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.
So I know what terracing and contour farming are, but I feel like besides the fact that terracing is more like steps they are basically the same. Is there any difference really between the two because they both seem to be the same idea of forming strips that are perpendicular to the slope on a hill or mountain to help avoid erosion, so why choose one over the other?
We just learned about soil degradation through Desertification, Salinization, Waterlogging, and Decreased Fertility.
Desertification is exactly what it sounds like. It is when more fertile land is turned into desert mostly due to drought. Although, human activities such as convention tillage, overgrazing, and salinization contribute to desertification as well. Approximately 30% of crop land and range land is affected. There are various things humans can due to help prevent desertification such as stopping destructive planting and planting “greenbelts” and agroforestry. Agroforestry is the integration of forestry like shrubs and trees into crop land and range land to stop erosion and desertification.
Map of Areas Affected by Desertification
Salinization is when irrigation from farming leaves behind salts. The problem is worse in very arid environments. 70% of cropland is affected. There are solutions to this, but they are extremely complex and expensive. Flushing the soil is when farmers pump in water to the affected area and drain it so that the salts will wash away. The problem with is the water is expensive and needs somewhere to go afterwards.
Salinization of Soil
Waterlogging is when irrigation from farming or soil flushing raises the soil’s water table. If the water table reaches the roots of crops it an lead to root rot(a fungal disease) and lack of oxygen. Around 1/10 of irrigated land is affected.
Finally decreased fertility is when nutrients like nitrogen, potassium, and phosphorus are taken up out of the soil and not replenished. There are many causes for this such as overplanting. Rotating crops is effective in combating this problem. Also organic and inorganic fertilizers are used to replenish soil. The difference between these fertilizers is organic has carbon based nutrients.
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.”
To start off, we discussed various causes of degraded soil such as:
Erosion
Desertification
Salinization
Waterlogging
Decreased Fertility
When it comes to humans, overgrazing, deforestation, and cropland agriculture are the greatest threat we pose to soil quality.
Farming requires the removal of the O Horizon so that the topsoil layer is exposed, but the loss of topsoil is what farmers are most concerned about. It takes centuries to replenish just 1 in. of topsoil, so losing it can be very costly. To make topsoil, weathering occurs to build up the inorganic parts, and decomposition occurs to build up the organic part of the soil.
Soil, like trees, is a renewable source and when you lose organic matter in the soil, its fertility goes down. (In general, the darker the soil, the more fertile)
We also talked about soil erosion and how water is the number one erosion force. The known types of soil erosion due to water that we talked about (but don’t need to know in great detail) are:
Splash
Sheet
Rill
Gully
Towards the end of class, we focused on how we can reduce soil degradation. One way was by using proven agricultural techniques like planting crops without disturbing the soil, which is called low or no-till farming. Keeping the soil covered with vegetation too can help soil fertility. Other types of farming techniques include terracing (which works best on steep mountains), contour farming (which works best on hilly terrain), strip cropping/intercropping, alley cropping, or farming using windbreaks or shelterbelts. Below are images of some of these techniques so you can get a better idea of what some of them talk about.
Terracing
Contour Farming
Windbreaks
We watched this informative video in class to better understand soil conservation:
After the Dust Bowl, the government began to get involved in soil protection, and these acts were passed:
Soil Conservation Act and Soil Conservation Service (1935-Now the NRCS)–this act created soil conservation programs
Food Security Act (1985)– this act established subsidies paid to farmers for taking erodible land out of production to plant trees or grasses. (Basically the farmers would be paid to not farm)
As the book says, we use 38% (small percentage, but not all can be used for farming because of ice and deserts and other areas that aren’t fit for farming) of the Earth’s surface area for agriculture. (The “most devastating activity to the environment.”) We mostly use the temperate regions for agriculture (prairies and temperate deciduous).
It takes hundreds to thousands of years to make just 1 inch of soil (depends on the region).
Agriculture is separated into two categories: crops (cropland) and livestock (rangeland).
Soil is a potentially renewable resource, which means we need to manage our consumption carefully so we don’t use it faster than it is made.
50% Sand, Silt, and Clay (different sizes). aka Inorganic material.
5% organic material, composed of detritivores, decomposers, and decaying organic matter
Detritivores break leaves and other matter into smaller parts for the decomposers (which are fungi and bacteria) that break those down into Nitrogen, Phosphorous, and Potassium (NPK), the macronutrients that plants need most.
3. Soil Formation
As we already learned, there are three types of weathering (the “principle agent to soil formation”)
1. Physical–plate tectonics and ice wedging
2. Chemical– H20+CO2–>H2CO3
3. Biological–Roots
This brings large particles to small particles:
Weathering makes larger particles into smaller ones: Sand, then silt, then clay
Definitions: Soil profile: The cross-section as a whole from surface to bedrock.
Soil Horizon: Each specific layer of soil
There is a handout on Soil Horizons in the box, but if you need another source… (Only layers O, A, E, B, C, and R are on our sheet, so ignore P and D.)
A few things we said about the different horizons in class:
If there is too much leaching, all of the NPK ends up at the bedrock (level R).
Tree roots can only reach to the very top of the zone of accumulation, so if too much of the NPK is leached downwards, the tree roots cannot reach them.
Level A is what is known as topsoil, which is (hopefully) rich in humus, which is a dark mix of rich nutrients (like potting soil).
The largest particles are at the bottom and the smallest are at the top
