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Agricultural Methods and Pest Management. Chapter 15. The Development of Agriculture. Early ancestors obtained food by hunting and gathering Agriculture has developed from a need to provide for a growing population This has involved various kinds of innovations.

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Agricultural Methods and Pest Management

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the development of agriculture
The Development of Agriculture
  • Early ancestors obtained food by hunting and gathering
  • Agriculture has developed from a need to provide for a growing population
  • This has involved various kinds of innovations
1 shifting agriculture a k a slash and burn
1. Shifting Agriculture (a.k.a. “Slash and Burn”)
  • Cutting down and burning trees and small vegetation to release nutrients from this biomass
  • While soil is suitable a few crops can be grown (2-3 years)/Then site is abandoned to allow forest to recolonize
  • Temporary use prevents much erosion
Used in places with nutrient-poor soil and on steep slopes
  • Also where human population is low, to reduce the size and number of these plots
  • Planting a mixture of crops in one garden plot
  • Taller plants may help shade-requiring plants/May reduce insect pest problems
  • Because only temporary, reduce insect infestations
2 labor intensive agriculture
2. Labor-Intensive Agriculture
  • Used when:

A) site does not allow for mechanization

ex. mountainous regions or small plots

B) when the kind of crop does not allow it

    • ex. rice

C) Economic condition of people (less-developed regions can’t afford machinery)

    • Ex. Many parts of Africa, Asia, and Central/South America
3 mechanized agriculture
3. Mechanized Agriculture
  • Used Typical in North America, Europe and parts that have:
  • A) money and
  • B) large amounts of land available
  • This Requires large expenses and fairly level land
  • Has greatly increased amount of food available
  • Planting of one crop on a large tract of land
  • Reduces the need for change of machinery
  • Drawbacks: increases erosion, reduces needed organic matter

Green Revolution

  • Benefits: Advances in agriculture have lead to more food production
  • Drawbacks:
  • 1.requires use of pesticides,
  • 2. more water, and
  • 3. dependence on industries for specialized seeds
fossil fuel vs muscle power
Fossil Fuel vs. Muscle Power
  • Mechanized agriculture requires extensive use of fossil fuels although food production has dramatically increased
  • 2 factors that drastically affect food prices:
  • 1. Change in oil cost or
  • 2. availability of fuels
impact of fertilizer
Impact of Fertilizer
  • Valuable because increase soil nutrients removed by plants
  • Three nutrients in short supply: nitrogen, phosphorus, and potassium (Macronutrients)
  • Micronutrients needed in small nutrients include boron, zinc, and manganese
agricultural chemical use
Agricultural Chemical Use
  • Pesticide- chemical used to kill or control unwanted populations (fungi, animals, or plants)- called Pests
  • Weeds-unwanted plants
pesticide categories
Pesticide Categories
  • Insecticides- kills insect populations
  • Fungicides-fungal pests that weaken plants
  • Rodenticides- kill mice and rats
  • Herbicides- kill weeds
  • Pesticides-may also be called biocides b/c can kill variety of living things
Pest called target organismwhen inhibits specific pest
  • Most pesticides not specific so they may kill nontarget organisms
  • Persistent pesticides remain active long period of time
  • Nonpersistentpesticides break down quickly
  • DDT-first insecticide used (P.334)
  • It is persistent
  • half-life of 10-15 yrs.
  • Affected many non-target organisms
categories of insecticides
Categories of Insecticides

