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“Sustainable Agriculture: Looking at Soils, Seeds & Nutrition”

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Presentation on theme: "“Sustainable Agriculture: Looking at Soils, Seeds & Nutrition”"— Presentation transcript:

1 “Sustainable Agriculture: Looking at Soils, Seeds & Nutrition”
Global Science, Ch. 6 p

2 Section 6.1 - Introduction to soils
Terrestrial life is supported by soil Good soil = Healthy Ecosystem = Healthy Living No soil when Earth was formed Primitive plants began soil formation processes Growing plants also contributed Roots Organic matter

3 Soil - mixture of minerals, organic matter, water and air with a definite structure and composition and forms the surface of the land

4 Section 6.1 - Background Information
Horizons - layers of soil Three major horizons Top soil Subsoil Parent material More or less layers may be present Layers make up the soil profile

5 Soil profile - succession of distinctive soil layers from the surface down to the unchanged parent material O-horizon: top layer; organic matter A-horizon: top soil; economically valuable; 1” to 24”; “zone of leaching” B-horizon: subsoil; “zone of accumulation”; poor organic content C-horizon: not part of the soil; parent material; no distinct lower limit

6 Decomposers break down organic matter to release sulfates, nitrates, and phosphates
Rate of soil formation depends on “parent” material, region, climate and surface features Hard parent material = 100’s of years Soft parent material = 20 to 30 years

7 Soil color can serve as an indicator of the quality of soil

8 Upper Layer - lots of life
Maintains porosity Mineral particles are classified into three main groups Large coarse = sand Somewhat finer = silt Extremely fine = clay Relative samples of particles determines soil texture

9 34% 32% 34%

10 Suitability for agriculture depends on both texture and structure
Most productive have these characteristics Crumbly texture Well aerated Retains water Fertile soil must be able to supply the complete set of nutrients to the plant Chemical analysis determines what essential nutrients are present or deficient and how much fertilizer to add Essential nutrients: N, P, S, K, Ca, Mg, C, H, and O Minerals released through weathering Application of limestone, commercial fertilizer, manure

11 Plants require large amounts of these elements: N, P, K
Reserves are depleted quickly, measures can be taken to replace

12 Macronutrients & Micronutrients
N - stimulates above ground growth, green color, determines plants ability to use other nutrients; replaced by growing legumes, add organic matter, commercial fertilizer P - abundant in fruits of plants and seeds, root hairs (rapid uptake of water nutrients), energy transferring processes; replaced by manure and commercial fertilizers K (potash) - vigor and vitality of the plant, healthy root, synthesis of starch and translocation of carbohydrates; replaced with commercial fertilizers Ca deficiency rarely a problem due to placing lime on soil, to increase pH; Mg all soils have Mg sources, deficiency corrected with pulverized dolomite or limestone; S found in organic matter Mn, Fe, B, Cu, Zn, Mo, and Cl - trace amounts required; essential to animal health and maintenance of health in humans

13 pH - refers to the degree of acidity or alkalinity (basicity) of a substance; ranges from 0 - 14
Below 7 is acidic Above 7 is alkaline Common soils range from

14 Section 6.1 - Natural Selection
Process by which the organisms that survive have genetic characteristics that are naturally selected for in the environment Certain characteristics increase survival; increase in reproductive success Survival of one form over another leads to changes in proportions of certain genes within the population


16 Section 6.2 - Non-Human Organisms & Agriculture
Majority of organisms survive on products produced through agriculture; either directly or indirectly Spoilage - breakdown by fungi, bacteria and other decomposers; competition for food Most serious and widespread threat to human food supply is insects Estimated 30,000,000 (million) species Outweigh humans 12:1 (pounds)

17 Section 6.3 - Natural Selection, Pests, and the Food Supply
What do you think is the best way to get rid of insects and protect our food supply?

18 Section 6.3 - Natural Selection, Pests, and the Food Supply
What do you think is the best way to get rid of insects and protect our food supply? Insecticides Integrated Pest Management

19 Ecosystem - “marvelous” dynamic thing, energy flows through and powers the system, can be disturbed and damaged; ecosystems are linked to other ecosystems

20 Section 6.4 - Plant Nutrition
Food chain is made of three levels Producers Consumers Decomposers Producer needs: Sunlight, water, oxygen, carbon dioxide, minerals Photosynthesis Respiration Heat Essential minerals (13): N, K, Ca, P, Mg, S, Mn, B, Fe, Zn, Cu, Mo, Cl

21 Section 6.5 - Animal Nutrition
Nutritional needs of animals include: Water Minerals Proteins Fats Oxygen Vitamins minerals

22 Obtain energy either directly or indirectly from green plants
Breaks down energy rich molecules from photosynthesis to less energetic molecules animals use as building blocks Metabolism - chemical reactions that take place inside the body; nutrition and uptake of minerals is necessary for metabolism Water - regulates body temperature, transports nutrients, carries waste, participates in metabolic reactions Adult human body is 65% water How much water are you?

