2Chapter Seven Topics Food and Nutrition Major Food Sources Soil: A Renewable ResourceWays We Use and Abuse SoilOther Agricultural ResourcesNew Crops and Genetic EngineeringSustainable AgricultureTopics for Chapter Seven include the following: human nutrition and the supplies of food; major sources of food; soil which is the major resource used for agriculture; ways we use and abuse soil (agriculture is renewed but soil isn't); other agricultural resources; the development of new crops (in particular, role of genetic engineering in agriculture); and, what would encompass agriculture that is sustainable.
3Part 1: Nutrition and Food Supplies Chronic Hunger and Food Security - within families that don't get enough to eat, women and children have the poorest diets.World food supplies: 1950 versus 2000Richer countries: the most common dietary problem is over-nutrition (obesity)Sub-Saharan Africa: food production has not kept pace with rapid population growthAsia: most rapid increase in crop production and this accompanied rapid population growthAlthough issues with nutrition and food supplies seem abstract to us in wealthy countries, they are life and death issues for most people in the world. For this section, we'll consider the supply of food from 1950 until 2000 (a 50 year period with lots of data in terms of supplies and production), and we'll find out from where the food originates. Too much poor quality food (an issue in malnutrition in its own right) is the biggest dietary problem in the richest countries. In stark contrast, in Sub-Saharan Africa the food supply has not kept pace with population increase. Another scenario is what has happened in Asia where a fairly rapid population increase has gone hand-in-hand with a capacity to increase their food supply.Poverty and lack of social status are the greatest threats to food security (the ability to obtain sufficient food on a daily basis). About 1 in 5 people in the developing world are considered chronically undernourished. According to the United Nations Food and Agricultural Organization (FAO), 55% of the 12 million child deaths that occur annually are related to malnutrition. The world as a whole already grows enough food to provide everyone here > the 2,770 calories per day needed (on average) for a healthy, active life. Even so, more than 800 million people (of which there are 200 million children) are chronically undernourished (that is they receive < 90% of the minimum caloric intake needed for normal growth and development and a healthy, productive life).These are a few facts related to food security or the ability of an individual, town, country or whatever to maintain food available in quantities required to keep people healthy. This means more than just skipping a meal; rather, they may skip a day or more without enough food. This particularly has a big impact on children who are growing and developing. Adequate nutrition is completely necessary for them to be healthy. The human body has enough calories and protein to maintain and repair itself. Any one who has lived in a third world country knows what I'm talking about. For instance in the Peace Corps one of the first things we learned was how to get enough protein. Without adequate protein, people are unable to even repair itself and fend off disease. I actually had a counter part in Tanzania whose sister got an infection from a small wound and died. Poverty is the biggest problem in food security. Generally there is food available in most societies, but wealthy families get more than their necessary share. Typically it is children and women who don't have enough food. This was very true in Tanzania where I lived. Men got the first dibs on food and women and children came after that.
4Countries at risk for inadequate nutrition On the left is shown the number and proportion of chronically undernourished people in developing regions. The most hungry people live in East and South Asia. Persistent hunger is a major problem in Africa where the problem is getting worse.This slide shows countries in the world where the largest number of people are hungry on a day-to-day basis and don't have adequate nutrition. Notice that in Sub-Sahara Africa almost every country has some problem with adequate nutrition (in particular, countries like Tanzania, Ethiopia). Often countries in Asia have problems as well. Very few temperate areas have countries with significant problems with the exception of the area representing the former Soviet Union. In Europe, the United States and Canada hunger is not a persistent problem.
5Environmental conditions - drought, insects, natural disasters Famines are characterized by large-scale food shortages, massive starvation, social disruption, and economic chaos. Some causes are:Environmental conditions - drought, insects, natural disastersNational politics - corruption, oppressionArmed conflictEconomics - price gouging, poverty, landlessnessThe history of many cultures is full of examples of famine and its impact on societies. Famines are basically periods of time when not enough food is available on a large scale to feed people in a population. They are brought along typically by environmental conditions that may be an immediate trigger, but politics and economics are often underlying problems. For instance, some areas of the world are subject to drought, in particular some areas of Sub-Sahara Africa, India and China.Mass migrations often occur because productive capacity has been sacrificed. I am particularly familiar with the writings of Jorge Amado in Brazil who is always describing how the people of northeast Brazil are experiencing famine and migrating to southern parts of Brazil. Politics or war can often cause famine. Arbitrary political boundaries block historic access to refuge areas. Politics associated with corruption and oppression can lead to famine being used as a weapon of oppression. Denying food to the enemy in war can often lead to an advantage for one side over the other. In many cases countries are not wealthy enough to buy food.During famines the aid that is distributed from rich countries often is simply surplus commodities. Such actions produce feelings of generosity among populations of the wealthy countries. Food camps created by such distributions, however, have serious drawbacks. They can result in stress and crowding, lack of sanitation and bring many people into close contact with epidemic diseases.
