1. Agricultural Practices 11/25/08

2. Irrigation The artificial provision of water to support agriculture –Rice and corn require large amounts of water, whereas beans and wheat require small amounts With irrigation, people have managed to farm in areas that are dry and previously unusable

3. Irrigation cont. 70% of all freshwater withdrawn by people is used for irrigation 683 million acres were irrigated in 2002 (greater than the area of Mexico and Central America)

5. Waterlogging The water table is raised to the point that plant roots are covered, depriving them of access to gases like oxygen Caused by overirrigation or poor drainage

6. Salinization The buildup of salts in surface soil layers Occurs as water evaporates from soil’s A horizon, pulling water from below and leaving the precipitated salts behind Inhibits agricultural production on 1/5 of irrigated cropland, costing more than $11 billion annually

7. Preventing salinization 1.Avoid planting crops that require a great deal of water in areas that are prone to salinization 2.Irrigate with water that is low in salt content 3.Irrigate efficiently, thus minimizing evaporation and salt accumulation

8. Solving Erosion Problems

9. Agricultural Fertilizers Two main types of fertilizers –Inorganic fertilizer—mined or synthetically manufactured mineral supplements –Organic fertilizer—natural materials (largely the remains or wastes of organisms) Includes animal manure, crop residues, fresh vegetation, and compost Often seen as a form of recycling

10. Food Security Food security means that every person in a given area has daily access to enough nutritious food to have an active and healthy life –Often depends on government assistance

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12. Chronic hunger and malnutrition We need fairly large amounts of macronutrients (such as protein, carbohydrates, and fats) and smaller amounts of micronutrients (vitamins and iron, calcium, etc) People who cannot grow or buy enough food to meet their basic needs suffer from chronic undernutrition

13. Chronic hunger and malnutrition Most chronically undernourished children live in developing countries –Likely to suffer from mental retardation, stunted growth, infectious diseases such as measles and diarrhea

14. Chronic hunger and malnutrition Malnutrition results from deficiencies of protein, calories, and other key nutrients –many poor live on low-protein, high- carbohydrate diets

15. Good news on hunger Since 1961, the average daily food intake per person in the world rose sharply –Estimates of chronically undernourished or malnourished people feel from 918 million in 1970 to 852 million in 2005, about 95% of them in developing countries

16. Bad news on hunger One in six people in developing countries (including about one of every 3 children younger than age 5) is chronically undernourished or malnourished Every year, 6 million children die prematurely from undernutrition –An average of 16,400 children die prematurely from these causes related to poverty

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18. Hunger in the United States In 2003, 35 million Americans (31 million in 1999) went hungry at times

19. The physiological effects of malnutrition Too little iron causes anemia –This causes fatigue, infections, and increases hemorrhages during childbirth

20. Physiological effects Iodine is essential for the thyroid gland, which produces hormones for metabolism –Found in seafood and crops grown in soil with iodine –Lack causes stunted growth, mental retardation, goiter –600 million people suffer from goiter, and 26 million children suffer brain damage a year from lack of iodine

21. Famine A famine occurs when there is a severe shortage of food in an area accompanied by mass starvation, many deaths, economic chaos, and social disruption –Often lead to mass migrations of people –Usually caused by crop failures from drought, flooding, war, and other catastrophic events

22. Solutions to hunger problems ½ to 1/3 of nutrition-related childhood deaths could be prevented at an average annual cost of $5-$10 –Immunizing children against childhood diseases –Encouraging breast-feeding –Preventing dehydration from diarrhea by giving a mixture of sugar and salt water –Preventing blindness by giving children a vitamin twice a year ($0.75) –Fortifying common foods with vitamins –Increasing education for women

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