BESC 201 10 21 2013 Lecture 21 Outline of Last Lecture I Urban Sustainability Outline of Current Lecture II Chapter 7 Central Case Study III The Race to Feed the World IV The Changing Face of Agriculture V Soils Current Lecture 10 21 2013 Soil Agriculture and the Future of Food Central Case Study Iowa s Farmers Practice No Till Agriculture Turning the earth by tilling plowing disking harrowing or chiseling aerates the soil and works weeds and old crop residue into the soil to nourish it Tilling also leaves the surface bare allowing wind and water to erode away precious topsoil No Till Farming Rather than plowing after each harvest farmers leave crop residues atop their fields keeping the soil covered with plant material at all times To plant the next crop they cut a thin shallow groove into the soil surface drop in seeds and cover them Conservation Tillage an approach involving limited tilling The Race to Feed the World Food Security the guarantee of an adequate safe nutritious and reliable food supply available to all people at all times We face undernutrition overnutrition and malnutrition Undernutrition receiving fewer calories than the minimum dietary energy requirement Overnutrition consuming too many calories each day Malnutrition a shortage of nutrients the body needs occurs when a person fails to obtain a complete complement of vitamins and minerals Kwashiorkor a form of malnutrition from people who eat a diet that is high in starch but deficient in protein or essential amino acids Marasmus protein deficiency together with a lack of calories Some biofuels reduce food supplies These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Biofuels fuels derived from organic materials and used in internal combustion engines as replacements for petroleum In the United States ethanol produced from corn is the primary biofuel The use of corn for fuel production caused a scarcity of corn worldwide and prices for basic foods skyrocketed The Changing Face of Agriculture Agriculture the practice of raising crops and livestock for human use and consumption Cropland land used to raise plants for human use Rangeland land used for grazing livestock Industrial agriculture is a recent human invention Traditional Agriculture the work of cultivating harvesting storing and distributing crops performed by human and animal muscle power along with hand tools and simple machines Polycultures a mix of different crops in small plots of farmland Industrial Agriculture a faster and more powerful means of farming with the use of intensified irrigation and synthetic fertilizers Monocultures vast areas being planted with single crops in orderly straight rows When all plants in a field are genetically similar all are susceptible to viral diseases fungal pathogens or insect pests that can spread quickly from plant to plant Efforts have been made to conserve the wild relatives of crop plants and crop varieties indigenous to various regions because they may contain genes we will one day need to introduce into our commercial crops Seed Banks institutions that preserve seed types around the world including a doomsday seed vault Scientists want to avoid genetic contamination of wild populations so that we preserve the natural gene combinations of plants that are well adapted to their environments The Green Revolution boosted production and exported industrial agriculture Green Revolution introduced new technology crop varieties and farming practices to the developing world and drastically increased food production in these nations Norman Borlaug introduced a specially bred type of wheat to Mexico India and Pakistan and earned a Nobel Peace Prize The effects of industrial agriculture have been mixed High input industrial agriculture succeeded dramatically in producing higher crop yields from each hectare of land and reducing pressure to develop natural areas for new farmland Intensive application of water fossil fuels inorganic fertilizers and synthetic pesticides worsened pollution topsoil losses and soil quality Sustainable agriculture reduces environmental impacts Sustainable agriculture agriculture that maintains the healthy soil clean water and genetic diversity essential to long term crop and livestock production Treating agricultural systems as ecosystems is a key aspect of sustainable agriculture One key component of making agriculture sustainable is reducing the fossil fuel intensive inputs we devote to agriculture and decreasing the pollution these inputs cause Low Input Agriculture agriculture that uses lesser amounts of pesticides fertilizers growth hormones antibiotics water and fossil fuel energy than are used in industrial agriculture Soils Soil a complex system consisting of disintegrated rock organic matter water gases nutrients and microorganisms Soil forms slowly Soil formation begins when the lithosphere s parent material is exposed to the effects of the atmosphere hydrosphere and biosphere Parent Material the base geologic material in a particular location Bedrock the continuous mass of solid rock that makes up Earth s crust Weathering the physical chemical and biological processes that convert large rock particles into smaller particles Humus a dark spongy crumbly mass of martially decomposed organic matter material made up of complex organic compounds A soil profile consists of layers known as horizons Horizon each layer of soil Soil Profile the cross section as a whole from surface to bedrock Few soil profiles contain all six of these horizons but any given soil contains at least one of them Leaching the process whereby solid particles suspended or dissolved in liquid are transported to another location Topsoil consists mostly of inorganic mineral components with organic matter and humus from above mixed in O Horizon Organic litter layer A Horizon Topsoil E Horizon Eluviated leaching layer B Horizon Subsoil C Horizon Weathered parent material R Horizon Rock parent material Regional differences in soil traits affect agriculture Swidden Agriculture 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 At low population densities this can be sustainable but with today s dense human populations soils may not be allowed enough time to regenerate
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