6Essential NutrientsMalnourishment - a nutritional imbalance caused by a lack of specific dietary components or an inability to utilize essential nutrientsStarchy foods like corn and polished rice tend to be low in several essential nutrients.Protein deficiency diseases - kwashiorkor, marasmus (see next slide).Iron deficiency (anemia) - is the most common dietary deficiency in the world and is most severe in India.Iodine deficiency - causes goiter, hyperthyroidismAnother world problem is what we call mal-nourishment. In many cases although there are sufficient food and calories available, this food does not provide all the necessary nutrients and protein that the body needs. For instance in situations where only corn or polished rice are the staples with very little else available, nutrient deficiencies can be a problem. Certain elemental deficiencies are commonplace in some areas of the world (for example, selenium in China and iron in India). Iron deficiency is exemplified by anemia meaning the blood is unable to carry a sufficient amount of oxygen because iron is a center piece for the heme molecule. Anemia increases risk of death from hemorrhaging in childbirth and affects the physical and mental development of children (post- and pre-natal). Good sources of iron in diets include red meat, eggs, legumes, and green vegetables. Another mal-nourishment problem is iodine deficiency. It results in the swelling of the throat and hyperthyroidism (over activity of the thyroid) resulting in growth problems.
7Protein Deficiency Diseases Protein deficiency diseases are very common in Africa. For instance the extended belly of a disease called kwashiorkor is very, very common in poverty stricken areas with lots of children. Marasmus is a wasting away of the muscles that are used to provide energy for the body resulting in tight skin, sunken eyes and low energy. These pictures show the effects on children of kwashiorkor (extended belly disease) and marasmus (wasting disease). The main symptoms of kwashiorkor are reddish-orange hair and a bloated stomach. The main symptoms of marasmus is extreme thinness and a shriveled appearance.Kwashiorkor - "Displaced Child" - Occurs mainly in children whose diet lacks high-quality protein.Marasmus - "To Waste Away" - Caused by a diet low in both protein and calories.
8Obesity - The most common dietary problem in wealthy countries is over-nutrition. The US has a policy of over-production of food. Up to 61% of all adult Americans are overweight, while in poorer countries, people often cannot afford to purchase an adequate variety of foods, including meats and vegetables. One of the internal problems we face is that we have to do something with this food; therefore, we super-size our meals. We end up with so much cheap food that overeating and obesity are our most serious health problems. This is used as a way to make money for the US and also to provide food aid. If we did not have enough food to eat in our country, it would be hard to export our food. As noted earlier, getting rid of this excess US food does make us feel good. Another problem with this aid policy is that if other countries and people become over-dependent on this food, their own systems of producing food don't have to support them. In some cases this can lead to rather vicious cycles of poverty and malnutrition..
9PART 2: MAJOR FOOD SOURCES CropsWheat, rice and maize) are responsible for the majority of the world's nutrients.Potatoes, barley, oats and rye are staples at high latitudes with cool, moist climates.Potatoes, barley, oats and rye are staples in cool, moist climates.Cassava, sweet potatoes, and other roots and tubers are staples in warm wet climates.Sorghum and millet are drought resistant and staples in dry regions of Africa.Fruits, vegetables and vegetable oils contain high levels of vitamins, minerals, dietary fiber and complex carbonhdrates.There really are only a few major sources of food that feed most of the world's people. The major crops are wheat, rich and maize (corn). These big three produce more than one-half of the world's food. In cooler, higher latitudes potatoes, barley, oats and rye are the staples. In very hot tropical areas cassava and other tubers provide a large amount of calories and become the staples. In the very dry areas of Africa, corn and beans are the typical staples. Where it is dry corn and beans don't grow well, so oftentimes sorghum and millet are planted instead of or as a supplement to corn and beans. Fruits and vegetables are also grown to supplement the diet and make it more balanced.
10Annual Production of Important Foods Below - Rice plants (a type of grass or grain)This table shows the world production of some different, important food types. Notice that wheat, rice and maize (corn) are very, very large in terms of staple (high caloric) food types. Potatoes come in pretty high. Casava and sweet potatoes are important in tropical areas. Sugar is sometimes used as a staple although sucking on sugar cane is generally not a good source of nutrients other than calories and can cause all kinds of problems. Notice that more metric tons of vegetables and fruits are produced than other foods. Oftentimes fruits and vegetables don't have very high caloric content. An enormous amount of meat and milk are produced. Fish and seafood are a much smaller amount of the world's food although locally they can produce a large amount of the diet of some people.To the right is a picture from a field of rice. Grains (members of the grass family of plants) such as rice, wheat and maize are the most important dietary staples in the world. Rice, however, must be supplemented with other sources of vitamins, minerals and proteins. Scientists have attempted to use genetic engineering into rice to solve the problem of vitamin A deficiency in less developed countries. This deficiency results in the deaths of a million children each year and blindness in 350,000 more. European scientists were able to incorporate genes for synthesizing beta carotene (a functional precursor to vitamin A – a solution to this nutritional deficiency) into rice from daffodils. They did this by mixing relevant daffodil genes with bacterial DNA promoters using the soil bacterium Agrobacterium tumefaciens. The transgenic agrobacteria was incubated with rice embryos in a plant tissue culture medium. These bacteria infected the rice cells and transferred the genes that encode for the production of beta carotene. This is our first substantial discussion of genetically modified organisms. At the end of this chapter we will discover that GMOs are becoming an increasingly prevalent topic in environmental science.
