SAFS FINAL
Feed conversion ratio
kg feed consumed per kg of animal product produced. This is a way to measure the efficiency of production.
Cucurbitaceae (cucurbits)
melon, cucumber, squash, pumpkin
Asteraceae:
lettuce, artichoke
Alliums
onion, garlic, leek, chive
List at least three functions that soils perform in agriculture.
-Anchors plants -Serves as reservoir for nutrients -Allows for air and water exchange (between plant and environment)
Are hormones and antibiotics used in livestock production? Explain.
-Some hormones are used in livestock production beef, lamb, and dairy cattle production. -None are approved for poultry or hogs. Antibiotics can be used two ways in livestock production: clinically (to control diseases) and non-clinically (to improve growth). When they are used, withdrawal periods must be followed before meat and milk enter the food supply. Antibiotics are routinely tested in milk and meat, to ensure that levels are below legal limits, or tolerances.
According to Smith Spangler are there differences between organic and conventional farming
-risk of detecting any pesticide residues in fruits, vegetables & grains organic foods tend to have lower risk -risk of detecting E coli in fruits, vegetables & grains there is no difference -risk of detecting other enteric pathogens in meat and egg products there is no difference -risk of detecting antibiotic-resistant bacteria in meats there is no difference -risk of detecting naturally occurring mycotoxins such as DON and OTA organic foods appear to have a slightly lower risk for DON, but no difference for ochratoxin A -risk of detecting heavy metals like Cd, Pb, As and others there is no difference
In your garden, you see a large green caterpillar feeding on your broccoli. You look more closely and see what looks like a little black wasp on top of the caterpillar. What do you think might be going on? Assuming you like broccoli (!), is this something you want to encourage in your garden?
A reasonable guess is that the little black wasp is a parasitoid. It's likely that she is laying her eggs in the caterpillar, and that when they hatch, the caterpillar will be doomed (consumed from the inside out). Since the caterpillar is eating your beloved broccoli, you definitely want to encourage this parasitoid to lay a lot of eggs!
When was the Organic Food Production Act passed? When were the National Standards first implemented?
1990, 2002
What are the recent trends in production and consumption of animal products (meat and milk) worldwide?
30% of the ice-free land worldwide is used for livestock production systems, and this makes up nearly 80% of our agricultural land. Worldwide, livestock production AND consumption has increased dramatically in the last 30-60 years. We see more dramatic increases in the developing world than in developed countries. Livestock production has also become more efficient, with carcass weight for meat animals like pigs, cattle, and chickens increasing steadily during this time.
What is a "green manure" cover crop? What characteristics should a good green manure crop have?
A green manure crop is one that is grown for the purpose of incorporating it into the soil to increase the soil organic matter. It is being used as a soil amendment. A good green manure crop would have a lot of biomass (e.g be a BIG plant), fix nitrogen (e.g. be a legume), and would grow quickly to suppress weeds.
What is a pathogen, and what are the three major classes of plant pathogens? A pathogen is a disease-causing living organism.
A pathogen is a disease-causing living organism. Fungi, bacteria, viruses
What are some different ways we can learn about a soil's physical, chemical or biological characteristics?
A penetrometer tells us how compacted a soil is. Texture analysis (in the lab, or by feel) A standard chemical soil test run by a lab (to determine plant-available nutrients, organic matter content, and CEC). Various tests of aggregate stability tell us whether or not there is favorable secondary structure (or aggregation) of soil particles. We can evaluate the elements found in plant tissues that are being grown in the soil; this gives us an indication of whether soils have sufficient plant nutrients. Different assays for soil biological activity (like the Solvita test, or bioassays) give an indication of how much microbial activity is present in the soil.
What is hydroponic agriculture, and what are some advantages and disadvantages of this system of growing?
A system of growing plants in a nutrient solution with or without the use of an artificial medium like sand, gravel, rockwool, etc. -Advantages: very high yields off-season production is possible efficient use of resources (fertilizers, water, land) suitable for mechanization can avoid some problems associated with soil: drainage, salinity, diseases -Disadvantages: involves expensive infrastructure usually involves high energy costs relies upon synthetic fertilizers and mechanization
focusing on the paper by Smith-Spangler et al (2012), are organic foods more nutritious than conventional foods?
Across the many studies evaluating several types of nutrients, only two nutrients were significantly higher in organic than conventional produce: phosphorus and total phenols. The many others evaluated (vitamin A, vitamin C,.
What is the difference between annual, biennial, and perennial crop plants?
Annual plants germinate, grow, flower, and reproduce once in a single year. Biennial plants take two years to accomplish this same life cycle. Perennials live and reproduce again and again over many years.
List and describe at least five factors that affect the nutrient content of fruits and vegetables.
BEFORE harvest, how food is produced can affect nutrient content: Variety choice. Some varieties have much higher levels of vitamins and minerals than others. Soil nutrient status. Chronically depleted soils can produce crops with lower levels of certain minerals than very fertile soils. Similarly, produce grown in soils with very high levels of certain minerals may have higher levels of those minerals. Maturity at harvest. Nutrient content changes as the plant goes through its' life cycle; harvesting too early or too late can result in a less nutritious product. Diet. Ruminant livestock (cows, sheep, etc.) that are fed grass (as opposed to grain) produce higher levels of Conjugated Linoleic Acids, which have antioxidant activity. Stresses to the plant. Many secondary metabolites produced by the plant have antioxidant activity, and these are produced in higher amounts when plants are exposed to various stresses (UV light, drought, etc.). -AFTER harvest, how you handle your fruits & vegetables can impact nutrient content: Freshness and storage conditions. While minerals are quite stable, Vitamins like A and C are quite unstable when exposed to heat, light, and oxygen.
