Exam 2 Food and Ag Study guide
How does the use of fertilizers affect agriculture? What are the negative effects of overuse of fertilizers?
Plants require nitrogen, phosphorus, and potassium to grow, as well as smaller amounts of more than dozen other nutrients. Plants and leaching remove these nutrients from soil (as plants grow) which leads to a decreased yield in crops if too many nutrients are depleted. This is why farmers enhance soils with fertilizers; substances that contain essential nutrients. Industrialized nations and the Green Revolution brought about an embracing of inorganic fertilizers; mined or synthetically manufactured mineral supplements. These fertilizers have boosted our global food production, but their overapplication has triggered increasingly severe pollution problems. Because inorganic fertilizers are generally more susceptible to leaching and runoff than are organic fertilizers, they more readily contaminate surface water bodies and groundwater supplies. Other CONSEQUENCES: nutrients from inorganic fertilizers can have impacts far beyond the boundaries of the fields on which they are applied; nitrogen and phosphorus for example runoff from farms and other inland sources and spur phytoplankton blooms in the Chesapeake Bay, the Gulf of Mexico, and other marine and coastal regions, creating oxygen-depleted "dead zones" that kill fish and shellfish. Eutrophication: the process of nutrient over-enrichment, blooms of algae, increased production of organic matter, and subsequent ecosystem degradation. Components of some nitrogen fertilizers can even volatilize into the air, contributing to photochemical smog and acid deposition. Through these processes, unnatural amounts of nitrates and phosphates spread through ecosystems and can pose human health risks, including cancer and methemoglobinemia, a disorder that can asphyxiate and kill infants. HUMAN INPUTS OF NITROGEN HAVE MODIFIED THE NITROGEN CYCLE AND NOW ACCOUNT FOR ONE HALF THE TOTAL NITROGEN FLUX ON EARTH. Sustainable approaches include drip irrigation (adding fertilizer in there), no-till farming (conservation tillage), monitoring soil nutrient content Use organic fertilizers; consist of the remains or wastes of organisms and include animal manure; crop residues; charcoal; fresh vegetation; and compost; a mixture produced when decomposers break down organic matter such as food and crop waste in a controlled environment. Organic Fertilizers provide not only nutrients but also organic matter that improves soil structure, nutrient retention, and water-retaining capacity. Sustainable approaches do not rely solely on organic fertilizers nut integrate them with the targeted use of inorganic fertilizer
How much of the Earth's surface is currently cultivated?
38% of Earth's surface (12% cropland, 26% rangeland) US = 27% range, 19% crop=50%
Why is topsoil so important for agriculture?
A crucial horizon for agriculture and ecosystems is the A HORIZON or Topsoil. Topsoil consists mostly of inorganic mineral components, with organic matter and humus from above mixed in. Topsoil is the portion of the soil that is most nutritive for plants, and it takes its loose texture, dark coloration, and strong water-holding capacity from its humus content. The O and A horizons are home to most of the organisms that give life to soil. Topsoil is vital for agriculture, but agriculture practiced unsustainably over time will deplete organic matter, reducing the topsoil's fertility and ability to hold water. Humus: Partial decomposition of organic matter creates Humus, a dark, spongy, crumbly mass of material made up of complex organic compounds. Soils with high humus content hold moisture well and are productive for plant life.
How has biotechnology changed agriculture in terms of new varieties?