23 Oxygen - required for respiration
BOTH PLANTS AND ANIMALS CARRY OUT RESPIRATION Essential mineral elements - involved in the function of nerves and muscles, formation of bones and teeth, activation of enzymes, transportation of O (Fe) Vitamins - organic molecules necessary for higher organisms to perform specific biological functions; vitamins and enzymes often work together Vitamin K - blood clotting Proteins - broken down into amino acids, reassembled to form different proteins, organ structure, enzymes, antibodies, hormones, metabolically active compounds

24 Carbohydrates - energy; adequate supply of carbohydrates prevents the breakdown of proteins for energy “protein sparing” Fats - maintains cell membrane structure and function, building blocks of hormones, concentrated source of energy, carry some vitamins, provide insulation and protection for some organs Proper nutrition is important for growing healthy plants and animals; excess amounts is converted into fat

25 Section 6.7 - Seed Banks & Insectaries
At the time the book was published the world was making enough food to feed all of its citizens Possible ways of increasing/expanding our food production and feeding more people, but some practices are harmful Farming marginal land Reliance on new high-yield hybrids Hybrids - mix of plants that does not occur in nature Most profitable to plant 1000’s of acres of the same crop Decrease genetic diversity Very risky Lack of germplasm (hereditary material necessary to resist pests or fight environmental stresses

26 International Board of Plant Genetic Resources (IBPGR)
Genetic diversity of plants must be preserved to recover from potential epidemics and natural disasters Large expanses of various ecosystems must be preserved Seed banks International Board of Plant Genetic Resources (IBPGR) Established in 1974 Create and coordinate a worldwide germplasm resource conservation and centers Funded by World Bank, United Nations Development Program Future needs - plants will be needed to survive a variety of different climate changes; storehouse of genetic material is ourr best chance for survival; Researchers must be able to draw on the numerous plant and animals species that re quickly diminishing

27 Biological pest control
Insectaries - place where beneficial insects are raised for use in controlling certain plant species and insect pests Biological pest control Considered to be a safe practice Exotic species must be strictly quarantined before made available for general release Approximately 25 government funded insectaries in the United States

28 Section 6.8 - Plant Biotechnology and Agriculture
For centuries farmers have used a variety of techniques to improve the quality of their crops/livestock Selective breeding Called hybridization in plants Still used today Plant Biotechnology Transfer of very specific genes from one plant to another Only adds beneficial traits


30 Section 6.9 - The Concept of Carrying Capacity (K)
Maximum number of given organisms an ecosystem can support Number of people the Earth can support is tied to the standard of living Section Various Perspectives on Carrying Capacity Our Population Should Be Kept Well Below 10 Billion Earth Can Support Many More Vegetarians Than Meat- Eaters Technology and Human Ingenuity Will Keep Us Fed

31 Our Population Should Be Kept Well Below 10 Billion
Estimated that food production will likely ever grow to more than 9 times what it is now Carrying capacity of Earth is well over 30 billion by 2075 Most of whom will be near starvation Even if population levels off near 10 billion by 2050 there will need to be extensive management of resources to have any comfort For everyone to have enough food and environmental quality to be maintained the population needs to stay below 10 billion

32 Earth Can Support Many More Vegetarians Than Meat-Eaters
Belief that Earth’s carrying capacity could be extended if humans quit raising animals for food and use the land to grow grain for human consumption (2nd Law of Thermodynamics) Average steer: 16 lbs. grain/soy = 1 lb. of meat on the plate Eating “lower on the food chain” allows Earth to support more people Same amount of food material feeds 4 times as many people in India and China than it does in the United States and France 210 million Americans = 1.5 billion Chinese

33 Technology and Human Ingenuity Will Keep Us Fed
Today farmers are producing 5 times as much food product as they did in the 1920’s Enough food produced to ALL Americans plus 100 million people abroad Emerging technologies may enable farmers to further expand the amount of food they produce High-Yield Farming - collection of techniques designed to maximize the amount of food produced per acre of farmland Sustainable over the long term must attend to water conservation and prudent pesticide use

34 Section 6.11 - So How Many People Can the World Support?

35 Table 6.52 - Summary of Eight Estimations of Maximum Population

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