Chapter 9 Review Sheets Key Terms agriculture bedrock clay compost Conservation Reserve Program conservation tillage contour farming cropland crop rotation deposition desertification Dust Bowl erosion fertilizer humus industrial agriculture inorganic fertilizers intercropping irrigation land degradation leaching loam monocultures no-till organic fertilizers overgrazing parent material pollination polycultures precision agriculture rangeland salinization sand shelterbelts silt slash-and-burn soil soil degradation soil horizon soil profile sustainable agriculture terracing topsoil traditional agriculture waterlogging weathering I. Central Case Study: Farm to Table—and Back Again—at Kennesaw State University A. In 2009, Kennesaw State University (KSU) opened The Commons, a dining facility that serves more than 5,000 students each day and was granted gold-level certification as a sustainable building by the Leadership in Energy and Environmental Design (LEED) program. The next year, KSU launched a Farm-to-Campus program when it acquired a plot of farmland just off campus. B. Today, the university runs three farms on 27 hectares (67 acres) of land near the campus that grow thousands of pounds of produce each year, supplying many of the fruits and vegetables served to students in The Commons. But KSU does even more and is working to create a fully closedloop system. C. KSU’s architects and engineers designed a facility that minimizes energy use, water consumption, and waste generation. D. With an award-winning green building as the anchor of its program, KSU set about creating an agricultural system that could supply diners with fresh, healthy, local produce. E. In addition, the university has cultivated relationships with local farms and meat producers, sourcing locally produced food whenever possible. F. KSU’s culinary program is receiving wide recognition, and in 2013 Kennesaw State became the first educational institution to win the National Restaurant Association’s Innovator of the Year award. G. Altogether, about 70% of America’s largest colleges and universities now have a campus farm or garden from which their dining halls can source food directly, according to a recent survey of more than 300 major institutions. II. The Changing Face of Agriculture A. Several factors underpin agriculture. 1. Agriculture is the practice of raising crops and livestock for human use and consumption. 2. We obtain most of our food and fiber from cropland—land used to raise plants for human use. 3. Rangeland, or pasture, is land used for grazing livestock. 4. Growing crops and raising animals require inputs of resources. Crops require soil, sunlight, water, nutrients, and mechanisms for pollination. Livestock require food and water. B. Agriculture led to modern societies. C. Industrial agriculture dominates today. 1. For thousands of years, the work of cultivating, harvesting, storing, and distributing crops was performed by human and animal muscle power, along with hand tools and simple machines—an approach known as traditional agriculture. 2. Farmers replaced horses and oxen with machinery that provided faster and more powerful means of cultivating, harvesting, transporting, and processing crops. Such industrial agriculture also boosted yields by intensifying irrigation and introducing synthetic fertilizers, while the advent of chemical pesticides reduced competition from weeds and herbivory by crop pests. a. The use of machinery created a need for highly organized approaches to farming, leading large-scale farmers to plant vast areas with single crops in straight orderly rows. Such monocultures (“one type”) are distinct from the polycultures (“many types”) typical of traditional agriculture, such as Native American farming systems, which mixed maize, beans, squash, and peppers in the same fields. 3. Beginning around 1950, the Green Revolution introduced new technology, crop varieties, and farming practices to the developing world. D. Sustainable agriculture reduces environmental impacts. 1. Sustainable agriculture describes agriculture that maintains the healthy soil, clean water, pollinators, and other resources essential to long-term crop and livestock production. III. Soil: A Foundation of Agriculture A. Soil is a living system. 1. Soil is a multifaceted system consisting of disintegrated rock, organic matter, water, gases, nutrients, and microorganisms. B. Soil supports agriculture. C. Soil forms slowly. 1. Parent material is the base geological material in a particular location. Bedrock is the mass of solid rock that makes up Earth’s crust. Parent material is broken down by weathering, the physical, chemical, and biological processes that convert large rock particles into smaller particles. 2. Once weathering has produced fine particles, biological activity contributes to soil formation through the deposition, decomposition, and accumulation of organic matter. a. Partial decomposition of organic matter creates humus, a dark, spongy, crumbly mass of material made up of complex organic compounds. 3. Weathering and the accumulation and transformation of organic matter are influenced by five main factors: climate, organisms, topography, parent material, and time. 4. Because forming just 1 inch of soil can easily require hundreds or thousands of years, we would be wise to conserve the soil we have. D. A soil profile consists of horizons. 1. As wind, water, and organisms move and sort the fine particles that weathering creates, distinct layers of soil eventually develop. Each layer is known as a soil horizon, and the cross-section as a whole, from surface to bedrock, is known as a soil profile. 2. The simplest way to categorize soil horizons is to recognize A, B, and C horizons corresponding respectively to topsoil, subsoil, and parent material. 3. Minerals are transported downward as a result of leaching, the process whereby minerals suspended or dissolved in liquid are transported to another location. 4. A crucial horizon for agriculture and ecosystems is the A horizon, or topsoil. E. Soils differ in quality. 1. Scientists classify soils—and farmers judge their quality for farming— based on properties such as color, texture, structure, and pH. a. A soil’s color can indicate its composition and its fertility. b. Soil texture is determined by the size of particles. i. Clay particles are less than 0.002 mm in diameter, silt of particles 0.002–0.05 mm, and sand 0.05–2 mm. ii. Soil with an even mixture of the three particle sizes is known as loam. c. Soil structure is a measure of the “clumpiness” of soil. d. Plants can die in soils that are too acidic or too alkaline, so soils of intermediate pH values are best for most plants. F. Regional soil differences affect agriculture. 