Why is biodiversity useful in an agricultural ecosystem?
Biodiversity in an ecosystem makes that ecosystem better able to cope with change - the existing resources in the ecosystem are used more efficiently, more ecosystem functions and niches are being filled, and the ecosystem is more resilient to disturbances (physical, biological, environmental, chemical, etc.)
What is Cation Exchange Capacity (CEC) of a soil? Is it better to have soil with a high or a low CEC?
CEC refers to the ability of a soil to adsorb (or hold onto) cations in the soil. Cations are positively charged ions. Many plant nutrients, such as Calcium (Ca), Potassium (K), Magnesium (Mg), and ammonium (NH4), are present in the soil as cations. A high CEC is better because it means more ability to hold onto nutrients.
What is the difference between a cash crop and a cover crop? What are some reasons that a farmer might choose to plant a cover crop? Are there any drawbacks to cover cropping?
Cash crops are planted in order to be harvested (grains, vegetables, fruits, hay, etc), whereas cover crops are planted for other purposes, primarily to build the soil. Reasons to plant cover crops are primarily to prevent soil erosion, to "catch" nutrients and prevent leaching, and to build soil fertility - but they can also be used for other purposes such as biofumigation. Drawbacks are that cover cropping adds expense (seeds, management time), and that when cover cropping, the land cannot be used for cash crops. If not managed properly (tilled before setting seeds), the cover crop can become a weed or can increase weed problems.
What is meant by 'classical biological control'? Give at least two advantages and two disadvantages of this approach to controlling insects.
Classical biological control is normally used when you have an introduced pest - ie one that is not native to the area in which it's causing a problem. Biological control involves searching for a natural predator in the area where the pest originated, and releasing this predator to control the pest in the new area. Advantages: Self-sustaining and permanent if successful because the predator-prey relationship will keep both populations in check, Not expensive for farmers, Environmentally friendly because it's a chemical-free approach. Disadvantages: It might not work because the organism might not thrive in this environment, It takes a very long time, Introducing an organism might have unintended consequences
What is compost?
Compost is a biologically stable material that results from decomposition of organic residues
when building a compost pile, why would someone need to know the carbon to nitrogen (C:N) ratio of the starting materials?
Composting (especially hot composting) relies on thermophilic (heat-loving) bacteria. Bacteria require their "diet" to be roughly 25-30:1 C:N. If there is excess Carbon, the bacteria will not be able to completely break down the raw ingredients. If there is excess Nitrogen, the excess Nitrogen will be volatilized and released as ammonia (leading to a stinky compost pile).
Why would a farmer decide to compost her manure before she used it in her garden? Is there any drawbacks to doing this?
Composting kills plant pathogens, animal pathogens, and weed seeds that are found in manures. The farmer could use composted manure right away on her organic garden without worrying about food safety issues that could be a problem with raw manure. Composting also reduces odor and improves the texture of the manure. HOWEVER, drawbacks are that much of the nitrogen found in manure is lost during composting, and the process of composting can be quite time-consuming.
Cons of reduced tillage system
Cons: -Need specialized equipment (like no till seeders or transplanters) -Usually need herbicide (because it is important to kill weeds that will compete with the crop) -These systems are vulnerable to compaction because of heavy equipment driving on them, without loosening the soil with intermittent deep tillage. -It is hard to add fertilizers and amendments to these systems -The presence of cover crop residue on the soil surface cools the soil, which can be a disadvantage in cool climates.
at least two well-founded reasons why there might be no difference between organically grown crops might and their conventionally grown counterparts
Conventional and organic farms BOTH are careful to provide enough nutrients in fertilizers to meet crop needs, and healthy crops contain balanced amounts of macro and micro-nutrients they need. - Things like crop variety, weather, and freshness are likely to impact nutrient levels as much as more than the source of plant nutrients/type of fertilizer.
Crop rotation provides some of the benefits of a polyculture system as well as some of the benefits of a monoculture system. Explain what crop rotation is, and list at least 3 reasons that crop rotation is a good idea.
Crop rotation is a planned system of growing different crops in succession on the same piece of land. Rotation provides some of the benefits of polycultures: increased biodiversity, yield stability and more efficient and complete use of resources, but usually only over time - not within a growing season. (Note - It doesn't give much protection against crop failure within a given year!). Within a growing season, a crop in rotation can be grown as a monoculture. The primary benefit is ease of management because of uniform crop needs, harvest time, and growth habit.
What three federal agencies are involved in regulating transgenic crops, from their development to their commercialization?
EPA - environmental protection agency USDA - US department of agriculture FDA - food and drug administration
Can you give any examples where we have very little genetic diversity within mainstream agriculture?
Examples of limited diversity that we mentioned in class included: corn, banana and wheat... though the same is true for many other food crops and livestock species.
If we think of the soil as a pool of available nutrients for plant growth, what are the processes by which we add nutrients to, and subtract nutrients from, the pool?
Gains: fertilizers, nutrient fixation, microbial decomposition, weathering Losses: plant uptake, volatilization, erosion, nutrient fixation, and leaching
Explain the difference between an overlap planting of two crops and planting a mixture of the same two crops. What are the advantages of each?
