Sources and Sinks

1. Sources and Sinks Sources or Supply Deports- Sources of Resources (Soil, Water, Forests and Biodiversity, Mineral Resources) Sinks or Waste Repositories- where we dump things. Pollution sinks (solid wastes and chemical pollutants).

4. Ecosystem Services: A Newly Defined Resource • Public Goods that are not priced by the market economy. • “Watershed Services”. Downstream residents pay upstream farmers to maintain forest- provides hydrological services. • Paying farmers to grow trees for their carbon capture functions • Pollination services from bees.

5. Soil Resources • Soil a variable mix of inorganic and organic compounds, a “living layer” of the biosphere. • 98% of human food produced in soil. • Food and fiber crops cultivated on 12% of earth’ surface. 24 % is pasture. Rest is forests, deserts, mountains

6. Amazing Soil Facts!! • An acre of good topsoil may house eleven tons of insects, worms, nematodes, fungi and microbes! • The root system of a single four-month-old rye plant was found to have a surface area of 639 square meters, 130 times the surface area of the aboveground plant • Surfaces of the particles in a single ounce of clay-rich soil-6 acres!

7. More Amazing Soil Facts • Earthworm feces, known as castings-on a single hectare (2.7 acres) in a year, earthworms may deposit 500 metric tons of castings. • To a great extent, the soil organisms do not just make the soil, they are the soil. Soil is almost a living thing itself. • Now, what happens when you apply chemical fertilizers?

8. Impact of chemical fertilizers on the soil-”going over the soils head, like feeding your children white bread”. • “Petrochemicals feed its zombie productivity” Pesticide Treadmill- In 1948 at the dawn of the chemical age, American farmers used 15 million pounds of insecticide and lost 7% of the crop to insects; today they use 125 million pounds and lose 13 percent.

9. Soil Erosion Of earth’s present cropland • Soil eroding on from 16-38%. • In the US, Great Plains states have lost half their topsoils. • Caused by overgrazing of livestock, poor farming practices, and deforestation. • Effects-reduced soil depth, reduced water absorption, and reduction in organic matter (Harper, p. 47)

11. Avoiding Erosion • Terracing • contour plowing • multiple cropping (ground cover crops and corn-beans fix the nitrogen). (Harper p. 86)

14. Water Resources Water is a renewable resource, but • If world’s water were 26 gallons, usable freshwater supplies for humans about one teaspoon. • Very unevenly distributed over earth’s surface. • Recharge rates of groundwater are very slow, about 1% a year.

15. Water Use and Waste • People need 26.5 gallons a day (but in US 36 gallons in an average bath) • 70% of water worldwide is for agriculture, but 70-80% of water in irrigation systems lost to evaporation or seeps into the ground. • Industry is 23% of global water use. Takes 400,000 liters of water to make a car (50 million cars a year) • Only 7-8% for domestic use (Harper p. 49)

16. Water Pollution • Contamination from agriculture: the countries that can afford the most chemical inputs have the biggest problems: the US and Europe. Over 90% of Europe’s rivers have high nitrate concentrations. • In developing countries, 90-95% of all domestic sewage and 75% of all industrial waste are discharged into surface waters without any treatment [sink] • All of India’s 14 major rivers are badly polluted and ¾’s of China’s 50,000 kilometers of major rivers are unable to support fish.

17. Mercury in the Everglades • Remember the Mad Hatter from Alice in Wonderland ? Humans alligator bass gar bream (“brim”) mosquito fish water insects water microorganisms

19. Irrigation a cornerstone of modern agriculture • But much irrigation is “mining” the resource. • Irrigation overdrafts lowered water tables by 20-30 meters in the Tamil Nadu region of India. • Water tables in China declining by 1-4.5 meters a year. • Ogallala Aquifer in Nebraska. One quarter gone by 2020.

20. Drip Irrigation • allows small quantities of water to trickle slowly into the soil over long periods. • sprinkler systems waste a lot of water • Drip systems use less water, because it is applied where the plants need it most - in the region of the root hairs.

21. Irrigation efficiency improvements have helped stem the Ogallala aquifer’s depletion. • Since it peaked in 1974, water use in the Texas high Plains has fallen by 43 percent. • Annual average of Ogallala depletion has fallen from 2 billion cubic meters during the late 1960s to 241 million cubic meters in recent years

25. Deforestation • Two-thirds of forests that once existed are gone (historical deforestation for agriculture). • 12% of earth’s surface is boreal forests (Canada, Russia, Scandinavia) • Temperate Zone forests tend to be stable or recovering. • Most current losses in tropical forests.

26. Tropical Forest Biodiversity • Tropical forests constitute only about 5% of the earths surface, but have 50% of all terrestrial species, 4-6,000 species lost a year in tropical forest. • Economic value of forest-medicinal plants, • Medicine Man with Sean Connery..

27. Initiatives to Preserve Forests • Promoting Sustainable Use. • Debt for Nature Swaps • Preserving Nature in Place • Gene Banks and Repositories • Bioprospecting • International Treaties (harper, page 63)