Presentation on theme: "Land Use Part I: Agriculture. Food and Nutrition Foods humans eat are composed of several major types of biological molecules necessary to maintain health."— Presentation transcript:
Food and Nutrition Foods humans eat are composed of several major types of biological molecules necessary to maintain health : Carbohydrates – Sugars and starches metabolized by cellular respiration to produce energy Proteins – Large, complex molecules composed of amino acids that perform critical roles in body Lipids – Include fats and oils and are metabolized by cellular respiration to produce energy Vitamins and Minerals
Agricultural Land Use Agriculture now covers more of Earth’s surface than forests. – 38% of planet’s land surface is used for agriculture 26% pasture/rangeland 12% cropland
Using Land For Agriculture Humans need: – Most women need ~2,200 kilocalories / day – Men, ~ 2,900 kilocalories / day Biologists estimate that there are roughly 30,000 plant species with parts that humans can eat Majority of our food supply (90%) is derived from only 15 plant and 8 animal species Three grains, wheat, rice, and corn, provide almost half of the calories consumed by people – These three species are all annual plants 2 out of 3 people on Earth survive primarily on grains World food supplies have more than kept up with human population growth over the past two centuries. – During the past 40 years, population growth has averaged 1.7% per year, while food production increased an average 2.2%.
Chronic Hunger and Malnutrition Chronic undernutrition – Occurs when people cannot grow or buy enough food to adequately nourish themselves – Consequences: Mental retardation, stunted growth, increased susceptibility to infectious diseases Malnutrition – Occurs from low-protein diets that are common in countries where subsistence farming is the most common method of food production Nearly 6 million children die prematurely each year from undernutrition, malnutrition, and their effects.
Principle Types of Agriculture There are two Principle Types of Agriculture 1. Traditional Agriculture – Low Input Polyculture Human and animal labor used to produce only enough food for farming family’s survival 2. Industrialized agriculture High Input Monocultures – Produce huge output of single crops (monocultures) or livestock (which are often fed monoculture products)
Traditional Agriculture: Low Input Polyculture Many farmers in developing countries use low-input agriculture to grow a variety of crops on each plot of land (interplanting) through: – Polyvarietal cultivation Planting several genetic varieties. – Intercropping/Polyculture Two or more different crops grown at the same time in a plot.
Polyculture Agriculture Advantages of polyculture: – Crops mature and ready to harvest at different times – Provides food throughout the year – Soil constantly covered, preventing erosion – Less need for fertilizer and water because roots are at different depths, using more of soil and increasing efficiency – Creates habitats for natural predators of pest species, reducing need for pesticides and herbicides
Industrial Food Production: High Input Monocultures Requires large amounts of energy, water, fertilizers, antibiotics, and pesticides; three of which come from fossil fuels Produce huge output of single crops (monocultures) or livestock (which are often fed monoculture products) Accounts for roughly 25% of the world’s cropland Mostly in developed countries, but it is spreading into developing nations
Industrialized Food Production in the United States The U.S. uses industrialized agriculture to produce about 17% of the world’s grain. – Relies on cheap energy to run machinery, process food, produce commercial fertilizer and pesticides. About 10 units of nonrenewable fossil fuel energy are needed to put 1 unit of food energy on the table. Industrialized agriculture uses about 17% of all commercial energy in the U.S. and food travels an average 2,400 kilometers from farm to plate.
Sources of Protein -- Livestock One of the principal uses of animals in agriculture is to transform plant material into high-quality protein In traditional agriculture, livestock graze land, taking nutrients in and then they defecate and return some of the nutrients to the same field In industrial agriculture, livestock are fed grains (corn particularly, which they are not “designed” to do) and not necessarily in a field, so the manure does not fertilize a field Per capita meat consumption has increased 29% between 1950 and 1996 1/5 th of the world’s population consume roughly half of the world’s grain production through livestock
Sources of Protein -- Seafood Seafood is an important protein source. Since 1989, 13 of the 17 major fisheries in the world have declined or become commercially unsustainable. If current practices continue, the world’s fisheries will be exhausted by 2048. Aquaculture (growing aquatic species in pens) is providing an increasing share of the world’s seafood.
Green Revolution In 1960, 60% of the population of developing countries was considered chronically undernourished. – Fallen to less than 14% today Due to major improvements in farm production which came from technological advances and modification of a few well-known species. – Corn yields jumped from 25 bushels per acre to 130 per acre in last century. Most of gain accomplished through conventional plant breeding Green Revolution started by Norm Borlaug. – Promoted the use of dwarf, high yielding wheat and rice grown around the world. – Do require fertilizers and protection from pests. – Borlaug won Nobel Peace Prize.