An organism that contains DNA from another species is called a transgenic organism and a gene transferred between them is called a transgene. The creation of transgenic organisms is one type of biotechnology, the material application of biological science to create products derived from organisms. Biotechnology has helped us develop medicines, clean up pollution, understand the causes of cancer and other diseases, dissolve blood clots after heart attacks, and make better beer and cheese. In genetic engineering, scientists use a process of mutation that is nonrandom and precisely directed. How techniques of geneticists differ from traditional selective breeding: (1) Scientists creating recombinant DNA routinely mix genes of organisms as different as viruses and crops, or spider and goats. (2) genetic engineering works with genetic material in the lab. (3) genetic engineering creates novel combinations directly in a more controlled way. In the 1980s, confidence grew that techniques were safe, industry leaped at the chance to develop hundreds of applications, from improved meds (such as hepatitis B vaccine and insulin for diabetes) to designer plants and animals (including glow-in-the-dark pet goldfish). Since then, GM crops have been adopted and planted across the world with remarkable speed. 4 of every 5 soybean plants in the world are transgenic, as are ¾ cotton plants, ⅓ corn plants, ¼ canola plants. 12% of world cropland grows GM crops. Estimated that 70% of processed foods in US stores contain GM ingredients. GM crops include RoundUp Ready crops (engineered to tolerate herbicides so that farmers can apply herbicides without having to worry about killing their crops). Other crops engineered to resist insect attacks. Some modified for both mentioned traits). Soybeans account for ½ GM crops in world. More than ½ are grown in developing countries. Notable developments in GM Foods: Golden Rice: engineered to produce beta-carotene to fight Vitamin A deficiency in Asia and the developing world. May only offer moderate nutritional enhancements :/ despite years of work. Virus-resistant Papaya: Resistant to ringspot virus. GM Salmon: for fast growth and large size. Would be first GMO animal approved for sale as food. To prevent fish from breeding with wild salmon and spreading disease to them, company AquaBounty promised to make their fish sterile and raise them in inland pens. Biotech Potato: Resistant to late blight, which still destroys $7.5 Billion potatoes each year. Bt Corn: engineered with genes from bacterium Bacillus Thuringiensis (Bt) that kills insects. Bt Cotton: engineered with genes from bacterium Bacillus Thuringiensis that kills insects. Has increased yield , decreased insecticide use, and boosted income fro 14 million small farmers in India, China, and other nations. Roundup-ready sugar beet and alfalfa: Tolerant of Monsanto's Roundup Herbicide (glyphosate). Biotech soybeans: The most common GM crop in the world, covering nearly half the cropland devoted to biotech crops. Engineered for herbicide tolerance, insecticidal properties, or both. May be "stacked" with more than one engineered trait.
What is the effect of overgrazing on the land?
As long as livestock populations do not exceed the rangeland's carrying capacity and do not consume grass faster than it can regrow, grazing can be sustainable. Without adequate regeneration of plant biomass, the result is overgrazing. When livestock remove too much plant cover or churn up the soil with their hooves, soil is exposed and made vulnerable to erosion. In a positive feedback cycle, soil erosion makes it difficult for vegetation to regrow, a problem that perpetuates the lack of cover and gives rise to more erosion. Too many livestock trampling the ground can also compact soil and alter its structure. Soil compaction makes it more difficult for water to infiltrate, for soil to be aerated, for plants' roots to expand, and for roots to conduct cellular respiration. Decrease plant growth and survival. Worldwide, overgrazing causes as much soil degradation as cropland agriculture does, and it causes more desertification. Degraded rangeland costs an estimated $23 billion per year in lost productivity. Most US rangeland is federally owned and managed by the Bureau of Land Management; nation's largest landowner (more than 248 million acres mostly in 12 western states - 1/10 of US land base) Ranchers can be granted rights to graze livestock on BLM lands for inexpensive fees; a grazing permit in 2016 was just $2.11 per month per "animal unit" (one horse, one cow plus calf, 5 sheep or 5 goats). As a result of these low fees, American ranchers have traditionally had little incentive to conserve rangelands. B/c most grazing has taken place on public lands leased from the government and because US taxpayers have subsidized grazing, a classic "tragedy of the commons" situation has developed, and overgrazing has resulted in extensive environmental impacts across the American West. POSITIVE: The conservation reserve program pays farmers to stop cultivating damaged and highly erodible cropland, and instead to place it in conservation reserves planted with grasses and trees. Internationally, the United Nations promotes soil conservation and sustainable agriculture through a variety of programs led by the Food and Agriculture Organization (FAO).