1. The traditional form of agriculture in tropical forested areas is swidden agriculture, in which the farmer cultivates a plot for one to a few years and then moves on to clear another plot, leaving the first to grow back to forest. Plots are often burned before planting, in which case the practice is called slash-and-burn agriculture. IV. Water for Agriculture A. Irrigation boosts productivity. 1. The artificial provision of water beyond that which crops receive from rainfall is known as irrigation. B. Salinization and waterlogging are easier to prevent than to correct. 1. Waterlogging occurs when overirrigation saturates the soil and causes the water table to rise to the point that water drowns plant roots, depriving them of access to gases and essentially suffocating them. 2. A more frequent problem is salinization, the buildup of salts in surface soil layers. C. Sustainable approaches to irrigation maximize efficiency. V. Nutrients for Plants 1. Farmers enhance nutrient-limited soils by adding fertilizer, substances that contain essential nutrients. A. Fertilizers boost crop yields but can be overapplied. 1. There are two main types of fertilizers. a. Inorganic fertilizers are mined or synthetically manufactured mineral supplements. b. Organic fertilizers consist of the remains or wastes of organisms and include animal manure, crop residues, fresh vegetation (green manure), and compost, a mixture produced when decomposers break down organic matter such as food and crop waste in a controlled environment. B. Sustainable fertilizer use involves targeting and monitoring nutrients. 1. Precision agriculture involves using technology to precisely monitor crop conditions, crop needs, and resource use to maximize production while minimizing waste of resources. VI. Pollination 1. Pollination is the process by which male sex cells of a plant (pollen) fertilize female sex cells of a plant (ova, or egg cells). Pollination can occur in different ways. A. Many crops rely on pollinators. B. Protecting pollinators protects agriculture. VII. Conserving Agricultural Resources A. Damage to soil and land makes conservation vital. 1. Land degradation refers to a general deterioration of land that diminishes its productivity and biodiversity, impairs the functioning of its ecosystems, and reduces the services that these ecosystems provide to us. 2. Within the broad problem of land degradation, agricultural concerns often focus on what is known as soil degradation, the process by which soils deteriorate in quality and decline in productivity. B. Erosion threatens ecosystems and agriculture. 1. Erosion is the removal of material from one place and its transport to another by the action of wind or water. Deposition occurs when eroded material is deposited at a new location. 2. People have made land more vulnerable to erosion in three ways: a. Overcultivating fields through poor planning or excessive tilling. b. Grazing rangeland with more livestock than the land can support. c. Clearing forests on steep slopes or with large clear-cuts. 3. To minimize erosion, we can erect physical barriers that capture soil. C. Soil erosion is a global issue. D. Desertification reduces productivity of arid lands. 1. Desertification is a loss of more than 10% productivity due to soil erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change, water depletion, and other factors. 2. Desertification is expected to grow worse as climate change alters rainfall patterns, making some areas drier. E. The Dust Bowl prompted the United States to fight erosion. 1. In the early 1930s, a drought worsened the ongoing human impacts, and the region’s strong winds began to erode millions of tons of topsoil. The most affected region in the southern Great Plains became known as the Dust Bowl, a term now also used for the historical event itself. 2. In response, the U.S. government, along with state and local governments, increased support for research into soil conservation. The U.S. Congress passed the Soil Conservation Act of 1935, which established the Soil Conservation Service (SCS). 3. In 1994 the SCS was renamed the Natural Resources Conservation Service (NRCS), and its responsibilities were expanded to include water quality protection and pollution control. F. Farmers conserve soil and resources in many ways. 1. Crop rotation describes the process in which farmers alternate the type of crop grown in a given field from one season or year to the next. 2. Contour farming is a process in which furrows are plowed sideways across a hillside, perpendicular to its slope and following the natural contours of the land. 3. Terracing transforms slopes into series of steps like a staircase, enabling farmers to cultivate hilly land without losing huge amounts of soil to water erosion. 4. The planting of different types of crops in alternating bands or other spatially mixed arrangements is called intercropping. 5. Shelterbelts are rows of trees or other tall shrubs that are planted along the edges of fields to slow the wind. 6. Conservation tillage encompasses an array of approaches that reduce the amount of tilling relative to conventional farming. Notill farming— the ultimate form of conservation tillage—eliminates tilling altogether. Rather than plowing after each harvest, farmers practicing conservation tillage leave crop residues atop their fields, keeping the soil covered with plant material. G. Grazing practices affect soil quality. 1. When too many livestock destroy too much of the plant cover, impeding plant regrowth and preventing the regeneration of biomass, the result is overgrazing. H. Subsidies and conservation measures each influence ranching. I. Policy can promote conservation measures in agriculture. 1. The Conservation Reserve Program, first established in the 1985 Farm Bill, pays farmers to stop cultivating damaged and highly erodible cropland and instead to place it in conservation reserves planted with grasses and trees. 2. Internationally, the United Nations promotes soil conservation and sustainable agriculture through a variety of programs led by the Food and Agriculture Organization (FAO).
