Geography 2412 Lecture Notes: October 2

Earth’s Resources (Chap. 3):
We start now a survey of natural resources, starting with soil and water. Recall that the most common economic conception of the environment (neo-classical) is as sources of material and energy and a sink for wastes.

There are other ways of seeing the environment, as we’ll discuss later, but for now we’ll stick with the orthodox view. Resources are generally divided between:

· Renewable vs nonrenewable (or stock) resources

Renewables include water, forests, solar and wind energy, etc. Non-renewables include fossil fuels and non-energy mineral resources like gold, iron, etc. Some resources like soil are renewable in the long-term (hundreds of years) but not considered renewable in terms of the typical utilization ( e.g., a farmer who loses soil to erosion will not see it replaced by soil-forming processes in the typical planning horizon of a couple of decades).

While it may seem a straightforward idea that we can assess the amount of re-newable and non-renewable resources avilable to us, there are actually great uncertainties in estimating:

· Reserves (what’s available under various assumptions of price, exploration, extraction and recovery technology, etc.);

· rates of depletion (despite improving statistics, we simply can’t keep track of all extraction and use of things like oil, silver, or groundwater);

· rates of renewal (just how fast does a forest re-grow after it is cut for timber? How fast do aquifers recharge? These are often uncertain estimates).

SOIL Resources (pp. 83-86):

· Soil is an organic and inorganic “living layer” on the surface of the earth of weathered (broken down by wind, water, and freeezing) particles of the rock that make up the earth’s crust. Soil forms at various rates depending on climate of a place, but a few inches of top-soil can takes decades to centuries to form.

· Soil is the basis for agriculture (98% of human food is gown on land).

· Soil is not “renewable” in typical planning time frames (e.g., a farmer may plan to own and work land for several decades, during which only a small amount of new soil will be formed on the land).

Soil degradation occurs as:

Physical erosion: the translocation of soil particles downhill by wind and water, often ending up in streams and rivers as sediment.

Loss of organic content and biota: a reduction in the number and diversity of living organisms in the soil from microbes to worms to burrowing animals. The amount of organic matter in soil also determines how much water it can retain.

Loss of fertility: a reduction of the nutrients like nitrogen, phosphorous, necessary for plants to grow and photosynthesize.

Soils naturally erode (the Grand Canyon is natural erosion feature) so the question for us is the human-induced rate of soil loss. Harper cites several studies that come to varying results, the worst suggesting that maybe a third of the naturally available top soil has been lost since agriculture began. But he also points out that we do not have reliable statistics on the amount of soil available and on it erosion. He also points out that despite some undeniable human-induced erosion, crop yields have increased over time as more technology has been invested in agricultural production (e.g., soil loss is over-ridden by technology, artificial fertilizers, and hybrids).

Modern, industrial agriculture is pretty hard on soils because it generally requires continuous cropping (rather than fallowing or multi-crop rotations), large and heavy machinery that affects soils structure, and use of pesticides that affect soil biota as well as targeted pests. Modern agriculture also replaces organic fertilizer and with fossil-fuel-derived synthetic fertilizers, in essence replacing natural fertility lost due to intensive cropping.

As mentioned above, the worst case assessment (by Southwick et al, a former CU prof) suggests a third of the world’s soil has been “lost” while a major assessment in 1990, the Global Assessment of Soil Degradation indicated that only a 10% of the earth’s vegetated surface had been ‘severely” degraded.

I mentioned in class studies by resources for the Future economist Pierre Crosson suggesting that current, human-enhanced rates of soil erosion in developed countries was about right given the economic benefits of agriculture and the costs of reducing soil erosion. We’ll return to such cost/benefit studies of resource proteciton when we talk about species loss.