In an overlap planting, the two crops would overlap for some part of their life cycles. In a mixture, the two crops would be planted together, and would overlap for their entire life cycles. Mixtures increase crop biodiversity throughout the entire growing season, conserve water and nutrient resources. The two crops might complement one another (increasing total production season or increasing total yields), or might be antagonistic or compete for resources. Overlap planting minimizes some of the competition that can occur in mixtures, and therefore often provides better yields.
What are some of the ways that genetic engineering has been used in commercial crops?
Genetic modification is a way to add traits that aren't available in that plant already. The most common traits are herbicide tolerance, insect resistance, and virus resistance. The very first GE crop was the Flavr Savr tomato, which ripened more slowly than normal tomatoes. And 'golden rice' contains genes that make vitamin A, which is not normally found in rice.
Define gravitropism and phototropism
Gravitropism - the process by which plant roots grow in the direction of gravitational forces, and plant shoots grow in the opposite direction. Phototropism - the process by which plants grow towards light.
How could the use of transgenic crops negatively impact farmers (organic or conventional) that are not growing them?
If their neighbor is growing them, pollen could move onto their crop. If they are selling their crop as organic and a buyer decides to test it for the presence of the transgene, they may detect the small quantities of the transgene and they may refuse to purchase the crop. If they are saving seeds, they may end up with the transgene in their saved seeds. In the case of Bt crops, they could speed up the development of Bt-resistant caterpillars, making that biological insecticide not so useful for organic growers.
What rules do certified organic farmers have to follow if they use 'raw' animal manures? What's the reasoning behind these rules?
If they use raw manure, they can only use it on non-edible or perennial crops, or at least 60 days before harvest on edible crops like vegetables. Composted manure can be used at any time. They also have to provide a plan for how they will apply and use manure in a way that doesn't contaminate waters with bacteria or nitrates.
Define 'integrated pest management'.
Integrated pest management is the use of different techniques in combination to manage pests, with an emphasis on methods that are least harmful to the environment and most specific to the particular pest. TO do this, growers need to understand how each pest works; e.g. it's life cycle and how/when/where it causes damage.
How does 'finished' compost different from the feedstocks (aka the starting materials)?
It's already decomposed, nutrients are in a more stable (and less available) form, pathogens & weed seeds are killed, it has a finer texture, and smells and weighs less.
Are crop farms, livestock farms, or integrated (crop plus livestock) farms more likely to end up accumulating nutrients because nutrient IMPORTS exceed nutrient EXPORTS?
Livestock farms tend to accumulate nutrients because a large amount of nutrients end up staying on the farm as manure. Crop farmer tend to have a nutrient deficit because most nutrients are exported off the farm as crops. Integrated farms are more likely to be able to balance nutrient inputs and output.
What are some ways that farmers promote or limit biodiversity on their farm?
Limit biodiversity: monocultures (low levels of "planned biodiversity") frequent disruption of habitats broad-spectrum pesticides Promote biodiversity: Varied land use near fields (hedgerows, woodlands etc) Beneficial insectaries Use organic sources of nutrients that require microbes to break them down Plant many types of crops
What are macronutrients? How do they differ from micronutrients? Name the three primary macronutrients.
Macronutrients and micronutrients are both required for plant growth, but macronutrients are needed in large quantities by the plant. The primary macronutrients are: Nitrogen, Potassium and Phosphorus. Micronutrients include: boron, chlorine, copper, iron, manganese, molybdenum, zinc and nickel. Some (but not all plants) require cobalt, silicon, sodium and selenium.
Give at least two well-founded reasons why organically grown crops might be MORE nutritious than their conventionally grown counterparts
More attention might be paid to building soil nutrient levels; higher soil nutrient levels might be taken up into crops. - In organic dairy and meat production, ruminant animals are required to have a portion of their diet met by grazing on grasses (which would increase CLA levels). This is not a requirement for conventional systems. - Organically grown crops may experiences more stresses, and therefor may produce more defense-related compounds which have antioxidant effects.
Where in the soil profile are most of the soil biota found?
Most are found in the top 10-15 cm of soil, or the top 4-6 inches.
For some crop plants, it is important that the plant enter the reproductive phase of development. For others, it is actually undesirable for the plant to enter the reproductive phase. List at least ten crops that fall into each category. Hint: Think about which plant organs are harvested and consumed, and whether they are a vegetative or a reproductive organ...
Need reproduction (& pollination): tomato, pepper, melon, cucumber, apple & other pome fruits, cherry & other stone fruits, bean, pea, wheat, rice, oats, corn, sesame, safflower, nut crops, millet, etc. (anything where seeds or fruits are harvested) Reproduction is undesirable: lettuce, cabbage, celery, potato, carrot, kale, beet, leek, arugula, rhubarb, onion, etc. (any crops where roots, stems, or leaves are harvested)
In the U.S., are foods that contain GE crops labeled? Why or why not?
No - they are not labeled. Some foods are labeled as GE-free or GMO-free. This is because it is FDA policy that they do not require a special label advertising the presence of what they call "incidental additives", items that are present at insignificant levels and that have no technical or functional effect on the food. Transgenes and the proteins they produce are present at insignificant (in some cases nonexistent) levels in the final food product, and have no measurable effect on the final food product, thus they are not labeled.
Does the development of Roundup-resistant weeds have a negative impact on organic growers?
Not really. Organic growers do not use the herbicide glyphosate (Roundup), so tolerance to that herbicide will not affect them.
The 'Certified Organic' label has been described as focusing on the process rather than the product. Briefly explain what that means.