What is the Dust Bowl? How did these events affect the future of agriculture?
Before the large-scale cultivation of North America's Great Plains, native prairie grasses of this temperate grassland region held soils in place. In the late 19th and early 20th centuries, many homesteading settlers arrived in Oklahoma, Texas, New Mexico, and Colorado, hoping to make a living there as farmers. Between 1879 and 1929, cultivated areas in the region soared from 5 million ha to 40 million ha (12 to 100 million ha). Farmers grew abundant wheat and ranchers grazed many thousands of cattle, sometimes expanding onto unsuitable land and causing erosion by removing native grasses and altering soil structure. In early 1930, drought worsened ongoing human impacts, and the region's strong winds began to erode millions of tons of topsoil. Massive dust storms traveled up to 2000 km, blackening rain and snow as far away as New York and Washington DC. Some areas lost 4 inches in just a few years. Most affected region became known as "Dust Bowl", a term now used for the historical event itself. Many were forced to leave, most leaving west as refugees, adding to the economic hardship of the Great Depression. US Congress passed the Soil Conservation Act of 1935, which established the Soil Conservation service (SCS); worked closely with farmers to develop conservation plans for individual farms, using science to assess land's resources and problems - earliest example of INTERDISCIPLINARY environmental problem solving. SCS now named NRCS (National Resources Conservation Service)
What is a monoculture? Polyculture?
Born with the industrial revolution, monoculture: The cultivation of a single crop in a given area. 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 polycultures ("many types") typical of traditional agriculture, such as Native American farming systems that mixed maize, beans, squash, and peppers in the same fields.
What kind of techniques are used in agriculture today to reduce the loss of topsoil? Examples?
Crop Rotation: Rotating crops such as soybeans and corn helps restore soil nutrients and reduce impacts of pests. The process in which farmers alternate the type of crop grown in a given field from year to year (or season to season). For example, soy can revitalize the soil with nutrients with specialized bacteria on their roots that fix nitrogen. Rotating crops also reduces insect pests; if an insect is adapted to feed and lay eggs on one crop, then planting a different type of crop will leave its offspring with nothing to eat. Crop rotation also helps minimize the erosion that occurs when farmers let fields lie fallow (unplanted) Contour Farming: Contour farming reduces erosion on hillsides. Water running down a hillside with little plant cover can carry soil away, so farmers have developed methods for cultivating slopes. 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. The side of each furrow acts as a small dam that slows runoff and captures eroding soil. Terracing: Terracing minimizes erosion in mountainous areas. On very steep terrain, the most effective method for reducing erosion is terracing. Terraces are level platforms, sometimes with raised edges, that are cut into steep hillsides to contain water from irrigation or precipitation. Labor intensive but likely the only sustainable way to farm in mountainous terrain. Intercropping: Intercropping reduces soil loss and maintains soil fertility. Planting different crops in alternating bands or other spatially mixed arrangements. Helps slow erosion by providing more ground cover than does a single crop. Like crop rotation, intercropping reduces vulnerability to insects and disease and, when a nitrogen-fixing legume is included, replenishes the soil with nutrients. Shelterbelts: Shelterbelts protect against wind erosion. Windbreaks. Rows of trees or tall shrubs that are planted along the edges of fields to slow the wind. Poplars often used. Can be combined with intercropping; mixed crops are planted in rows surrounded by or interspersed with rows or trees that provide fruit, wood, and wildlife habitat, as well as protection from wind. No-till farming: for example, soybeans grow through stubble remaining from a wheat crop, in no-till agriculture. No-till farming is the ultimate form of Conservation tillage because it eliminates tilling altogether. Farmers leave crop residues atop their fields, keeping the soil covered with plant material. Use of "no-till drill" to cut shallow grooves and drops seeds into the furrow to plant the next crop. Less soil erodes away, organic material accumulates, and the soil soaks up more water - encourages plant growth. By adding organic matter to soil, carbon is stored in soil instead of releasing into the atmosphere (contributing to climate change). Reduces tractor use - farmers burn less gasoline. In US, ¼ of farmland is under no-till cultivation
What is the difference between cropland and rangeland?