11Eating a Balanced Diet as Determined by USDA Food Pyramid Even in countries that have large amounts of food available to their populations, malnutrition can be a problem. For instance, the U.S. probably has per capita as much food available as any other country in the world. Foods of various kinds can be too high in sugar and fats in America. So, the reality is that Americans have poor diets even though they have plenty of foods of various types. In particular, the USDA has constructed what they call a food pyramid that shows how humans, in theory, should eat in order to maintain a healthy, balanced diet.The basis for a balanced diet in this food pyramid is breads and cereals, pasta and staples. It should include lots of vegetables and fruits and a lesser amount of milk and meat that tend to be high in fats. Things like sugar and butter should be used in small amounts since they are too high in fat (up to 50%). The reality is that Americans eat out of the top three of these groups. Americans are dying of overnutrition (too many calories) or of eating too much food rather than too little. Madeline Albright (former Secretary of State) gave the commencement speech to UW in June of She talked of how in her travels she has seen 3 different worlds. In one world no matter how hard people work they cannot get enough to eat and are constantly suffering from malnutrition. In the second world, if they work hard they can get enough to eat and have a moderate standard of living; yet, still a fair amount of luck is involved in getting enough to eat. In the third world diet coke is a staple. I'm sure you know into which category the U.S. falls.
12Meat, Milk, and SeafoodMilk and meat are highly prized, but their distribution is inequitable. Developed countries make up 20% of world population, but consume 80% of meat and milk production. Less developed countries produce 60% of world's milk and meat.About 90% of the grain grown in North America is used to feed cattle, hogs, poultry, and other animals!Seafood is an important protein source in many countries. This food source is threatened by over-harvesting and habitat destruction.Animal protein (this includes milk, meat and seafood) provides a smaller amount of the world's food supply although from living in the US you would not necessarily think this was true. One of the problems in agriculture is that a vast majority of the grain is lost in production of meat and milk because in the U.S. 90% of the grain grown (including most of the corn and soybeans) is used to feed cows, poultry and other animals.Seafood is a food source separated from soil for production. As seafood utilization has expanded, over-harvesting and habitat destruction has resulted. In particular in Southeast Asia dependency on the production of shrimp has resulted in the destruction of wetland habitats. Annual catches of ocean fish rose by 4% annually between Since 1989, 13/17 major fisheries have declined or become commercially unviable.
13Environmental Issues with Raising Beef Every 16 kg of grain and soybeans fed to beef cattle in feedlots produce 1 kg of edible beef.If we ate grain directly, we would obtain twenty-one times more calories and eight times more protein than we get eating the beef.In the background of this picture you can see a mound of manure generated by this feedlot. Besides the inefficient loss of food from feeding cows, the large amount of manure produced causes environmental problems. Cows raised in feedlots produce lots of methane - a greenhouse gas that is much more efficient than carbon dioxide at trapping heat on the earth's surface. This feedlot approach is in sharp contrast to the method of raising cows shown on the title page of this chapter where cows are raised solely on a diet of grass (pastoral). Sometimes in feedlots, scrap pieces of meat are mixed in with the regular feed. This cannibalism can result in the spread of prions [proteins that cause a family or irreversible, degenerative neurological diseases known as transmissible spongiform encephalopathies (TSE)]. Just recently, this led to the appearance of Mad Cow Disease is cows in Washington State. Although this disease has not caused major problems here to date, it did result in the deaths of >125 people and the slaughter of 5 million cattle and in Europe in the 1990's. We will talk more about such emergent ecological diseases in Chapter 8 to follow.