Organic certification focuses on the processes that farmers and food manufacturers use to grow and produce foods, rather than on specific qualities of the foods themselves. Foods aren't tested for any particular attribute - such as absence of pesticide residues, traces of genes from GM crops, or microbial contamination. The label simply tells the consumer something about the practices used to produce the food.
what is the difference between organic and sustainable agriculture?
Organic is a federally regulated term that means something very specific. One can be certified organic in the short term. Sustainable agriculture is one that can continue indefinitely while remaining productive. Most agree that it entails several dimensions: economic, environmental and social viability. Sustainability is hard (if not impossible) to demonstrate in the short term, but it is something one can strive for.
Plants and several soil organisms are considered primary producers, or photoautotrophic. Explain what this means, and where these organisms fit in the food web.
Photoautotrophic organisms are ones that photosynthesize, or use solar energy (plus water and carbon dioxide) to create carbohydrates. Because these organisms don't feed on other organisms, they are the foundation of the food web; all other organisms ultimately depend on them (or upon things that feed on them) as food.
What does the plant do with the glucose that is produced during photosynthesis?
Plants use some of the glucose that is produced to fuel cellular processes. It is used during cellular respiration. During respiration, in the presence of Oxygen, Glucose is broken down into carbon dioxide and water, releasing energy in the form of ATP.
Define polyculture. List the advantages and disadvantages of polyculture, as compared with monoculture.
Polyculture = the cultivation of more than one crop species on the same piece of land in various temporal and spatial patterns (over time and space) Advantages: slows spread of pests, more stable yield, insurance against crop failure of one crop, resources in the ecosystem are used more efficiently Disadvantages: complicated agronomic management, more host species may mean more pests and diseases at any one time.
Farmers and gardeners usually till soil to prepare it before planting. What are the pros and cons of doing this?
Pros: - makes the soil fluffy and soft, good for planting and seed germinating - incorporates organic matter into the topsoil Cons: Can result in compaction of the soil (especially if done when soil is wet), and the creating of 'plow pans'. Crop roots don't grow well in compacted soil. Tillage can break down soil structure at the soil surface, leading to crusting and erosion.
The soil bacterium Rhizobium is a very important soil microorganism in agricultural soils. What does it do, and why is it so important?
Rhizobium is a soil bacterium that infects the roots of Legume plants in a symbiotic relationship. Infected roots make nodules around the bacteria. Within the nodules, the bacteria convert atmospheric nitrogen (N2 gas) into nitrate that the plants can use, and they use as food the carbohydrates produced by plants. Without Rhizobium, legume plants would not fix nitrogen.
What is a Roundup-Ready crop? How does it work?
Roundup is one brand name of the herbicide glyphosate. Glyphosate kills all plants because it interferes with the functioning of a necessary protein, EPSP synthase. Roundup-ready crops have been genetically engineered to contain a modified version of the EPSP synthase gene (from a bacterium). Glyphosate doesn't target this modified gene, so glyphosate applications do not kill Roundup Ready plants. Roundup sprayed directly on the crop will kill all weeds and not harm the crop.
Examples of ruminants animals vs. non-ruminant
Ruminants include: cattle, goats, sheep, buffalo, camels, llamas, reindeer, deer and yak. Non-ruminants include: poultry, pigs, rabbits, horses and humans.
What are the three fundamental soil particles, and what is the key feature that differentiates them?
Sand, silt, and clay. The major difference is particle size! Particles of sand are larger than those of silt, which are larger than those of clay.
Define "season extension", and give some examples of season extension strategies used in agriculture.
Season extension refers to various methods of increase the functional length of the growing season, and it is widely used in cold climates like ours, where light and temperature limit crop growth during much of the year. Specific examples: greenhouses, low tunnels, transplants, rowcovers, or black plastic mulch to warm the soil postharvest storage of some crops plant and animal breeding to increase the harvest season associated with those products (we talked about examples with chickens, raspberry, and strawberry).
What is sewage sludge, and why is its use as an agricultural amendment considered controversial (and not allowed in organic systems)?
Sewage sludge is the untreated residue that's left over after processing human waste in a sewage treatment facility. While it is normally processed to kill any human pathogens, sewage sludge contains all of the things that go down household and industrial sewage systems. This includes some items that can be concentrated if applied to agricultural lands: pharmaceuticals, heavy metals, radionuclides (radioisotopes), etc.
What is soil texture? What is the difference between soil texture and soil structure?
Soil texture is an innate property of a soil, that cannot be changed by human activity. Soil structure refers to the arrangement of the fundamental soil particles into larger units, and is affected by mechanical and biological activities in the soil. Crop production practices affect these!
Why are microbes an important part of the nitrogen cycle? List at least three functions microbes perform in the nitrogen cycle.
Some microbes mineralize N (convert it from organic to inorganic forms) as they decompose organisms, by ammonification and nitrification. Some microbes fix N (convert it from N2 gas to inorganic nitrogen). As microbes use N themselves, they immobilize N (convert in into an organic form).
Define the following terms, which describe interactions between organisms in an ecosystem: symbiosis or mutualism, competition, antagonism, and parasitism.
Symbiosis/Mutualism - a mutually beneficial relationship Competition - demand by at least 2 organisms for limited resources Antagonism - Inhibition of or interference of a substance or organism by another Parasitism - one organism receives benefits from another by directly causing damage
Define and explain TMR, Rotational Intensive grazing, and Feed Conversion Ratio.
