APES Final Review

Agriculture & AquacultureAPES Final ReviewWhere our food comes fromCroplands (77%)Rangelands, pastures & feedlots (29%)Aquaculture (7%)

There are 50,000 plant species that we can eat, yet 14 supply 90% of the worlds calories!!!

Food Sustainability14 varieties of plants2/3 of the world survives primarily on corn, wheat & rice aloneSmall number of species provide for meat & fishThis all leads to food specializationDiseaseEnvironmental degradation Climate change

Industrialized AgricultureHeavy machineryGoal is to produce more food per area of landCharacteristics include high fertilizer use, pesticide use, irrigation, genetic engineering, factory-like conditionsMonoculturesHigh resource use

Case Study: Industrialized Food Production in the United StatesIndustrialized agriculture uses about 17% of all commercial energy in the U.S. and food travels an average 2,400 kilometers from farm to plate.Figure 13-75Traditional AgricultureLabor- intensivePolycultureUsually lower resource useCan have a higher output than IndustrializedLess susceptibility to changes

Traditional Agriculture: Low Input PolycultureMany farmers in developing countries use low-input agriculture to grow a variety of crops on each plot of land (interplanting) through:Polyvarietal cultivation: planting several genetic varieties.Intercropping: two or more different crops grown at the same time in a plot.Agroforestry: crops and trees are grown together.Polyculture: different plants are planted together.

7SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATIONModern farm machinery can plant crops without disturbing soil (no-till and minimum tillage.Conservation-tillage farming:Increases crop yield.Raises soil carbon content.Lowers water use.Lowers pesticides.Uses less tractor fuel.8Contour Farming sloping your growing crops, etc. You run terraces parallel to the ground to stop soil from running down a steep slope. Plowing and planting crops in rows across, rather than up and down, the sloped contour of the land.

9Terracing (what you use for contour farming.) Dirt goes up to hold the dirt in place. Broad, nearly level terraces that run across the land contour. Helps to retain water for crops at each level and reduce soil erosion by controlling runoff.

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SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATIONTerracing, contour planting, strip cropping, alley cropping, and windbreaks can reduce soil erosion.Figure 13-1611Strip Cropping a row crop such as corn alternates in strips with another crop that completely covers the soil, reducing erosion. It catches and reduces water runoff and helps prevent the spread of pests and plant diseases.12Cover Cropping (alley cropping) several crops are planted together in strips or alleys between trees and shrubs that can provide shade (which reduces water loss by evaporation) and helps to retain and slowly release soil moisture.

13Irrigation TechniquesConventional center-pivot irrigation- allows 80% of the water input to reach crops Gravity-flow irrigation- Valves that send water down irrigation ditches. Drip irrigation- Can raise water efficiency to 90-95% and reduce water use by 37-70%.Floodplain irrigation- allowing the natural floods to irrigate the crops. Soils in flood zones tend to be nutrient rich and fertile.14The Green RevolutionIncreased food production using industrialized crop production (heavy machinery)Steps of the Green Revolution1. Plant monocultures of high yield crops (wheat, corn, rice). Often genetically modified.2. Use high amounts of fertilizers and pesticides to increase yield3. Increase the number of crops grown per year

Meat consumption on the riseEffects:More densely packed feedlotsHigh use of grain and or fish mealIncreased need of grain can lead to dependance on other countries

Fig. 13-21, p. 289Trade-Offs Animal Feedlots Advantages Disadvantages Increased meat productionNeed large inputs of grain, fish meal, water, and fossil fuelsHigher profitsConcentrate animal wastes that can pollute waterLess land useReduced overgrazingReduced soil erosionAntibiotics can increase genetic resistance to microbes in humansHelp protect biodiversity17Figure 13.21Trade-offs: advantages and disadvantages of animal feedlots. QUESTION: Which single advantage and which single disadvantage do you think are the most important?

PRODUCING MORE MEATEfficiency of converting grain into animal protein.

Figure 13-2218Harmful Environmental Impacts of AgricultureErosionDegradation of soilWater depletionWater pollutionGreenhouse gassesAir pollutionBiodiversity loss

**according to the EPA, agriculture is responsible for 75% of water quality issues in US rivers & streamsHigher use of BiofuelBiofuel is a renewable energy alternativeHowever, using too much biofuel aggravates the problems brought on by agriculture.Are we replacing one problem with another?AquacultureRaising fish in ponds and underwater cages (43%)Helps with over-fishingDecrease contamination (ex. Mercury)

Fig. 13-24, p. 292Trade-OffsAquaculture Advantages Disadvantages High efficiencyNeeds large inputs of land, feed, and waterHigh yield in small volume of waterLarge waste outputDestroys mangrove forests and estuariesCan reduce overharvesting of conventional fisheriesUses grain to feed some speciesLow fuel useDense populations vulnerable to diseaseTanks too contaminated to use after about 5 yearsHigh profitsProfits not tied to price of oil24Figure 13.24Trade-offs: advantages and disadvantages of aquaculture. QUESTION: Which two advantages and which two disadvantages do you think are the most important?Fishing

Purse SeinesA large purse-like net is put into the ocean and is then closed like a drawstring purse to trap the fish. Tuna is a fish typically caught in purse seinesDolphins are a by-catch of purse seinesLong-line fishingLines are put out that can be up to 80 miles long w/ thousands of baited hooks on them. These are left out free-floating for days and then the boat comes back and picks them up. Pilot whales, dolphins, sea turtles, and birds are by-catch of this technique.Drift-net fishingEach net hangs as much as 50 feet below the surface and up to 34 miles long. Anything that comes into contact w/ these nearly invisible nets are entangled. This leads to overfishingMany unwanted fish and marine mammals, turtles and seabirds are caught.