14PART 3:SOIL - A VALUABLE RESOURCE Soil - a complex mixture of weathered minerals, partially decomposed organic matter and a host of living organismsWe depend on soil for life, yet tend to take this living resource for granted.U.S. has > 20,000 different soil types that vary due to influences of parent material, time, topography, climate and organismsAbout 30-50% of the world's croplands are losing topsoil faster than it can be replacedSoil is a renewable resource, but building good soil is a slow process.No consideration of food supply can be made without considering the material that produces the vast majority of food in the world – soil. Soil is a non-renewable resource from the standpoint that if you destroy it can be gone for long, long periods of time; but soil can renew many other resources (crops, trees, etc.). Soil is a complex, living substance. It is not dead, and the definition of soil does not include anything dead. We depend on soil for the vast majority of the food we grow, yet we tend to take for granted that it will always be there. In the US the Department of Agriculture has documented 20,000 types of soil. Improving soil once it has been damaged or destroyed is a very slow process that can take hundreds of thousands of years. One alarming fact is that topsoil (the most fertile part of the soil) is being lost in areas used for agriculture at a rate greater than it can be replaced.
15Soil Organisms Without soil organisms, the earth would be Soil is a storehouse of many, many organisms. It has been estimated that in the Pacific Northwest for instance 10 times as many organisms live in soil as above ground. The bio-complexity of soil and the organisms in it is greater than most bio-diverse rainforests above ground. All this bio-complexity leads to very diverse and interesting ecosystems about which little is known. One of the problems is that it is very difficult to look and study underground compared to looking at animals and plants above ground.Without soil organisms, the earth would becovered with sterile mineral particles.
16Soil Profile - soils are stratified into horizontal layers called soil horizons,and together theymake up the soilprofileOne of the main features of soil is what we call the soil profile. This can be seen when we dig a hole or in a road-cut, or any case in which we can work down through a soil profile from the surface into the lower reaches of the soil. These have distinctive properties. If we go deep enough into the soil it is typically little changed from what we call the parent material. As we get closer to the soil surface it is changed more than what it was originally. The addition of organic matter such as plant roots and other organisms affect it more. What we find at the surface of the soil typically bears very little resemblance to the original parent material and is a microbial, mite soup of intense microbiological activity.
17PART 4: WAYS WE USE & ABUSE SOIL Approximately 11% of the earth's land area is currently in agricultural production.Up to four times as much could potentially be converted to agricultural use.Much of this additional land suffers from constraints.One of the biggest problems we have in the world with food and agriculture is the mismanagement of soils. Many, if not most croplands of the world, are managed in such a way that they are degraded over time. This example shows severe wind erosion that has basically depleted the soil by removing the topsoil resulting in total de-vegetation of an area that is being cultivated for crops.Much potential cropland suffers from constraints.
18Land ResourcesCropland per person averages only 0.7 acres worldwide. By 2025, this could decline to 0.42 acres.In developed countries, 95% of recent agricultural growth has come from improved crop varieties or increased fertilization, irrigation, etc.Land conversion involves ecological trade-offsMany developing countries are reaching limit of lands that can be exploited for agriculture without unacceptable social and environmental costs.Availability of cropland for growing food is a finite resource. Right now the amount of cropland in the world averages about 0.7 acres per person. So, that 0.7 acres is expected to grow all the food that's required to feed a person. Certainly, in many cases it can overproduce food. In other cases this might be quite marginal in terms of cost. One of the problems that's faced in agriculture is that over the next 25 years that amount of land could be reduced to about 0.42 acres/person.Another thing that we have seen is that there has been a large increase in the productivity of food per acre. 95% of agricultural growth that we've seen has involved improved crop varieties, the use of fertilization, irrigation of crops and other technological inputs. Less land cultivated in NA now than 100 years ago.In many cases these may actually mask the degradation of the land. In terms of converting land, say natural systems into agricultural systems, we face many ecological tradeoffs. It has been said that we should revert back to a state of much, much lower technological application to agriculture. If we did this, we would actually need to increase the amount of land we delegate to agriculture That increase would come at the expense of the agricultural reserves, wilderness areas and other places we just described in previous chapters.
19Areas of Concern for Soil Degradation This slide shows areas of the world that are of concern in terms of soil degradation. The red areas are the areas most potentially damaged by erosion. These include, you might notice, most of the US is included as an area of serious concern in terms of the amount of soil erosion that is happening. Partly because there is so much agriculture practiced in the US and partly because either wind or water erosion rates can be high where this kind of agriculture is being practiced. Notice the PNW in particular because of the relatively gentle rain where agriculture is being practiced and, due to this low rainfall, it is not an area of particular concern. Notice also that essentially all of Africa with few exceptions has areas of serious concern for soil erosion. Most of the important agricultural regions of Europe are also areas of serious concern relative to soil degradation. Most of this is because of soil erosion.
20Erosion: The Nature of the Problem Erosion is an important natural process, resulting in redistribution of the products of geologic weathering, and is part of both soil formation and soil loss.Tends to begin subtly.Worldwide, erosion reduces crop production by equivalent of 1% of world cropland per year.Erosion is probably the most serious threat to soil degradation because the topsoil (the most fertile and productive part of the soil profile) is removed and transported elsewhere. Erosion is a natural process because it is carried out by gravity, water, and wind; but, it is a disaster when it is occurring in agricultural areas because it removes the productive capacity of the land. Two basic types of erosion: rill erosion where the surface of the land is removed relatively uniformly; and, gully erosion where water collects in a certain area and forms a small stream (or in some cases a torrent) and channels the land moving the water deeper and deeper into the profile. The next slide will deal in more detail with these mechanisms of erosion.