TMR - Total Mixed Ration - mixture of forages, grains, proteins, vitamins and minerals that provide complete diet to livestock. This is often used in dairy and beef cattle production, and allows producers to refine diets to meet specific needs of animals at a given time.
What is the Aquadvantage salmon? What precautions have the developers proposed to prevent environmental impacts from their production?
The Aquadvantage salmon is a genetically engineered Atlantic salmon that contains a growth hormone gene from Chinook salmon, with its expression controlled by an Ocean pout promoter. It shows a much faster growth rate than Atlantic salmon. To reduce the likelihood that the GE salmon will escape, survive, disperse, reproduce, and establish - and then have potentially negative effects on the U.S. environment - several precautions have been proposed. 1) The salmon are all-female, triploid and sterile, 2) eggs are produced in one site, and then shipped to a freshwater physically-contained site for production, 3) both of these proposed production stages are outside of the U.S. - there may be others, as well.
what is the food system
The food system encompasses all food production and consumption; farming, food processing, distribution, marketing, retailing and consumption.
If you had a choice between a two-year rotation (lettuce-tomato-lettuce-tomato) and a four-year rotation (lettuce-tomato-bean-onion), which would you choose and why?
The four-year rotation is better, for several reasons: -more time between similar crops, better chance of avoiding disease problems -less soil depletion because different crops place different demands on the soil -more crops are grown, so more biodiversity - the second rotation includes a legume in the mix, which is helpful for reducing N needs Lastly, if you look at the example in class of the Morrill plots, there is a chance that a rotation with more crops will slow down loss of organic matter from the soil.
What is the difference between the pesticide Bt and a transgenic Bt crop?
The pesticide with the active ingredient Bt is sprayed on crops. It is considered a natural biological insecticide, so it is permitted for organic growers to use, and many growers do use it. Transgenic Bt crops are crops that contain the gene from the Bacillus thuringiensis bacterium and therefore produce the Bt toxin in each plant cell. It is considered a "biopesticidal plant" because it produces the Bt pesticide all on its own. Because Genetic Engineering is a prohibited technology for organic growers (it is synthetic); Bt crops would not be permitted for use.
Growers that plant transgenic Bt crops are required to meet a 'refuge requirement'. What does this mean, and how does it work?
The refuge requirement means that growers must plant a certain percentage (originally it was 20%, it now varies) of non-Bt crops around their Bt crops. The idea is that Bt-tolerant insects will develop within the Bt crop. The non-Bt crops are a refuge where Bt-susceptible insects can hangout and then will be around to mate with the tolerant insects - slowing down the development of Bt-immune insect populations.
You take a soil sample that doesn't have any stones or large particulate matter. You give the sample to your favorite soil lab. They tell you that 30% of the sample consisted of particles that were too large to pass through a 0.5 mm sieve, and that, based on their testing methods, 40% of the original sample was silt. What is the texture of your sample? (Hint: refer to the soil texture triangle)
The sample is 30% sand, 40% silt and 30% clay. Using the soil texture triangle, this is a clay loam.
The 'plant disease triangle' concept is used to describe how much potential exists for a major disease problem. Explain this idea. Using this concept, describe three basic strategies to reduce the likelihood of a plant disease outbreak.
The three sides of the plant disease triangle are 1) the pathogen, 2) the environment, and 3) the plant. For diseases to take off, you need to have the pathogen present, to have environmental conditions that are conducive to the pathogen, and lastly, you need to have a susceptible host plant. To prevent diseases, you can try to reduce all of these - eliminate the pathogen by using good sanitation, make the environment unfavorable for pathogens (minimizing humidity is one way to do this), and lastly, remove susceptible hosts - by using crop rotation.
Why is it important to incorporate (till in) raw manure after spreading it (applying it to the field)? Give at least three reasons.
To avoid loss of nutrients due to volatilization and leaching, to avoid contamination of surface waters with nitrates and bacteria, to make sure that it's where the plants need it and can access it, maybe to reduce odors...
What does it mean to 'turn' a compost pile, and why is it necessary?
Turning just means mixing the pile up. It is necessary because the bacteria need oxygen as well as the carbon and nitrogen found in the raw starting materials. Turning evenly distributes the oxygen found on the outside of the pile and the heat that builds up on the inside of the pile - both oxygen and heat are needed for effective decomposition.
For each of the following compost 'feedstocks', indicate whether it has a C:N ratio that is much lower than 30:1, or much higher than 30:1.
Vegetable wastes - lower Straw - higher Fresh chicken manure - lower Fresh pig manure - lower Sawdust - higher Corn stalks - higher Grass clippings - lower Paper - higher
In human nutrition, aside from water, there are five major classes of nutrients in food; what are they?
Vitamins, Minerals, Carbohydrates, Proteins, Fats
who was justis von liebig and what was his discovery towards agriculture?
Von Liebig discovered that there are 16 essential elements for plant growth (19 if you count Nickel, Silicon, and Sodium, which are not considered essential by most researchers). His discovery led to the development of fertilizers that added only the specific nutrients that were needed for plant growth, also know at the time of their development as "synthetic manures".
There are two primary types of vascular tissue in plants. What are they, and what functions do they serve?
Xylem - water and nutrients are transported from the roots to the rest of the plant. Phloem - the carbohydrates produced during photosynthesis are transported from source (the photosynthetic leaves) to sink (any part of the plant that needs energy).
Rotational intensive grazing (AKA mob grazing)
a strategy of feeding pasture where herds are regularly moved to new pasture that has NOT been grazed recently. This allows the pasture to regrow and have optimum feed quality when it is grazed, and it also prevents undesirable species from taking over. One disadvantage of this system is that it can be very labor intensive.
