Environmental Problems, Their Causes, and Sustainability 1

EcologicalServicesCroplands• Help maintain water flow andsoil infiltration•Provide partial erosionprotection• Can build soil organic matter• Store atmospheric carbon•Provide wildlife habitat forsome speciesNatural CapitalEconomicServices• Food crops• Fiber crops•Crop geneticresources• JobsFigure 14-3 Natural capital: ecological and economicservices provided by croplands.largest industry, providing a living for one of everyfive (1.3 billion) people.14-2 PRODUCING FOOD BY GREENREVOLUTION AND TRADITIONALTECHNIQUESHow Have Green Revolutions IncreasedFood Production? High-Input Monoculturesin ActionSince 1950, most of the increase in global foodproduction has come from using high-inputagriculture to produce more crops on each unitof land.Farmers can produce more food by farming more landor getting higher yields per unit of area from existingcropland. Since 1950, most of the increase in globalfood production has come from increased yields perunit of area of cropland in a process called the greenrevolution.The green revolution involves three steps. First,develop and plant monocultures (Figure 6-25, p. 118)of selectively bred or genetically engineered highyieldvarieties of key crops such as rice, wheat, andcorn. Second, produce high yields by using large inputsof fertilizer, pesticides, and water. Third, increase thenumber of crops grown per year on a plot of landthrough multiple cropping.This high-input approach dramatically increasedcrop yields in most developed countries between 1950and 1970 in what is called the first green revolution (Figure14-4, blue areas).A second green revolution has been taking placesince 1967. It involves introducing fast-growing dwarfvarieties of rice (Figure 14-5) and wheat (developed byNorman Bourlag, who later received a Nobel PeacePrize for his work) into several developing countriesin tropical and subtropical climates (Figure 14-4, greenareas). Producing more food on less land is also an importantway to protect biodiversity by saving large areasof forests, grasslands, wetlands, and easily erodedmountain terrain from being used to grow food.Yield increases depend not only on fertile soil andample water but also on high inputs of fossil fuels torun machinery, produce and apply inorganic fertilizersand pesticides, and pump water for irrigation. All told,high-input green revolution agriculture uses about 8%of the world’s oil output.Case Study: Industrial Food Productionin the United States: A Success StoryAmerica’s industrialized agricultural systemproduces about 17% of the world’s grain but hasa larger environmental impact than any otherAmerican industry.In the United States industrialized farming has becomeagribusiness as big companies and larger family-ownedfarms have taken control of almost three-fourths of U.S.food production. According to environmental educatorDavid Orr, “the U.S. food system is increasingly dominatedby ‘superfarms’, which are roughly to farmingwhat WalMart is to retailing.”In total annual sales, agriculture is bigger than theautomotive, steel, and housing industries combined. Itgenerates about 18% of the country’s gross national incomeand almost a fifth of all jobs in the private sector,employing more people than any other industry. Withonly 0.3% of the world’s farm labor force, U.S. farmsproduce about 17% of the world’s grain and nearlyhalf of the world’s corn and soybean exports.Since 1950, U.S. farmers have used green revolutiontechniques to more than double the yield of keycrops such as wheat, corn, and soybeans without cultivatingmore land. Such increases in the yield perhectare of key crops have kept large areas of forests,grasslands, wetlands, and easily erodible land frombeing converted to farmland.In addition, the country’s agricultural system hasbecome increasingly efficient. While the U.S. output ofcrops, meat, and dairy products has been increasingsteadily since 1975, the major inputs of labor and resources—withthe exception of pesticides—to produceeach unit of that output have fallen steadily since 1950.U.S. consumers now spend only about 2% of theirincome on domestically produced food, compared toabout 11% in 1948. Adjusted for inflation, U.S. farmproducts now cost about one-third of what they did in276 CHAPTER 14 Food and Soil Resources