PDS AP Environmental Science 8th Period 2010-11

Alum Richard Gee (’10) just sent me this link to a The Economist article and map about which countries are growning genetically modified crops. I wish we had more time to spend on GMOs, but with me out of town it was not meant to be this year. I’m not too concerned for you all on the AP exam as GMOs made it as a free response topic two years ago, so I doubt it will come around again this soon. Interesting regardless as this is becoming more prevalent as industrialized agriculture spreads. Key points from the brief article:

As can be seen in our map, GM technology has been enthusiastically embraced in the Americas and in many Asian countries. By contrast, many European countries are subject to severe restrictions on growing GM crops. Developing countries are planting GM crops at a more rapid rate than rich countries.

Click to enlarge the image.

GMO Crop Production by Country

Hey guys. I am not really sure the difference between gm organisms and artificial breeding. I know that they are both used to better genetically engineer species to create the desirable traits, but I do not understand the difference if someone could please help!

Hey y’all-

So I’m kindof confused between chemical and physical weathering. I understand biological, but chemical and physical seem too similar that I can’t tell the difference between them. For example, I know that rain is an example of physical weathering, but when water reacts with rock to break it down, that is considered chemical weathering. Can anyone help me differentiate the two?

Thanks

I was just wondering if anyone knew exactly which pieces of legislation we need to know for the test, and how much we need to know about them?

Hi guys, I hope you are enjoying King Corn while I am gone this week. The movie obviously focuses on industrialized corn crop production and the many issues it produces. But, the movie also touches on problems created when we feed all that corn to cows (who did not evolved to eat it) in industrial feedlots. Since I can’t be there to discuss it further, here is a brief lesson.

First, watch this short, hilarious clip called “The Meatrix” that raises some of the issues created by feedlots:

*Trouble viewing video clip here, try this link-you can even find sequels!

Second, here is a good summary post by former APE Kevin Chu:

“We are what we eat. For Americans that means we eat a lot of processed foods. When you pick up a bag of potato chips, its easy to see that the product is unnatural, the chip didn’t fry itself and dip it in oil man did that. But what about the meat we eat? In class today we talked about how the meat production industry has changed since the early 1980′s, about the mechanism that replaced the stereotypical small farmer, CAFO’s.

CAFO’s, or Condensed Agriculture Feed Operations (a.k.a. feedlots)is brain child of antibiotics and genetically modified corn. GM corn allows for cheap feed for cows, while antibiotics allows for livestock to bypass population density inhibitors along with an increased growth rate. What this means is that we can now feed more cows, aka produce more meet in less room. That may sound like a simple achievement, but these adjustments allowed for a much higher rate of meat production than other farming methods by fencing animals as tightly as possible, and fattening them as fast as possible.

Just because the CAFO business is booming doesn’t mean that grass fed cattle operations don’t exist. There are still farmers who feed livestock on open pastures or fenced ranged land. But compared to CAFO, the output is so low, increasing pricing that grass fed operations only operate a small consumer niche of the market. Although economic incentives are virtually nonexistent in this market, there are ecological and personal incentives to eat grass fed.

As mentioned in King Corn, the ratio of saturated fat per t-bone in grass fed to corn fed is 5 to 9, almost double, which helps explain rising obesity rates. This along with the fact that cows aren’t meant to eat corn brings up some potential health issues. Other than health issues, by using feedlots, though we are conserving biodiversity by using less land, we promote other environmental issues. With high production of meat comes high production of manure, and methane(global warming gas). Although manure could be a plus since it could be used for fertilizer, with the sheer amount of manure produced by all the cattle, shipping all the manure is not possible and a fair amount of manure will end up traveling down watersheds and causing algae bloom in bodies of water. With high antibiotic use, people worry about the potential of feedlots breeding super drug resistant strains of bacteria also.

Criticism of CAFO’s are different in every country. In Europe, the precautionary principle came first, so GMO’s have been banned along with use of steroids on cattle, destroying CAFO’s. America on the other hand, has embraced the technology producing tons upon tons of corn beef. With no strong health benefits there is no clear winner. I just hope China has grass fed beef, so I don’t have to worry about ulcered cow stomach meat.”

Made by KC.

*Click image to enlarge.

Thursday, February 17, 2011

Today in class, we discussed Soil Degradation and Conservation, Chapter 9 (part IV of study guide), but mostly focused on erosion and ways to prevent erosion.

First, we discussed the causes of degraded soil, which are:

• overgrazing
• deforestation
• cropland agriculture
• industrialization

We also talked about the different types of degraded soil, which are:

• erosion (the dislodging and movement of soil from one area to another. is part of both formation and destruction of soil)
• desertification (due to drought and human activities, occurs most in desert biomes)
• salinization (caused by evaporation of water from soil and leaves salts in soil, result of irrigation)
• waterlogging (attempt to leach salts deeper but raises water table, results in “root rot” and lack of oxygen to roots, too much water in soil prevents nutrients from getting to plant roots)
• decreased fertility

From there, we elaborated on erosion. Erosion is a problem in the A horizon and eroded soil takes centuries to be  replenished. The number 1 erosive force is water, although wind erosion is a problem, too. Erosion occurs faster than soil formation, so this means that soil is a potentially-renewable resource (since it can reform, but very slowly). Soil fertility decreases as organic matter is eroded away, since there the nutrients are being drained from the soil. Erosion is a major cause of water pollution, being that main water pollutant is sediment. Erosion occurs from both natural (ex: rain) and human activities(ex: overgrazing).