How would you describe a soil that is "healthy" from a biological, physical, and chemical perspective?
abundant and diverse living organisms (biologically healthy) plenty of nutrients required by plants (chemically healthy) well-aerated with plenty of pores (physically healthy)
What do the organic regulations say about livestock production?
all livestock must have access to the outdoors. All feeds must be certified organic. For ruminants: must graze during the pasture season (at least 120 days), and get at least 30% dry matter from pasture during this time. -finish feeding period (for meat animals) where grain is fed to maximize meat quality cannot exceed 120 days. - antibiotics generally cannot be used, except in special circumstances with a lot of restrictions - producers must NOT withhold treatment to preserve organic status of animals
Rosaceae
apple strawberry pear peach brambles
Leguminosae
bean peas lentil soybean
Brassicaceae (crucifers):
broccoli, cabbage, cauliflower, kale
Graminae (grasses):
corn sugarcane wheat oat rice
What happens to pesticide residues on materials that are composted?
depending on which pesticide you are talking about. Some pesticides are mineralized to produce inorganic compounds. Others are partially degraded to form secondary compounds. Some are bound tightly to (or complexed with) humus particles. Yet others are lost, through volatilization, leaching, etc. A few (such as the aminopyralid example we discussed) don't break down quickly and are concentrated during composting because they are persistent in the environment.
Umbelliferae
dill carrot celery cilantro
List at least 3 valid concerns about the widespread use of transgenic crops. For each, give an example of a GE crop that might post a significant risk.
enhanced (or unexpected) allergenicity. Ex) soy, corn, or other food crop engineered to contain genes from tree nuts, peanuts, or other foods for which allergies are quite common - risks to non-target organisms. Ex) biopesticidal crops such as Bt corn - environmental effects. Eg) herbicide tolerant crops (what are the effects of using higher levels of a relatively non-toxic herbicide)
Eisler suggests several ways that we could enhance the sustainability of our livestock production systems worldwide. Give some examples.
feed less human food to livestock, focus instead on waste products (such as leftovers from food processing like sugar beets, orange juice), multi-use plants (for example, plants that produce human food and the rest of the plant can be used for livestock feed), and pasture. - raise regionally appropriate animals (breeds adapted to the diet, stress, and management conditions they will face in a particular area) - track energy use in livestock systems we can capture as much of it as possible - keep animals healthy (reduce stress in livestock raising systems so that we get fewer losses and can reduce antibiotic use) - eat quality, not quantity - the US per capita consumption of meat is among the highest in the world, Eisler argues that we (and the planet) would be better served by eating less meat (reducing demand) that is produced in more sustainable ways.
Lu et al study about if feeding children a diet of all-organic foods completely eliminate their exposure to pesticides
organophosphates(OPs) & pyrethroids. They demonstrated that switching to an organic diet greatly reduced the presence of OPs in children's urine samples, but that it didn't affect the presence of pyrethroids (which are present in lots of insecticides commonly used in households). Therefore, eating organic foods would likely reduce exposure to SOME pesticides, but not others.
Solanaceae
potato tomato pepper
What are ruminant animals? List at least three species of ruminant animals.
they have four-chambered stomach, which allows them to utilize energy from cellulose by breaking it down via microbial fermentation in the rumen. This enables them to consume high-fiber foods that non-ruminants cannot, such as grasses and forages.
What are some key practices that are part of integrated pest management?
think amurp - avoiding conditions that favor pests/diseases - using cultural methods to control pests - monitoring regularly for pests - relying on natural enemies to control pests - use pesticides as a last resort (and try to use the most specific pesticide possible).
The terms "organic by neglect", and "high-input organic agriculture" both refer to specific types of organic farming operations. Describe what is meant by each of these.
"organic by neglect" refers to the idea of avoiding all inputs, including pesticides - but also avoiding sound agricultural practices including good crop and soil stewardship. While this could be considered more "natural" than standard agricultural practices, it does not represent the organic farming principles promoted by the proponents of organic or sustainable agriculture. "high-input organic agriculture", sometimes called "organic by substitution" refers to the adoption of certified organic practices in combination with standard conventional practices, which include purchasing most inputs from sources far from the farm.
What are some of the reasons that we have relatively narrow genetic diversity represented in the crops and livestock that are grown commercially today?
- Consolidation in the plant breeding and seed supplying industries - Uniform agricultural production systems (therefore needing less genetic variation in crops). - Large scale distribution of crops (favors uniformity of crops)
What are some examples of cultural pest and disease management techniques?
-crop rotation - sanitation of planting materials - barriers; e.g. fences, rowcovers. - trap crops - using deterrents to pests - physical removal of pests
List and describe at least four things that you would learn about your soil from a standard soil test.
-pH - tells you whether soil is alkaline (basic) or acidic. Plants grow best, because nutrients are most available to them, at a neutral pH. -CEC - Cation Exchange Capacity indicates the soil's capacity to hold onto nutrients. In general, higher CEC values are better. -Organic Matter - This is the percentage of the soil that is made up of living, decomposing, or already decomposed organic material. Higher levels of organic matter mean more nutrients available to plants, and organic matter positively affects soil structure (see question 1). In general, higher values are better. -Macronutrients - with the exception of Nitrogen, the soil test tells you the level of many plant-available macronutrients (Mg, Ca, K, P). -Texture - we didn't talk about this specifically, but some soil tests will tell you the texture class of your soil.
