Environmental Science PowerPoint Lecture Principles of Environmental Science - Inquiry and Applications, 1st Edition by William Cunningham and Mary Ann Cunningham

Chapter 7 - Topics Nutrition and Food Supplies Major Food Sources Soil: A Renewable Resource Ways We Use and Abuse Soil Other Agricultural Resources New Crops and Genetic Engineering Sustainable Agriculture

Part 1: Nutrition and Food Supplies World food supplies: 1950 vs In richer countries, the most common dietary problem is over-nutrition. Sub-Saharan Africa: food production has not kept pace with rapid population growth Asia has experienced the most rapid increase in crop production.

World Grain, Food Production

Food Security About 800 million people are chronically hungry (200 million are children). Food security - the ability to obtain sufficient food on a day-to-day basis Poverty is the greatest threat to food security. Within families that don’t get enough to eat, women and children have the poorest diets.

Countries at risk for inadequate nutrition The largest number of hungry people live in East and South Asia. Persistent hunger is also a major problem in Africa.

Essential Nutrients Malnourishment - a nutritional imbalance caused by a lack of specific dietary components or an inability to utilize essential nutrients Starchy foods like corn and polished rice tend to be low in several essential nutrients. Protein deficiency diseases - kwashiorkor, marasmus Iron deficiency - anemia - most severe in India Iodine deficiency - goiter, hyperthyroidism

kwashiorkormarasmus

Eating a Balanced Diet USDA Food Pyramid

Famines: Some Causes Environmental conditions - drought, insects, natural disasters National politics - corruption, oppression Armed conflict Economics - price gouging, poverty, landlessness

Dealing with Underlying Causes of Famine The aid policies of of rich countries often serve more to get rid of surplus food and make us feel good than to get at root causes of starvation.

Part 2: Major Food Sources Three major crops - wheat, rice, maize High latitudes - potatoes, barley, oats, rye Warm, wet areas - roots and tubers Dry regions of Africa - sorghum and millet Fruits and vegetables Crops

Meat, Milk, and Seafood Milk and meat highly prized, but distribution inequitable About 90% of the grain grown in North America is used to feed cattle, hogs, poultry, and other animals! Seafood - important protein source in many countries - threatened by overharvesting and habitat destruction

Annual Production of Some Important Foods

Part 3: Soil - A Valuable Renewable Resource Soil - a complex, living resource We depend on soil for life, yet tend to take it for granted. U.S. - at least 20,000 different soil types Building good soil is a slow process About 30-50% of the world’s croplands are losing topsoil faster than it can be replaced.

Soil Organisms Without soil organisms, the earth would be covered with sterile mineral particles.

Soil Profile

Part 4: Ways We Use and Abuse Soil Much potential cropland suffers from constraints.

Land Resources Cropland per person averages only 0.7 acre worldwide. By 2025, this could decline to 0.42 acre. In developed countries, 95% of recent agricultural growth has come from improved crop varieties or increased fertilization, irrigation, etc. Land conversion - ecological trade-offs

Worldwide Soil Degradation

Areas of Concern for Soil Degradation

Erosion: The Nature of the Problem Erosion - natural process, but a disaster when it occurs in the wrong place at the wrong time Rill erosion Gully erosion

Mechanisms of Erosion Most soil erosion on agricultural land is rill erosion Some of the highest erosion rates in the world occur in the U.S. and Canada - row crops leave soil exposed

Other Agricultural Resources Water - agriculture accounts for the largest single share of global water use Fertilizer - problems with excess use Energy - most of our foods require more energy to produce, process, and transport than they yield when we eat them Pesticides - serious concerns

Total Energy Use in U.S. Agriculture

Up to 90% of all pesticides never reach target organisms.

Part 5: New Crops and Genetic Engineering The green revolution So far, the major improvements in farm production have come from technological advances and modification of a few well-known species. “High responders”

Green Revolution “Miracle Crop” Yield

Genetic Engineering Genetic engineering -splicing a gene from one organism into the chromosome of another Transgenic organisms (GMOs) produced About one-third of U.S. corn and soybean crops are now transgenic. Pest resistance, weed control Public opposition to GMOs growing

Transgenic Crop Releases

Part 6: Sustainable Agriculture Sustainable agriculture (regenerative farming) - goal is to produce food and fiber on a sustainable basis and to repair damage caused by destructive practices Soil conservation - land management, ground cover, climate, soil type, tillage system important

Managing Topography Contour Plowing Strip-farming Terracing Planting perennial species

Providing Ground Cover

Reduced Tillage Minimum till Conserv-till No-till

Low-input Sustainable Agriculture

Organic and Locally Grown Foods