1. Agricultural Methods and Pest Management
Chapter 15

2. 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

3. 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

4. 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

5. Polyculture 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

6. 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

7. 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

8. Monoculture 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

9. 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

10. 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

11. Agricultural Chemical Use
Pesticide- chemical used to kill or control unwanted populations (fungi, animals, or plants)- called Pests
Weeds-unwanted plants

12. 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

13. Pest called target organism when inhibits specific pest
Most pesticides not specific so they may kill nontarget organisms
Persistent pesticides remain active long period of time
Nonpersistent pesticides break down quickly

14. Insecticides DDT-first insecticide used (P.334) It is persistent
half-life of yrs.
Affected many non-target organisms

15. 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

16. 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

17. Herbicides Control unwanted vegetation
Important since take nutrients and water from soil/crops need these
Type of herbicide-Auxins- disrupt normal growth/death

18. Fungicides 2 types of fungi:
1. Decompose organic material & Parasites on crop plants
2. Used as fumigants (gases), sprays, and seed treatments

19. Rodenticides Rodents destroy food supplies/carry disease
Warfarin-one of most widely used-causes internal bleeding in animals, even other mammals
Must be careful

20. Problems w/Pesticide Use
Persistence
Bioaccumlation/biomagnification
Pesticide Resistance
Effects on Nontarget Organisms
Human Health Concerns

21. 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

22. 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)

24. 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

28. 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

29. 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

30. Contd.
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

31. 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

32. 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

33. 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)

34. 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.

35. 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

36. 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

37. 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)

38. 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)

39. 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

40. Selective Use Of Pesticides
Identifying when will have greatest impact on pests-reduces amount used
Integrated pest management