Cropland is used to grow crops (plants), and range land is used to graze, herd, and house livestock. A LOT (1/3) of cropland goes towards feeding livestock
Describe soil. What are the components of soil?
Describe soil. What are the components of soil? Soil is a multifaceted system consisting of disintegrated rock, organic matter, water, gases, nutrients, and microorganisms. Although it is derived from rock, soil is shaped by living organisms. By volume, soil consists roughly of 50% mineral matter and up to 5% organic matter. The rest consists of the space between soil particles (PORE space) taken up by air or water. The organic matter in soil includes living and dead microorganisms as well as decaying material from plants and animals. The composition of a region's soil strongly influences the character of its ecosystems. In fact, because soil is composed of living and nonliving components that interact in complex ways, soil itself meets the definition of an ecosystem.
What is the role of desertification in regards to agriculture
Desertification describes a form of land degradation in which more than 10% of productivity is lost as a result of erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change, water depletion, and other factors. Most such degradation results from wind and water erosion. Can expand deserts or create new ones. There has been a dramatic desertification of fertile crescent over a long period of time. Desertification is expected to grow worse as climate change alters rainfall patterns, making some areas drier. By some estimates, desertification endangers the food supply or well-being of more than 1 Billion people in more than 100 countries and costs tens of billions of dollars in income each year. China alone loses $6.5 Billion annually from desertification.
What is erosion? How does it affect agriculture? What is the connection between topsoil and erosion? What is happening to the world's topsoil?
Erosion is the removal of material from one place and its transport to another by the action of wind and water. When eroded material is deposited at a new location, this is called deposition. Erosion and deposition are natural processes, and in the long run deposition helps to create new soil. For example, flowing water may deposit freshly eroded sediment rich in nutrients across river valleys and deltas, helping to form rich and productive soils. This is why floodplains are excellent for farming. Erosion can be a problem for ecosystems and for agriculture because it tends to occur much more quickly than soil is formed. Erosion also tends to remove topsoil, the most valuable soil layer for living things. And when eroded soils are carried out to sea, their nutrients are lost to terrestrial systems. Windy regions with sparse plant cover experience the most wind erosion, whereas areas with steep slopes, intense precipitation, and sparse vegetation cover suffer the most water erosion. Although erosion is a natural process, people have made land more vulnerable to erosion in 3 ways: (1) over cultivating fields through poor planning or excessive tilling (plowing), (2) Grazing rangeland with more livestock than the land can support, (3) Clearing forests on steep slopes or with large clear-cuts. In the long term, vegetation is what prevents soil loss. Vegetation slows wind and water flow while plant roots hold soil in place and take up water. More than 19 billion ha (47 billion acres) of the world's croplands suffer from erosion and other forms of degradation resulting from human activity. Human activities move over 10 times more soil than all natural processes combined. US farmlands lose roughly 5 tons of soil for every ton of grain harvested. In Africa, soil degradation in coming decades could reduce crop yields by half.
Describe traditional agriculture. How does it differ from modern practices (focus on the traditional aspect in your answer).
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. In the past, most traditional farmers produced only enough food for their own subsistence.
What is food security?
Hunger is also a problem in the US. USDA has classified 49 million Americans as "food insecure", lacking the income required to reliably procure sufficient food. Agricultural scientists and policymakers worldwide pursue a goal of food security; the guarantee of an adequate, safe, nutritious, and reliable food supply available to all people at all times.
What are the rapidly increasing consequences of the use of these modern technologies within agriculture (positive versus negative).