What is a disorder (as compared with a disease)? What are some examples of things that can cause symptoms of a disorder?
A disorder is caused by non-living (abiotic) or environmental stress. Examples of these stressors include: Moisture extremes - drought, flooding, over-watering Temperature extremes - heat, sun-scald, freezing Physical injury - human, animal, weather (hail) Chemical - fertilizer, salt, pesticides, nutrient imbalances
Aside from making an agricultural ecosystem more resilient to disturbances, what are some other reasons that biodiversity is helpful in agriculture?
A diverse collection of organisms plays several roles in agriculture, including: Nutrient cycling (recycling organic matter - think the nitrogen cycle) Detoxifying or breaking down contaminants Biological pest control Pollination
Why is genetic diversity essential for making sure that we can sustain agriculture into the future?
A diverse population is resilient and capable of adapting to a change in the environment. In the case of agriculture, this could also be a change in the production system. Maintaining genetic diversity means that we will have access to traits that we may need in "varieties of the future", such as disease and pest resistance, adaptation to harsh conditions or low inputs, etc.
What is Bt and how does it work?
Bt refers to the soil bacterium Bacillus thuringiensis. Bt is a biological insecticide that is used by organic growers. Bt produces a toxin that specifically targets some caterpillars. When the caterpillar ingests the Bt spores and toxin, the alkaline midgut of the caterpillar causes the toxin crystals to dissolve. The toxin starts to damage the lining of the midgut, and the pH of the midgut starts to go down. With the lower pH, the Bt spores germinate and the Bt reproduces. The caterpillar fills up with bacteria and it dies.
What are some of the consequences of having more physical distance between producers (farmers) and consumers? Are there any advantages?
Consequences: food travels farther, longer time between harvest and consumption, consumer is less aware of production issues (seasonality, crop losses, effects of weather, labor requirements), lower prices to farmers but higher prices for buyers Advantages: increased availability of produce out of season, permits specialization and consolidation which can increase production efficiency, making food cheaper for the consumer.
List and describe several strategies that farmers might use to conserve their soil resources; e.g. prevent erosion.
Contour planting - crops are planted in strips perpendicular to the slope on a field Terracing - crops are planted in narrow level areas that are created on very steep hillsides Perennial crops - do not require tillage, so therefore hold the soil in place better than those which require that the soil be tilled up every year.
The industrial revolution had a major impact on agriculture. Give three examples of industrial revolution developments and for each, explain how it impacted agriculture and food production.
Farm mechanization - replaced animals (and therefore made manure use impractical), required capital investment by farmers, increased the amount of production possible on a given amount of land with a given amount of labor Transportation - enabled food production to take place a lot further away from population centers Manufacturing Technology - enabled mass production of farm equipment (tractors, and more specialized things that tractors pull), farm chemicals (synthetic fertilizers and pesticides), etc.
We discussed one example of a GE fruit crop, the transgenic 'Rainbow' papaya, which is resistant to papaya ringspot virus. It was released to growers in Hawaii in 1998. What are some of the effects that it has had?
Growers adopted the transgenic papaya, and production was so good that supply exceeded demand and prices paid to the growrs fell. Non-transgenic papaya can now be grown again in HI (because the abundance of transgenic papaya reduces the amount of trees that could act as a source of infection for the virus). Some organic and conventional non-transgenic papaya growers are concerned with the drift of pollen from the GM papaya onto their crops. Other viruses still infect the papaya, it is not immune to other diseases.
What is the difference between a hybrid crop and a genetically modified or genetically engineered crop?
Hybrid crops are developed by crossing two varieties of a crop plant (e.g. one corn variety with another corn variety). They are generally more uniform and have higher yields than inbred or 'open-pollinated' varieties. GM or GE crops refer to plants that contain a gene from another organism. That gene could be from a plant, or a bacterium (like with Bt corn, which contains the gene from the bacterium Bacillus thuringiensis). Hybrid crops are often grown on organic farms; GM crops are not permitted.
What are some strategies that we can take to protect and save genetic diversity in agricultural crops and livestock?
Maintain centers of diversity (which are often found where crops were originally domesticated). Landraces and wild relatives are often found in these spots. - Maintain gene banks, which store seeds, plant material, and reproductive cells (eggs and sperm) of animals. - Actively use genetic resources that are preserved in gene banks and that have been collected by plant breeding. - Have smaller-scale producers and interested hobbyists preserve heritage or heirloom varieties in various grassroots efforts.
Why would farmers that plant Roundup-Ready crops still need to look for weeds (and have a strategy for removing them)?
Natural genetic variation among weeds will allow some weeds to tolerate Roundup application. If those weeds are allowed to reproduce, Roundup-resistant weeds will develop in these fields and Roundup will no longer be an effective herbicide.
What does the word "organic" mean, chemically speaking? How does this relate to "organic" agriculture?
Organic = carbon-containing. All forms of plant and animal life are carbon-based, so as they decompose they are referred to as 'organic matter'. Organic agriculture relies primarily on decomposing plants and animals, or organic matter, as a source of fertility in the soil and for the next crop.
What is Soil Organic Matter, and why is it considered important and beneficial?
Organic matter is the sum total of the dead, decomposing, and completely decomposed organisms in the soil. Decomposing OM provides food for living soil organisms. As it is broken down, it produces sticky substances which promote aggregation and good soil structure, which in turn helps water infiltration and water-holding capacity. Stable decomposed organic matter particles have high cation exchange capacity (CEC), which means they are hold plant-available nutrients well.