1. Chlorinated Hydrocarbons

  • Contain carbon, hydrogen, and chlorine
    • Ex. DDT
  • Stable-effective for long time but accumulate in soil and food chain
  • Many no longer used b/c of negative effects
2 organophosphates and carbamates
2. Organophosphates and Carbamates
  • Nonpersistent/ Decompose in hours or days
  • Not species-specific
  • More toxic b/c affect nervous system-uncontrolled spasms-result in death
  • Must apply w/special equipment & have training
  • Control unwanted vegetation
  • Important since take nutrients and water from soil/crops need these
  • Type of herbicide-Auxins- disrupt normal growth/death
  • 2 types of fungi:
  • 1. Decompose organic material & Parasites on crop plants
  • 2. Used as fumigants (gases), sprays, and seed treatments
  • Rodents destroy food supplies/carry disease
  • Warfarin-one of most widely used-causes internal bleeding in animals, even other mammals
  • Must be careful
problems w pesticide use
Problems w/Pesticide Use
  • Persistence
  • Bioaccumlation/biomagnification
  • Pesticide Resistance
  • Effects on Nontarget Organisms
  • Human Health Concerns
1 persistence
1. Persistence
  • B/c of their stability, have become long-term problem
  • Attach to small soil particles & can be carried anywhere by wind or water
  • Been found in the ice of the poles/ human body tissues
2 bioaccumulation biomagnification
2. Bioaccumulation/ biomagnification
  • Bioaccumulation- accumulating higher & higher amounts of material in animal bodies
  • If animal w/pesticides eaten by another, then concentrates in that animal-leading to disease or death
  • Biomagnification- increasing levels of substance in higher-trophic-level organisms (Fig. 15.9)
3 pesticide resistance
3. Pesticide Resistance
  • Pest populations may become resistant to pesticides
  • Ones with characteristics that tolerate the chemicals may live to reproduce/their offspring may also posses these
4 effects on nontarget organisms
4. Effects on Nontarget Organisms
  • Most are not specific/ kill beneficial species as well as pests (Mainly Insecticides)
  • Most often becomes irreversible tactic since stopping my result in rapid increase of pests
5 human health concerns
5. Human Health Concerns
  • May result in short-term or long-term health effects
  • Pesticide poisoning needing medical treatment in the U.S. are in the thousands per year/ World wide-? (many go unreported)
  • Dues to improper applications/unaware of precautions when applying
  • Many have been proven to cause mutations, cancers, abnormal births in experimental animals
  • Studies of exposed farmers over years have higher levels of certain cancers
why are pesticides so widely used
Why Are Pesticides So Widely Used?
  • Has increased the amount of food that can be grown worldwide
  • The economic value: farmers increase in profit from crops/ businesses increase from pesticide sales
  • Control insect populations that cause many health problems
alternative agriculture
Alternative Agriculture
  • All nontraditional agricultural methods
  • Includes the following:
  • Sustainable Agriculture-Seeks methods to produce safe food in an economically viable manner while enhancing health of agricultural land
  • Organic Agriculture-Advocates avoiding the use of chemical fertilizers and pesticides
techniques for protecting soil and water resources
Techniques for protecting soil and water resources
  • Two problems for soil: Compaction and reduction in organic matter
  • Reduce these problems by: farm equipment traveling less over soil (compaction) & leaving crop residue on the soil (increases organic matter)
precision agriculture
Precision Agriculture
  • Uses modern computer technology and geographic information systems, based on soil and topography, to automatically vary chemicals applied to the crop at different places within a field.
  • Less fertilizer is used, and used more effectively.
integrated pest management
Integrated Pest Management
  • Uses a variety of methods to control pest rather than pesticides alone
  • Must understand all ecological aspects of the crops and the pests to which they are susceptible
disrupting reproduction
Disrupting Reproduction
  • Pheromone- chemical released by females to attract males
  • Spraying areas with synthetic odors confuses males & they don’t find female mates Ex. Moths
  • Male sterilization- growing sterile males to mate with females also greatly reduces populations Ex. Screwworm fly
using beneficial organisms to control pests
Using Beneficial Organisms to Control Pests
  • Ladybird Beetles or Ladybugs- feed on aphids which can destroy crops, such as orange tree decline in California in late 1800s
  • Some insects can also control weeds
  • Naturally occurring pesticides in plants help control pests (garlic plants-Japanese beetles)
developing resistant crops
Developing Resistant Crops
  • Genetic engineering- Inserting specific pieces of DNA into genetic makeup of organisms
  • Known as genetically modified organisms
  • A bacteria BTI produces material that destroys lining of insect guts, this gene has been inserted into several crop plants (Corn)
modifying farm practices
Modifying Farm Practices
  • Destroying crop residues to prevent overwintering ground for insects
  • Crop rotation-planting a mixture of crops reduces specific insects that buildup from same crop being planted year after year
selective use of pesticides
Selective Use Of Pesticides
  • Identifying when will have greatest impact on pests-reduces amount used
  • Integrated pest management