Industrial agriculture spread from developed nations to developing nations with the advent of the Green Revolution. Beginning around 1950, the GR introduced new technology, crop varieties, and farming practices to the developing world. These advances dramatically increased yields and helped millions avoid starvation. Yet despite its successes, industrial agriculture is exacting a price: The intensive cultivation of monocultures using pesticides, irrigation, and chemical fertilizers has many consequences, among them DEGRADATION OF SOIL, WATER, and POLLINATORS that we rely on for our terrestrial food supply.
What is the "Green Revolution"? Who is Norman Borlaug?
Industrial agriculture spread from developed nations to developing nations with the advent of the Green Revolution. Beginning around 1950, the Green Revolution introduced new technology, crop varieties, and farming practices to the developing world. These advances dramatically increased yields and helped millions avoid starvation. Yet despite its successes, industrial agriculture is exacting a price. The intensive cultivation of monocultures using pesticides, irrigation, and chemical fertilizers has many consequences, among them the degradation of soil, water, and pollinators that we rely on for our terrestrial food supply. Began in 1940s, when American agricultural scientist Norman Borlaug introduced Mexico's farmers to a specially bred type of wheat. This strain of wheat produced particularly large seed heads, was resistant to diseases, was short in stature to resist wind, and produced high yields. Within 2 decades of planting this new crop, Mexico tripled its wheat production and began exporting wheat. Norman Borlaug won the Nobel Peace Prize and took his wheat to India and Pakistan and transformed agriculture there as well.
Explain how the use of fossil fuel and modern technologies has changed the pattern of agriculture?
Industrialized Agriculture - increased yields - feed more mouths Machinery, fertilizers, pesticides, herbicides, pumps (for groundwater) Has led to destruction of habitats, removal of fresh water, loss of biodiversity, invasive species on the increase, pollution, loss of topsoil, desertification
How has modern irrigation affected agriculture?
Modern irrigation has allowed us to farm in arid regions and maintain high yields in times of drought. Fully 70% of all freshwater that people withdraw from rivers, lakes, and underground aquifers is used for irrigation. In some cases, withdrawing water for irrigation has depleted groundwater and dried up rivers and lakes. One of the most effective ways to reduce water use in agriculture is to better match crops and climate. Many arid regions have been converted into productive farmland through extensive irrigation, often with the support of government subsidies that make irrigation water artificially inexpensive. Another approach is to embrace technologies that improve efficiency in water use. Plants end up using only about 40% of the water we apply. DRIP IRRIGATION systems target water directly toward plant roots through hoses or tubes can increase efficiencies to more than 90%.
What are the different layers of soil? How do they differ from each other?
O Horizon - Organic (litter layer): organic matter deposited by organisms A Horizon - Topsoil: Some organic material mixed with mineral components E Horizon - Eluviated (leaching layer): Minerals and organic matter tend to leach out of this horizon. Minerals are transported downward as a result of leaching, the process whereby minerals suspended or dissolved in liquid are transported to another location. Soil that undergoes leaching is a bit like coffee grounds in a drip filter. When it rains, water infiltrates the soil, dissolves some of its components, and carries them downward. Minerals commonly leached from the E Horizon include Iron, aluminum, and silicate clay. In some soils, minerals may be leached so rapidly that plants are deprived of nutrients. Minerals that are leached from soils may enter groundwater, and some can pose human health risks when the affected water is extracted for drinking. B Horizon - Subsoil: Minerals and organic matter accumulate here C Horizon - Weathered plant material: initial step in soil formation R Horizon - Rock (parent material): bedrock, lava, etc.
Can we currently feed the world's 7.6 billion people? Explain.