21Mechanisms of ErosionSheet Erosion - Thin, uniform layer of soil removed.Rill Erosion - Small rivulets of running water gather and cut small channels in the soil.Gully Erosion - Rills enlarge to form channels too large to be removed by normal tillage.Streambank Erosion - Washing away of soil from established stream banks.Wind and water are the two major agents that move soil and cause erosion. Wind can exceed water in erosive force in dry climates in areas with little topographic relief. Wind can transport soil from one continent to another. For instance dust from China's spring plowing can be easily detected in North America. Erosion can cause soil loss and lower the land's potential for farming or it can build soil as was the case in the Nile River delta that nurtured thousands of years of replenishable farm land for Egyptians. Most soil erosion on agricultural land is rill erosion and is most damaging when it carries away the topsoil. Applying additional fertilizer or moving cultivation to new areas are ways of compensating for erosion of productive fields. Erosion also causes sediment loading of rivers and lakes, siltation of reservoirs, smothering of wetlands and coral reefs, clogging of water intakes and waterpower turbines, and locally, suffocation of salmon fish eggs in creek and river beds.Streambank erosion often occurs as a result of removing of riparian trees and brush along the streambanks and by cattle damaging the banks. Streambank erosion can damage fish habitat by decreasing the amount of vegetative cover, channelizing the stream and lowering oxygen content of the water. In the Pacific Northwest there are many streambank stabilization and enhancement projects. Carkeek Park in Northwest Seattle has a particularly good salmon recovery program and is open for viewing by the public.Due to intensive farming practices, the U.S. and Canada have high erosion rates. Practices such as deep plowing, row crops, heavy herbicide applications and plowing straight up and down a slope (versus along the contour) all contribute to increased erosion. The North Plain of China and the Palouse in eastern Washington have very high erosion rates in soils that were originally deposited by wind (loess).
22Mechanisms of Erosion (continued) Wind can equal or exceed water as an erosive force, especially in a dry climate and on flat land.Intensive farming practices:Row crops leave soil exposedWeed free-fieldsRemoval of windbreaksNo crop-rotation or resting periodsContinued monoculturesAfter the 1930's dustbowl of the Midwest and West US, a great deal of effort was made to control soil erosion including the birth of the Soil Conservation Service that has now been renamed as the Natural Resources Conversion Service. Most of the degradation was caused by rill erosion – the impacts of raindrops on moving soil particles along with water. The US and Canada use intensive agriculture, and they have some of the highest soil erosion rates of the world. In many cases row crop agriculture (intensive agriculture) leaves the soil exposed. Any vegetation that is growing has the ability to absorb the impact of the raindrops or completely eliminate soil erosion. Some of the highest erosion rates in the world occur in the U.S. and Canada where row crops leave soil exposed
23PART 5:OTHER AGRICULTURAL RESOURCES WaterFertilizerEnergyPesticidesSoil isn't the only important agricultural resource. Water is probably the single largest additional factor in terms of agriculture. For instance in the state of Washington on the east side of the Cascades essentially all of the agriculture there with maybe the exception of ranching and dry land wheat, is dependent on irrigation. All of the apples and most of the truck crops in eastern Washington rely on water more than they rely on soil. The soil resource is abundant, but the availability of water is what limits productivity. There have been enormous federal projects associated with providing water to these lands. The Grand Coulee dam, for instance, pumps water to several million acres of agricultural land. As much as 80% of water withdrawn for irrigation never reaches intended destination. The cheap cost encourages over-use.The availability of nutrients is also a major agricultural limitation, and fertilizers are agricultural resources in limited supply. The price of fertilizers has consistently decreased with time. In their real cost they were highest when they were first introduced, and in terms of their real cost relative to agricultural productivity, they are about the cheapest they have ever been in history. Energy in particular to run machines and also to produce things like fertilizers and pesticides is also a major input into agriculture. Pesticides are poisons that are produced with a specific killing action in mind. Insecticides, for instance, kill insects and herbicides kill specific kinds of plants. The use of these resources has been very important in modern agriculture.Agriculture is the biggest global consumer of water, but there are many ways we can reduce water use (above - downward facing sprinklers deliver water more efficiently than upward-facing ones).
