Why You Should Give A Rip About Dirt
The literature and fine art of the ages whisper to us about the importance of the land. And in this century the motion picture industry has offered more on the subject. We've watched struggles over continents, countries, plantations, homesteads and even fields. Then a year or two ago Hollywood gave us a movie named "Waterworld":
Imagine an earth where global warming has melted the polar icecaps. For generations the planet has been covered by one big ocean. What's left of the human race is searching for a spot there have been rumors about. It's called dry land and some think it's a myth. There are villains, greasy sleazebuckets on corroded jet skis. There's a hero with an amazing low-tech sailboat and a chip on his shoulder the size of the Suez Canal--sort of James Bond and James Dean but with gills and webbed feet because, you see, evolution has been kick-started; he's a mutation. Until the hero shows up, the sleazebuckets can find no greater pleasure than ransacking isolated groups of good folks who live on rotting raft-forts where the most precious commodity isn't gold, silver or beluga caviar but ... little jars of dirt.
Okay, so "Waterworld" did a belly buster at the box office. But it brings up important questions. Are we taking something that is precious for granted? What would our lives be like without the thin skin that covers the land we live on?
Part of it is obvious. If we didn't have soil we wouldn't have wheat, cotton, trees and the other things that grow in it. How would we get a pizza, a pair of jeans or the kind of houses many of us live in? But as essential as food, clothing and shelter are, they aren't all we get from the soil.
Guess where researchers discovered some of our most important medicines? Yep. Because there are battles over resources down there, too. For eons bacteria that live around plant roots have been manufacturing what we now call antibiotics, like penicillin and streptomycin. They use them to defend themselves in life or death struggles with other bacteria that want the same turf. And there are other reasons we need that thin skin over the earth. For more on that, let's turn to some specialists.
Humans have worked with the soil, and pondered it, for thousands of years. These days we have professionals who dedicate their careers to studying it. We call them, simply, soil scientists. To prepare, they take courses in biology, chemistry, math, physics and lots of other disciplines. They've written volumes and volumes that explain why we should give a rip about dirt. Only they'd never use that vulgar, but common, term. Scientists much prefer that other four-letter word, soil.
An easy-to-read publication produced by soil scientists here in Oregon explains a lot about why soil is valuable. It's called the "Manual for Judging Oregon Soils." Oregon State University professors Herb Huddleston and Jerry Kling wrote it.
In its opening paragraph, the manual offers a fascinating, rather holistic thought from Nathaniel Shaler, a turn-of-the-century conservationist, about the importance of soil to all creatures great and small, not just humans. Soil, Shaler observed, is "a kind of placenta that enables living things to feed upon the earth."
"Unlike plant life," the manual goes on to explain, "we human beings can't manufacture our own food from the four primary resources of soil, air, water and sunlight. Instead, we depend completely on green plants, which take nutrients and water from soil and combine them with air and sunlight to provide our food supply.
"Some of those plants, such as wheat and corn, we eat directly. Others, such as alfalfa hay and range grasses, we process through livestock first. Even the fish we eat depend on plants that grow in the sea using nutrients that have been washed out of the soil and carried to the sea in rivers and streams."
Let's reconsider what the soil does, but in a more basic sense. It has several key functions in ecosystems, explains Benno Warkentin, an OSU soil scientist.
One example is storing things, such as water, carbon and other nutritious goodies needed by plants, animals and microorganisms. Soil is nature's time-release cold capsule. What if rain didn't penetrate into the ground and get trapped in little micro-reservoirs, called pores, which release it gradually to living things and into streams and groundwater? It would run off to the oceans. We could build more reservoirs. But we already have controversies over irrigation issues. Imagine if every day we had to get water back to all the places around the world it needs to be to quench the thirst of plants, animals and microorganisms? And the soil stores and releases chemicals and other nutrients in a similar, gradual way.
Another role soil plays in the ecosystem is as a temperature buffer, absorbing heat from the sun. This helps keep daytime temperatures from frying dogs, porcupines, apple trees and other living things. The soil releases this heat from the sun into the atmosphere gradually, making earth a much more hospitable place.