Technically, yes. There is enough land to ensure no one on this planet goes hungry. Unfortunately, politics and money involved see that around 1 Billion people on this planet are hungry. Although this topic is hotly debated, we could even feed the whole world on organic food. Organic yields have been increasing as farmers gain more experience, and could increase further if the ****ing USDA made an effort - USDA currently sends only 2% of its research funding to organic agriculture. Moreover, experts argue that overall food production is not what limit our ability to feed the world. Only 43% of the global grain crop actually feeds people directly; the rest goes to livestock feed, BIOFUELS, and processed products like high-fructose corn syrup. Politcs and the logistics of transport limit food distribution, and ⅓ of all food intended for our consumption ends up going to waste. THUS - by reducing waste, eating less meat, dealing with distribution problems, and prioritizing food for people, the world could easily be fed by organic agriculture even with lower yields.
How has the world's food production fared over the last 50 years?
The Green Revolution introduced new technology, crop varieties, and farming practices to us as well as the developing world. Enormous growth in production Example: Norman Borlaug and Green Revolution allowed Mexico to triple wheat production. In India, intensified agriculture (high-input) saved millions in India from starvation in the 1970s and turned that nation into a net exporter of grain. Pros: intensifying the use of already cultivated land reduces pressures to convert additional lands for cultivation. Between 1961 and 2013, global food production more than tripled and per-person food production rose 48%, while area converted for agriculture only increased 11%. In this way, the Green Revolution helped preserve biodiversity and natural ecosystems by preventing a great deal of deforestation and habitat destruction. Cons: Intensified use of fossil fuels, water, inorganic fertilizers, and synthetic pesticides has worsened pollution, topsoil erosion, and soil and water quality. Globally the number of people suffering from undernutrition has been falling since the 1960s. The % of people who are undernourished has fallen even more.
What are the modern contributions to agriculture? How have these changed our ways of cultivating the land?
The industrial revolution introduced large-scale mechanization and fossil fuel combustion to agriculture, just as it did to industry. Many farmers in industrializing societies replaced horses and oxen with machinery that provided faster and more powerful means for 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 herbivory by crop pests and competition from weeds. Monocultures - 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. Polycultures - typical of traditional agriculture, such as Native American farming systems that mixed Maize, beans, squash, and peppers in the same fields.
What is salinization? Why does it occur? Consequences?
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. A more frequent problem is salinization, the buildup of salts in surface soil layers. In dryland areas where precipitation and humidity are low, the evaporation of water from the soil's A horizon may pull water containing dissolved salts up from lower horizons. As the water evaporates at the surface, those salts remain, often turning the soil surface white. Irrigation in arid areas generally hastens salinization, and irrigation water often contains some dissolved salt in the first place, which introduces new salt to the soil. Salinization inhibits crop production; it currently lowers yields on roughly one-fifth of all irrigated cropland globally, costing more than $11 billion each year. To alleviate salinization, stop irrigating and wait for rain to flush salts from the soil. However, in dryland areas where salinization is most often a problem, precipitation is rarely adequate to flush soils. BETTER SOLUTION: plant salt-tolerant plants, such as barley, that can be used for food or pasture. 3RD OPTION: Bring in large quantities of less-saline water to flush soil. However, using too much water may cause WATERLOGGING. Prevention is way better; remedying salinization once occurred is expensive and difficult - avoid planting crops that require a great deal of water in dryland areas. 2nd way: irrigate with water low in salt content. 3rd way: irrigate efficiently, supplying no more water than a crop requires.
What is over-nutrition? Where does it occur? Consequences?
We face undernutrition, overnutrition, and malnutrition Although 800 million people lack access to adequate food, many others consume more than is healthy and suffer from overnutrition, receiving too many calories each day. Overnutrition is a problem in developed nations such as the US, where food is abundant, junk food is cheap, and people tend to lead sedentary lives with little exercise. As a result, more than 1 in 3 US adults are obese, according to the CDCP. WHO estimates 39% of all adults in the world are overweight - of these, ⅓ obese. Excessive weight gain can lead to heart disease, diabetes, stroke, some types of cancer, other health problems. The growing availability of highly processed foods (which are often calorie-rich, nutrient-poor, and expensive) suggests that overnutrition will remain a challenge.