24FertilizerLack of nitrogen, potassium, and phosphorus often limits plant growth.Adding nutrients via fertilizer usually stimulates growth and increases crop yields.Average of 20 kg/ha fertilizer used.Average of 90 kg/ha fertilizer used.Manure and nitrogen-fixing bacteria are alternative methods of replenishing soil nutrients.The major soil elements needed by plants (macronutrients) are nitrogen, potassium, phosphorous, calcium, magnesium and sulfur. In areas of high rainfall amounts, calcium and magnesium are often leached out of the soil and must be replaced with lime. Nitrogen, potassium and phosphorous are more commonly limiting to plant growth, and a good deal of the increase in agricultural productivity in the last half of the 20th century was due to the addition of inorganic fertilizer containing these 3 elements. Over-fertilization can harm plants, lower productivity and (in particular with manure and phosphates and nitrates from feedlots and farm fields) can cause aquatic pollution. Nitrates in drinking water can even kill newborns. On the other hand in developing countries crop production could as much as triple with an increase in fertilizer use to the level of the world average.
25Pest ControlBiological pests reduce crop yields and spoil as much as half the crops harvested annually.Estimated up to half current crop yields might be lost in the absence of pesticides.Crops grown without synthetic fertilizers or pesticides tend to have lower yield, but have lower operating costs and less ecological damage.Up to 90% of all pesticides never reach target organisms (see Figure 7.19). In terms of inputs into agriculture one of the things that we see is that an excess of things like fertilizers and pesticides are utilized in order to provide an adequate amount to the plant. Precision agriculture is one of the exciting areas of agricultural research and study now. Rather than bathe a large area with say a pesticide, the pesticide can be targeted for where it is needed. The solutions to these problems are still probably off in the distant future.
26Up to 90% of all pesticides never reach target organisms. In terms of inputs into agriculture one of the things that we see is that an excess of things like fertilizers and pesticides are utilized in order to provide an adequate amount to the plant. Precision agriculture is one of the exciting areas of agricultural research and study now. Rather than bathe a large area with say a pesticide, the pesticide can be targeted for where it is needed. The solutions to this problem is still probably off in the distant future.
27PART 6: NEW CROPS & GENETIC ENGINEERING At least 3,000 species of plants have been used for food at some point in time, but most world food comes from 16 crops..Many new or unconventional varieties might be valuable food supplies.Winged-bean - can eat all parts and grows in new, warm habitatTriscale - drought resistant and grows in light, sandy, infertile soilSo far, the major improvements in farm production have come from technological advances and modification of a few well-known species.The green revolution refers to the global spread of new, high-yield varieties of plants. These varieties are "High responders" to optimum levels of fertilizer, water, pesticides, light, etc.Developing new crop types and changing the genes of plants and animals is absolutely not new. Until recently genes were altered in plants by recombining genetic material that was already present in a species. Recently, genetic engineering has been used to change characteristics of things such as to make a more flavorable tomato or engineer Bacillus thurengiensis toxin (a poison that kills only leaf-eating caterpillars) into a poplar tree. Such good traits of other species can be introduced into new species. Lately, more well known species have been genetically engineered and those situations where well-known species with a high potential for response have been used have been determining where and when money is spent and what crops are modified. Corn, tomatoes and (in the case of trees) poplars have been modified.
28Green Revolution "Miracle Crop" Yield One of the things that's been noted is that high responders (called "Miracle Crops") often exhibit their tremendous response only within a narrowly defined hospitable habitat (for instance fertility, water and temperature ranges needed are at optimal conditions). So, to get response requires a optimal habitat for the growth of the plant. For many traditional variety of crops can produce under a wider set of environmental circumstances. Thus, to get the optimal response of the high responders has required the input of more fertilizers, water, etc. This does not work well in non-technological situations where optimal habitat inputs cannot be provided.Most major improvements in farm production have come from technological advances and modification of a few well-known species. A stimulus for the Green Revolution is that corn yields jumped from 25 to over 100bushels per acre in the last century. Most of this gain in productivity was accomplished through conventional plant breeding techniques. There has also been a rise of dwarf varieties.
29Genetic EngineeringGenetic engineering is the splicing a gene from one organism into the chromosome of another.These Transgenic organisms are called Genetically Modified Organisms (GMOs) producedThese new genes result in plants with pest resistance, built in weed control and wider tolerancesOpponents fear traits could spread to wild varieties, and increased expense would largely hurt smaller farmers.As mentioned earlier, genetic engineering is actually introducing the genes from one species into another. In this case transgenic or genetically modified organisms (GMOs) are produced. These crops are becoming increasingly important. Right now about one-third of soy beans and corn are transgenic. 60% of all processed foods in NA contain transgenic products.Things typically introduced into the organisms are pest resistance and resistance to herbicide toxins (chemicals used to control weeds). The public does not really accept genetically modified organisms on a wide scale, and public opposition to GMOs is increasing. In some cases this opposition has been expressed in a violent form. For example the Earth Liberation Group recent fire bombed the offices, herbarium, library and some rare plant collections, but missed the target (GMOs). One of the reasons the University was attacked is because the universities are generally open areas where the dispersal of information is encouraged. The same group actually misidentified raspberries in an earlier episode and destroyed them thinking they were transgenic.