Another function of soil is what scientists call "biochemical and geochemical cycling." Basically, that's the way plants collect essential ingredients and use them to produce new growth. The plants "breathe" carbon and "exhale" oxygen that animals need. When life ends, soil is essential in the breakdown process, which releases the substances back into the ecosystem for another cycle.
This list of functions goes on. But you've probably gotten the idea that the earth wouldn't be worth much on the galactic real estate market if it didn't have a thin coating of soil. Now a little on how we got the coating:
In their manual, Huddleston and Kling define soil as "a living, dynamic system at the interface between air and rock. Soil forms in response to forces of climate and organisms that act on parent material in a specific landscape over a long period of time."
Making soil takes a whole lot longer than making chocolate chip cookies. The "parent material" is original geologic stuff like sandstone bedrock and, in much of Oregon, a volcanic rock called basalt. Other ingredients that go into soil, like volcanic ash, lake silt, dune sand and glacial gravels, are carried around by water, wind or ice.
Climate is an important part of the recipe, too--rain, heat and frost all help break down and change the parent material. In warm, moist climates like western Oregon, rocks and minerals break down rather quickly.
Three types of organisms are part of the recipe: large plants, animals and tiny plants (microbes). The roots of large plants help break rocks, and their channels provide pathways for water and air. Large burrowing animals, earthworms, insects and microscopic worms called nematodes help mix particles. Tiny plants (microbes) decompose organic matter, creating a complex black substance called humus that becomes the glue that holds the particles together in what we call soil.
The topography, or position of the land, also is important. Rain runs off hillsides, so they're dryer and soil forms slowly. But the water collects at the bottom of hillsides, taking with it particles and organisms that help soil form more quickly.
Last, making soil takes a long time. Many of Oregon's soils started forming during the ice ages and were placed where they are now, over thousands of years, by wind and water. It's almost beyond generations, in human terms--kind of the reverse of watching the light from stars that no longer exist. A rock, a lava flow or a wind-swept hill we see today may be the soil under children we can't even imagine.
Sitting atop a core of rock, the inner earth, Oregon's soil generally ranges from a depth of a few inches to 10 feet, but in some spots it's much, much deeper. Each region of the state has soils of various depths. Agricultural crops use only the top few feet (although the roots of wheat can go down 6 or 7 feet in deep soils, and the roots of a few trees such as juniper can go much deeper). The state has more than a thousand kinds of soils. Soil scientists have given them names. There's Willamette (one of the most productive soils in the state), Jory (the red soil in the Willamette Valley), Walla Walla (an important dryland soil of the Columbia Basin), Quincy (the wind-blown, sandy soil around Hermiston), and so on. Each has individual characteristics that influence human activities like agriculture and forestry, and characteristics that affect broader ecological functions related to issues like wetlands and waste disposal. Obviously, we won't be getting any new soil overnight, and that's a problem.
"There is worldwide concern about the progress of soil degradation," observes soil scientist Benno Warkentin.
Erosion is one of the major problems. The most common forms are where water or wind tear at the soil and carry it away. Some types of soils erode more easily. Soil that is disturbed is more vulnerable.
Compaction is another problem. You see this on school grounds where large numbers of people follow the same route. They cut a path where no grass grows. The still-barren ruts where the Oregon Trial ran are another example of compaction. Compacted soil has lost desirable structural properties, such as the right-sized pores for storing air and water. Heavy equipment, like the kind used in farming, logging and construction, can compact the soil, especially when it's wet.
Some soil is polluted from human-made or natural substances. Other soil is simply "tired." For example, the wrong kind of intensive gardening or farming can deplete the soil of key ingredients, or change its structure.
Another major obstacle, when it comes to the soil functioning as "a placenta that allows living things to feed upon the earth," is, simply, how we choose to use our land. Converting areas with rich soils "into urban housing, streets and roads is generally an irreversible process," notes Warkentin.
