Table 1) from an extensive effort that examined 190 soil samples from 15 countries revealed that 49% of these soils were low in zinc and 31% low in boron (Sillanpaa, 1990).
Other micronutrient deficiencies (e.g., Zn, Se, vitamin C, vitamin D, and folic acid deficiencies) may be as wide spread as iron, iodine and vitamin A deficiencies, but there are no reliable data to confirm this although circumstantial evidence suggests that this may be so (Combs et al., 1996; World Health Organization, 1999).
ຫໍສະໝຸດ Baidu
The most important sources of heavy metals in soils are those connected with anthropogenic activities, such as metal mining and smelting, production and usage of pesticides and wood preservatives, waste processing and disposal, etc.
植物营养元素的土壤化学土壤 中的微量元素详解演示文稿
（优选）植物营养元素的土壤 化学土壤中的微量元素
为何微量元素营养问题越来越重要？
Intensive plant production practices have increased crop yields, resulting in greater removal of micronutrients from soils.
Increased knowledge of plant nutrition and improved methods of analysis in the laboratory are helping in the diagnosis of micronutrient deficiencies that might formerly have gone unnoticed.
Welch R M. The impact of mineral nutrients in food crops on global human health. Plant and Soil 247: 83–90, 2002.
Figure 1. Global distribution of Fe, vitamin A and I deficiencies (map modified from Sanghvi, 1996).
对人体健康的影响？
Today, there are over 3.7 billion iron-deficient individuals and about 1 billion people that are or are at risk of developing iodine deficiency disorders. Additionally, there are over 200 million people that are vitamin A deficient (World Health Organization, 1999).
Toxicity of some micronutrient in soils.
Expanding interests in the field of heavy metal research were associated with increasing worldproduction of metals and their common usage in the past century, and consequently, with their increasing emissions into the environment. This resulted in growing hazard to human’s health posed by elevated metal concentrations in air, water, and food.
Increasing evidence indicates that food grown on soils with low levels of trace elements may provide insufficient human dietary levels of certain elements, even though the crop plants show no signs of deficiency themselves.