30Transgenic Crop Field Releases This slide shows the trend in transgenic crop field releases in the U.S. for the last 15 years. The development and utilization of transgenic crops has grown substantially in the last few years. It isn't necessarily required that a permit be obtained for doing this since in most cases these are considered to be relatively, non-significant events. For instance if you consider traditional methods to breed new varieties, then there are hundreds of thousands of new varieties already known to have been created. Something on the order of 7 or 8 new crop varieties or transgenic plants are grown and moved out of the lab each year.
31PART 7: SUSTAINABLE AGRICULTURE Sustainable agriculture (regenerative farming) - goal is to produce food and fiber on a sustainable basis and to repair damage caused by destructive practices. Soil is essential to sustainable agriculture.Soil conservation - land management, ground cover, climate, soil type and tillage system are important elements in soil conservation.One of the major questions we have about agriculture and its ability to produce food is whether or not it is sustainable in the long term. The concept here is to produce food and not have significant destructive agricultural practices destroy the soils ability to produce that food consistently into the future. Clearly, forever increasing food production is not possible. An infinitely increasing population will at some point outstrip our ability to produce food. Soil conservation is very dependent on maintaining ground cover, and ground cover, in turn, affects whether or not climates have moderate, gentle rainfall or wash topsoil away. Good land management policies result in habitats in which it is much easier to control erosion. For the remainder of this chapter we will consider the effect of land management, ground cover and tillage type on soil erosion and renewability. You should keep in mind that many things enter into making agriculture sustainable or not. Similarly, many factors are involved in determining whether soil can be conserved and replenished or not.
32Ways to Manage Topography Contour - Plowing and planting across (with the contour) slope to slow flow of water (left).Strip-farming - Planting different crops in alternating strips along land contours (left).Terracing - Shaping land to create level shelves of earth again with the slope to hold water and soil (see next slide).Planting perennial (plants that live >2 years) speciesAfter the dustbowls of the 1930's and the activities of the Soil Conservation Service (SCS), methods of managing topography and preventing and slowing soil erosion were developed. Particularly, contour plowing and strip farming (where vegetative areas are interspersed with crop areas) were introduced by the SCS and practiced extensively by farmers. These contour plowing and interspersing species were most effective when used in conjunction with terracing. A lot of these types of farming have been undone in the last decades because of the substitution of chemicals and herbicides, and because larger and larger equipment isnecessary for these practices to take place.
33Flooded terraces for growing rice in China Here are examples of terracing that can be an extremely efficient and sustainable ways of certain types of agriculture (in this case flooded rice agriculture). I previously mentioned the 1060's famine that occurred in China with the Great Leap Forward. In this case agricultural methods were applied that did not respond favorably to the land type. In many cases, terraces that had been in existent for hundreds (perhaps thousands) of years were plowed for the first time and destroyed. In many cases the seal for the flooded agriculture was a thin clay layer. Plowing destroyed this clay seal resulting in the terraces no longer holding water. You saw how the food situation in China crashed during the 1960's. Food productivity did not come back to pre-1960's levels until the terraces were re-established.
34Providing Ground Cover Keeping an area vegetative is probably the single most important factor in whether or not an area will be degraded in long-term sustainable agriculture. Bare soil, for instance, typically has soil erosion rates many times larger than that of areas continuously vegetated. Also, typically less water enters soil that is barren compared with vegetated soil. Water availability often does limit productivity in agriculture. So, systems that keep the soil vegetated for longer periods of time and systems that break the continuous de-vegetation of soil are very important in terms of renewable and sustainable agriculture.
35Providing Ground Cover and Reducing Tillage Cover does not have to be alive, and perhaps one of the greatest advances in terms of sustainable agriculture (a recent revolution in the U.S.) is what is called reduced tillage methods (minimum till, conserv-till and no-till). With these methods, the residue (dead vegetation) is left on the surface where it acts as mulch and as a source of nutrients. Rain drops hit on dead corn plants instead of the bare soil, thus minimizing erosion. With reduced tillage methods turning and disturbing the soil is considered to be a thing to minimize. Here, the methods reduce the energy input into the land associated with physical plowing. These methods rely on herbicide or some other method of killing the vegetation after crops are harvested. Herbicide application might increase the energy input, but in all cases reduced tillage tends to decrease the amount of soil erosion. In theory, at least, this is much more sustainable agriculture.Annual row crops cause highest rates of erosion because they leave soil bare for much of the year. When crop residues are left in fields they cover the soil surface and break the erosive effects of wind and water. Surface plant residues also reduce evaporation and moderate soil temperatures thus protecting soil organisms as well as aerating and rebuilding the soil organic matter. Again we note that plant residue can increase water infiltration and reduce runoff thereby reducing erosion.