That's the bad news. The good news is that people across America are working to solve soil problems and preserve healthy soil. These range from farmers and foresters to the members of private conservation groups and employees in public agencies and institutions. Many OSU Agricultural Experiment Station and Extension Service personnel are working on this. An example is the research of Richard Dick:
When farmers have their soil analyzed, they usually check on how much fertilizer they need--substances such as nitrogen, phosphorus and potassium. But nutrients are just one part of healthy soil. Dick, an OSU soil scientist, and Marion County extension agent Dan McGrath and entomologist Andrew Moldenke are developing new ways to evaluate "tilth," or overall soil quality.
"We want to come up with standard ways of evaluating it--just like there are standard, multiple indicators of water or air quality," says Dick. Farmers, foresters and other land managers often know their land intimately and can evaluate their soil intuitively. This is what inspired the researchers.
"They [farmers] talk about the earthy smell of a good soil, or how they can go up a gear when they plow soil that is in good shape, or how water soaks in," says Dick. "We want to develop ways of measuring those intangible qualities and setting standards."
Thanks to Oregon vegetable farmers who volunteered their land, and the availability of land on OSU branch experiment stations, the researchers are studying properties of various soils in relation to crop types and growing practices. These practices include means of controlling erosion, such as planting cover crops that protect land during the off-season. Cooperating farmers use soil test kits to measure the qualities of their soil once a year.
Another relatively new area of research is looking at the soil as a habitat for biological processes and examining how this relates to crop production and other activities. According to OSU soil biologist Elaine Ingham, a spoonful of healthy agricultural soil contains 100 million or so bacteria and up to 500 feet of fungal strands, plus oodles of one-celled protozoa and microscopic nematodes and insects. Ingham and others are studying how these organisms interact in fertile and infertile soil.
For years OSU and other northwest Land Grant universities have combined forces with the U.S. Department of Agriculture's Agricultural Research Service, and with farmers and other citizens, in a federally funded project called STEEP. The acronym stands for "Solutions to Environmental and Economic Problems." The effort focuses scientists from many disciplines on projects aimed at conserving soil and water.
STEEP is a regional effort. Want a more cosmic example of research? OSU soil scientist Larry Boersma hopes to investigate the "global carbon cycle." You've probably heard of the "greenhouse effect," where many scientists think burning fossil fuels and other human activities are increasing the level of carbon dioxide in the atmosphere. A significant portion of the earth's carbon is stored in the soil. The OSU scientist plans to test his theory about how carbon moves through the soil into groundwater and eventually into streams and into the ocean, where it's released to the atmosphere. This has broad ecological implications.
Dan Sullivan, a soil specialist with the OSU Extension Service, is working to find opportunities to enrich the soil with non-toxic byproducts such as boiler ash, biosolids from municipal wastewater treatment and clarifiersludge from the pulp and paper industry.
OSU soil scientists such as researcher Neil Christensen and extension specialist John Hart are studying the most environmentally sound use of human-made and natural fertilizers. Other scientists, such as microbiologist Peter Bottomley, are studying organisms that have the ability to "fix" nitrogen around plant roots. Nitrogen-fixing bacteria can whip up a nutritious fertilizer for plants out of a form of nitrogen the plants couldn't use otherwise.
In the dryland agricultural region of eastern Oregon many fields have developed hardpans. Sometimes during winter storms, rainfall can't fully enter this compacted layer of soil. This can result in the loss of valuable top soil from erosion. An OSU soil geochemist, John Baham, is investigating how these hardpans form and what can be done to reduce their severity.
These are a few examples of work going on around Oregon. In general the profile of soil scientists, under-appreciated a decade ago outside agricultural circles, is rising. OSU's Department of Crop and Soil Science recently set up a new program in what it calls "environmental soil science." The goal is to prepare students for work in waste management, environmental impact assessment, wetlands and water quality work, land evaluation and other soil-related areas.
"I can tell you about the motion of the stars, but not about the soil under my foot," Leonardo da Vinci observed during the Renaissance. These days we're learning more about the soil under our feet, enough to know we'd better take very good care of the limited supply we have.
The "Manual for Judging Oregon Soils" puts it like this: "If we manage our soil properly it will continue to nourish us for generations to come. If we don't, our very civilization is threatened."