Nitrogen (and all other elements) exist in many forms within the environment. List at least 4 forms of Nitrogen found in the environment. For each, tell whether plants can use that form directly. *you should understand the nitrogen cycle completely*
Organic nitrogen - this is nitrogen that's part of organic compounds within living plants and animals (like amino acids, DNA, etc). It is not available for plants until it is decomposed and broken down. Inorganic forms of nitrogen include: Nitrogen gas (N2) - found in the atmosphere, not available for plants to use Nitrate (NO3) -found in soil, is useful for plants Nitrite (NO2) -found in soil, is useful for plants Ammonium NH4 -found in soil, is useful for plants (a few plants take it up directly, but most require that it be converted by microbes into NO3 first) Ammonia NH3 - this is a volatile gas, not taken up by plants
We spoke about the long-term research project that several groups have been working on; development of perennial wheat. What would the advantages be of having a perennial wheat rather than the annual wheat we currently grow?
Perennial wheat would not require annual tillage before planting; which would reduce soil erosion. The deep root system of a perennial grass would be better able to access deep water and nutrients, and might be more resistant to stresses like drought. It would also hold the soil better than the puny root system of annual winter wheat. Another advantage would be that farmers would not have to purchase or save seeds, assuming that the perennial wheat would live for several years.
Name and briefly describe the process by which plants harvest energy from the sun. List the inputs and outputs of this process, and describe when and where it occurs within the plant.
Photosynthesis occurs in the chloroplasts within plant leaf cells. Inputs are water, carbon dioxide and light energy, and outputs are glucose, water, and oxygen.
What could be some positive and negative consequences of having a consistent federally-regulated organic label? (list at least 3 of each). Does this favor smaller or larger farmers? How could this effect the consumer?
Positive: consistent meaning, interstate trade of organic produce is easier, increased value of organic, increases overall organic acreage Negative: interstate trade of organic produce is easier, makes it easier for growers driven by profits rather than philosophy to enter the marketplace, many of the ideals described in regional labels are not included in the federal standard Note - there are many other possible answers! Tends to favor larger growers, because they have the capital and infrastructure required to export organic produce out-of-state, and because there is a high return (value) in doing so Consumers can more readily get organic produce, but it may not necessarily have all the features they have traditionally associated with organic (local, fresh, etc.).
List and briefly describe advantages reduced tillage systems.
Pros: -Avoiding tillage reduces leaching and erosion -Tillage that incorporates oxygen into the soil speeds up the decomposition of organic matter; reduced tillage systems maintain organic matter better than conventional tillage systems -If you can reduce the number of times that you need to operate equipment on the field, it will save fuel and time
If a farmer normally uses her own cow manure, but then sells her cows and starts buying manure from her neighbor, can she use it the same way? Why or why not?
She might be able to - but she would need to know whether it's from the same kind of animal (cow vs. poultry vs. hog?) and whether the final product has the same percentages of different nutrients as her cow manure did. Animal manures may be very different according to diet, type of manure, amount of bedding mixed in, etc.
Agricultural practices have the potential to negatively impact natural resources, and therefore reduce the ability of ecosystems to provide the services you described above. Describe a few examples of how agricultural activities can harm natural resources.
Soil degradation - soil is lost through erosion (wind and water) and loss of nutrients through overuse (mining) in some parts of the world. Water - Silt & Sediment contaminate surface waters, destroying habitats for aquatic organisms. Fertilizers contaminate water with nutrients, which can cause blooms of growth of organisms and then oxygen-starved conditions. Pesticides, Pathogens, and Heavy Metals can contaminate surface and ground waters. Overdrawing ground water can result in salinization of water near coastal areas. Genetic Diversity - Widespread use of monoculture increases the vulnerability of specific fields to epidemics (insects, diseases etc.); Genetic Diversity can be lost by wide adoption of a few high-performing varieties; this means that the population of crops grown are less able to respond to changes in their environment
What is the difference between symptoms and signs of a disease? Give at least five examples of types of symptoms, and give one example of sign.
Symptoms = physical expression of disease, i.e. abnormal appearance Examples include - chlorosis, necrosis, blights, rots, spots, holes, leaf distortion, and more. Signs = physical evidence of the pathogen that is causing the disease Examples include - the mycelia of fungi, bacterial oozes, etc.
In the national organic standards, what is the "national list"? Give an example of an item that appears on this list and explain whether it can or cannot be used on organic farms.
The National List appears in the organic standards. In general, all synthetic materials are prohibited and non-synthetic materials are allowed for use in organic farming. The National List is the list of exceptions - synthetics that are allowed, and non-synthetics that are not allowed. There are many examples, which you could find in the reading. I discussed a few of them in class.
Who decides which inputs (fertilizers, pesticides, etc.) can be used on USDA-certified organic farms?
The National Organic Standards Board (NOSB)! The NOSB is a group of 15 individuals (consumers, farmers, scientists, organic certifiers, food processors, etc.) that are appointed by the USDA to define and update the federal organic standards.
Why is it important to have many (abundant) diverse types of organisms living in the soil?
the more species are present in an agroecosystem, the less likely crop damage is to occur different populations keep one another in check through predator-prey balance. Different types of organisms perform different ecosystem functions... e.g. some are decomposers, some are predators, some are herbivores, etc. I didn't mention it in class, but the more ecosystem functions that are filled, the more efficiently energy is used in that system. Another way to think about it is that fewer resources are wasted.