Some legislation was created to address problems with soil conservation, including the Soil Conservation Act, which led to the Natural Resource Conservation Service (1935) and the Food Security Act (1985). During the Dust Bowl, the Soil Conservation Act created soil conservation programs and promoted no-till or low-till farming. The Food Security Act provided subsidies for farmers who did not farm on degraded soil and instead planted trees or grasses on this land. These measures were made in order to revitalize the unarable soil.

To combat/prevent erosion, farmers use the following techniques on their cropland:

• Crop Rotation–alternating type of crop grown in a field each season so that the nutrients from corn, for example, aren’t completely drained out of the soil in three growing seasons. This method returns nutrients to the soil, breaks disease cycles, and minimizes erosion that comes from fields laying fallow.
• Contour Farming–plowing furrows sideways across a hillside perpendicular to the slope to prevent rill and gully erosion.

• Terracing–level platforms on mountains with raised edges to decrease the amount of soil lost to erosion (the precipitation will catch less soil as it runs down the mountain, perpendicular to the terraced levels).

• Intercropping–alternating bands of crops slow erosion by providing more ground  cover than a single crop and reduces vulnerability to insects and disease.

• Shelterbelts/Windbreaks–rows of trees or tall, perennial plants to slow wind erosion. Sometimes combined with intercropping when the tall perennials are sources of fruit, wood, or other crops.

• Reduced Tillage–use cover crops and crop residue on soil to restore nutrients to soil and only cut shallow groove into soil to plant seeds instead of inverting the soil. This increases organic matter and while decreasing erosion.

  

  http://www.marketfarmequipment.com/Chisel_Plow_Leveler_-_IHC_2x.gif

  Low-Tillage Machine

We also watched this video in class, which is a basic explanation of erosion, how soil is affected by erosion, and what we/farmers can do to prevent it.

http://www.youtube.com/watch?v=_UeVvUzgJAY

Soil Formation and Structure

“The Nation that Destroys Its Soil Destroys Itself” -FDR

Agriculture is the single most damaging thing we, humans, do to the environment. While “damaging” and “environment” are both very vague terms for a very complex problem, agriculture is responsible for loss of habitat, biodiversity, and the cause of dead zones. But agriculture is also responsible for the feeding of  billions of people. Currently, 38% of land surface is used for agriculture, with the bulk of that land used for crops (the rest is for livestock rangeland). Temperate grasslands and forests are the best farmland for agriculture use. A balance must be struck between the usefulness of agriculture and its environmental consequences, and the answer lies within soil. Soil is a complex mixture of inorganic materials (sand, silt, and clay) that makes up 50% of the soil composition. Water and gases make up 45% of soil, and organic materials, such as detritivores, decomposers, and decaying matter, make up the remaining 5% of soil composition.

Soil is a renewable resource, as it is able to make ‘new’ soil, though this can take 100s to 1000s of years to make 1 inch of good topsoil. Agriculture, if unchecked, can exhaust this topsoil. Soil is made up of layers, horizons, which are as follows: Horizon O-Horizon O doesn’t really count, because it is made up of biome specific material, like leaves and twigs. Horizon A-Horizon A is made up of topsoil, preferably made up dark, organically rich soil called humus (like the dark potting soil). Horizon E-Not all samples have Horizon E. Horizon E is the layer where minerals have been leached out, leaving the soil light colored. The leached out nutrients may collect further down in the sample, in lower horizons. The farther you go down the soil horizons, the more rock you get in each sample. Soil builds upward from rock layers.

The macronutrients in soil are Nitrogen, Potassium, and Phosphorus. Detritivores and decomposers, which are organic, ‘feed’on organic material. They break down the organic material (Ex. by using nitrogen fixation) and release nutrients into the soil. In the central case study in our book, Guatemalan farmers leave a layer of organic material on top of the soil, and as that material is broken down nutrients are realized into the soil.

SOIL FORMATION

Soil has to be formed somehow, and the most important process by which soil is formed is weathering (physical, chemical, biological). Physical weathering can come in the form of ice wedging and tectonic movement, which breaks down rock into smaller pieces. Chemical weathering uses H2O + CO2–> H2CO3 (Carbonic Acid) to break down rock, whereas biological weathering uses lichen and roots as the ‘break down force’. Erosion, a transportation mechanism, cannot occur without weathering. Erosion does not break down rock to eventually make soil, but rather transports it (the most common transportation mechanisms are wind and water).

(https://www.bestcourseforgolf.org/images/soilComposition.gif is where I got the soil composition diagram. Many gardening sites/golf course management sites, like this one, include diagrams of soil composition and instructions on how to enrich soil nutrient content).

(http://www.uvm.edu/place/images/soil_horizons.gif is where the Soil Horizon diagram is from.)