36Methods Used to Reduce Bare Ground Erosion Providing Ground CoverLeave crop residue after harvest.Plant cover crops after harvest.Add protective ground cover such as manure, wood chips, straw, leaves, etc. (mulch).Reduced TillageMinimum Till - Chisel plow or ridge-tillingConserv-Till - Coulter (Disc)No-Till - DrillingOften farmers using conservation tillage must depend relatively heavily on pesticides.Cover crops can be planted immediately after harvest in order to hold and protect the soil. Some cover crops (e.g., alfalfa and clover) fix nitrogen in the soil and can then be harvested as high quality hay. We've all probably at one time added protective mulch. Here in Seattle, mulch can prevent erosion and also insulate plants that have their buds underground in the winter. Mulching can cause and imbalance in carbon to nitrogen ratios resulting in soil microorganisms immobilizing nutrients.In the 18th century management of crops involved using a moldboard plow to dig a deep trench and turn the topsoil upside down. This traditional tillage increased crops by helping to control weeds and pests (reducing competition), by bringing nutrients to the surface and improving surface drainage and aeration. Today, we know that for many crops less plowing and cultivation can improve water management, preserve soil, save energy and increase yields.We will consider 3 methods that are currently used to reduce tillage. Conceptually, minimum till is simply reducing the number of times the soil is disturbed. Typically, a curved chisel-like blade is used to turn over the soil and in the process forms ridges upon which seeds are planted. This method leaves 75% of the plant debris on the soil surface between the ridges. Conserv-till uses a sharp, pizza cutter-like disc called a Coulter that opens a furrow just wide enough for a seed to be inserted. This results in very little soil disruption and leaves most plant debris on the surface. With no-till planting seeds are drilled directly through mulch and ground cover. With this method a cover crop can be interseeded with a subsequent crop.The dilemma of requiring on more pesticides and herbicides with reduced tillage procedures is not a foregone conclusion. Integrated Pest Management (IPM) is a general way of acknowledging pest control methods that combine crop rotation, trap crops, natural repellents and biological controls with reduced tillage practices, thus circumventing the heavy dependence on chemicals.
37Cocoa pods (left) are growing directly on branches of a shade-tolerant tree native to warm, moist lowland forests of the tropics. In contrast, coffee is native to cool, mountain forests of the tropics.Vanilla, bananas, cocoa and coffee are food products grown in developing countries and mostly consumed in wealthy countries. Coffee and cocoa are small understory trees that grow in shade. With the green revolution, as you might expect, genetic varieties of these shade trees were developed that grow in full sun where more light energy translates into higher yields. In contrast, shade grown trees are healthier, require less fertilizer and water and support larger and more diverse populations of native birds and use less unfair labor practices such as child slave labor. More than half of the world's biodiversity hotspots occur in coffee and cocoa growing regions. The Bahia area is in Brazil's Atlantic forest where biodiversity reigns supreme in the remaining 8% of the original forest left. Hope on preserving this area lies with consumers being willing to pay small premiums for organic, fair-trade, shade-grown chocolate and coffee. In local Seattle coffee shops sustainable coffee can be found under brands such as "fair-trade blend" and "commitment to origins." You can simply ask a barista to direct you to an environmentally sound purchase. A responsible consumer will also read the labels. Sustainable agricultural farmers usually will advertise their methods.
38Organic and Locally Grown Foods I wouldn't be in the Northwest if I didn't mention the desire of people for organically and locally grown foods as part of sustainable agriculture. We've come to expect that we can buy a tomato at anytime of the year here. Seasonally of crops is no longer an issue, although prices still vary by season. The American consumer has come to expect to buy anything, anytime, anywhere in the US. There is a lot to be said for utilizing food sources that are more locally available and also for utilizing food sources that are produced in such a way that they don't use large amounts of synthetic fertilizers and pesticides. That being said, the concept of organic farming as a label is a little silly, especially given the fact that plants are organic (carbon based) in nature regardless. Synthetic things are allowed in organic farming, while many natural things aren't. In many cases we are allowed to mine nutrients from the earth and ground them up to a fine powder, but we are not allowed to treat them with acid to make them more available. We are allowed to use synthetic hormones to trap insects into a sticky trap, but we are not allowed to use pesticides; so, I have not really thought much of the organic faming label except from the perspective that it typically produces a food with less pesticides in it and relies more on the utilization of organic materials and waste material rather the synthetic nutrients.
39Note the contrast in how the farmers tend their fields in these two pictures. Top picture is a farmer in a small field of a developing country using a moldboard plow to turn over the soil to "renew" the nutrients, improve drainage and aeration. Below is a setting for large, high energy, chemical corporate farm. After completing this chapter you can now contrast these 2 approaches to sustainable farming. This ends the consideration of agriculture and world food production of Chapter 7.