Agricultural Methods and Pest Management

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 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

14. Insecticides • DDT-first insecticide used (P.334) • It is persistent • half-life of 10-15 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