Botany 3214 - Soils

1. Botany 3214 - Soils SOILS ASSOCIATED WITH AGRICULTURE

2. Agriculture began some 7000 years ago in Mesopotamia • Mesopotamia (the Sumarian) irrigation systems dates back to 3500 B.C. • 1000 years ago Phoenicians cut the Lebanon cedar forest for King Solomon’s temple, resulting in ruin of the forest, erosion occurred leaving a denuded and rocky barren.

3. Hammurabi of Babylon, 1800th century B.C., described brick lined canals having asphalt mortar and an irrigation system compassing 25,900 km2 (Iraq) supporting 15 to 20 million people. The same area today only supports one-fourth that number.

4. Siltation was a blessing for those (flourishing civilizations) who lived along the Nile of Egypt. Helped rejuvenate the soil due to erosion from above. Worked really well until dams were built along the Nile which prevented flooding (siltation).

5. Nile farmers hitched a hoe to an ox and invented the plow some 6000 years ago. Hence, the process of preparing the ground did not require as many men. Therefore, they could be released to help build the pyramids.

6. China’s once deep, fertile soils of the north eroded away at an alarming rate along the Yellow River (known as China’s Sorrow). This erosion has resulted in the change of the river course many times. Today the Yellow River has been diked at a dangerously high level above the flood plain. When it floods, thousands of people are endangered. This has been going on in China for the last 4000 years.

7. Western Civilization • Incas of Peru (Machu Picchu) was extensively terraced and contained waterways cut in rock. The steep sloped mountain tops had no soil, so terracing was necessary. The soil to fill the terraces had to be brought up from the valley.

8. North America • One half of the original Midwest topsoil has eroded away in the past 150 years. • Drought, a common association of farming, has occurred roughly at 22-year intervals. Drought in the great plains occurred in 1890, again in 1910 and again from 1927 to 1932. Grass withered and died, overgrazed pasture was clipped to the roots by scrawny cattle that were mercifully slaughtered.

9. Drought and wind had both visited the great plains but never as it occurred during these years. Overgrazing (compaction and consumption of grasses), continued farming exposing the bare soil to the elements, no recycling of organic matter, hence, no soil buildup led to the devastation of the “black blizzard.”

10. 1934 and 1935 brought winds of gale forces, swept over the great plains (Kansas, Oklahoma, Texas, Colorado, and Nebraska. Wind hurled the clay and silts thousands of feet into the air forming brown clouds, 2,000 to 3.3 kilometers high.

11. May 11, 1934 a storm lifted 300 million tons of soil into the air (equal to the total amount of soil scooped out of the earth) forming the Panama Canal. • March and April 1935 Amarillo, Texas had 15 wind storms that lasted 24 hours with four lasting 55 hours.

12. Oklahoma dust was rested on the deck of an ocean steamer 330 kilometer out to sea. Dust sifted into offices on Wall Street, smudged luxury apartments on Park Avenue. When it rained the drops would come down as diluted mud. Cars had to pull off the highways, ranchers got lost in their own backyards, dust sifted into homes covering everything, airplanes were grounded, trains were stalled by huge drifts, nurses placed wet cloths over the mouth of patients, some relief workers contracted “dust pneumonia” four of who died.

13. Jokes were told of birds flying backwards to keep the dust out of their eyes, prairie dogs were said to have dug burrows 100 feet in the soil. • 300 million tons of top soil were eroded away in one single storm May 22, 1934, equivalent to taking 3,000 farms of 100 acres each out of production

14. The cost was staggering; 1 billion in relief, 7 million in a single county in Colorado • Their land gone, penniless they had to find a new way of life. They piled their belongings into their rickety old cars and trucks and headed to the industrial cities of the Midwest as California. Because of the depression they were treated as convicts and struggled severely

15. Route 66 became famous along with John Steinbeck’s book “Grapes of Wrath.” • 1947 Pioneers into the Salt Lake valley. Dug canals, plowed and planted.

16. RESULTS OF THE DUST BOWL: • Shelter belts • Series of trees at right angles to the prevailing winds. • Deciduous verses evergreen • 1935, 218 million trees planted on 30,000 farms from South Dakota to Texas. • 32,000 kilometer of trees

17. 1 to 5 rows of trees • 30 mph >> 21 mph>>shelter belt >8 mph 200 ft 100 ft 100 ft >>10 mph>>14 mph>>15 mph>>21mph>> 200 ft 300 ft 400 ft 500 ft >>30mph >>1500ft

19. Wind breaks do the following: • Wind break • Aesthetics • Increase soil moisture by decreasing evaporation • Trapping winter storms • Habitat for wildlife

20. 25 % of the 1935 shelter belts have been removed to: • Provide fuel • Increase acreage for crop production • Facilitate irrigation • Use of heavy machinery

21. SOIL EROSION TODAY: • 1933 - Soil Erosion Control Service = Soil Conservation Service = Natural Resource Conservation Service • Black Blizzards (dust storms) still with us.

22. 1977 San Joaquin Valley, CA - 20 mil tons of soil lost by wind on 880 sq miles grazing land in 24 hours - winds exceeded 100 mph • .Severe drought • .Wind 10 mph • .Lack of wind breaks • .Just plowed land for planting • .Urban expansion\ • ORV and Motor cycles

23. Plow-outs (sod busting) conversion of non-farm to farm land. • Mostly in the Midwest - Western Great Plains results in 3 to 5 years financial gain then loss of fertility, erosion and possible never recover. • Montana and Colorado have passed laws to prevent sod busting • Today, erosion is sharply reducing production at a time when the world population demands more. • 1935-1965 crop production increased at the rate of 2.1% • 1965 until now, production has increased at only 1.7%

24. Some wheat growing areas have been so severely eroded that their productivity will may be over by the year 2000. • Eastern Washington - 1 kiolgram of wheat for 20 kilograms of soil lost to erosion. • Iowa and Illinois - 1 bu wheat per 2 bu soil lost - nutrient compensation for the erosion loss would cost 1.6 billion for fertilizer.

25. U.S. TOPSOIL: • A few centimeters to 1 meter thick • Thick layer of topsoil can withstand a loss of 5 tons per acre per year - not change soil fertility and productivity compensated for by equal or greater soil formation. some suggest that this is too much loss.

26. Soil Conservation Service (SCS) suggest that erosion in the U.S. is 7 times greater than natural rate of formation. • Surveys suggest that erosion exceeds soil building. • Another survey suggests that erosion exceeds on 44% of the land in America.

27. Farming in Washington, Oregon, and Idaho on steep slopes lose 120 to 250 metric tons per year. • 1977 Soil and Water Resource Conservation Act - USDA charged with making a comprehensive appraisal of the quantity and quality of U.S. soil reserves. • Soils differ greatly in erodibility - some eroding 1000 times faster than others.

28. FACTORS AFFECTING RATE OF EROSION: • 1. Precipitation - ranges in U.S. from almost 0 in Death Valley to 140 inches in parts of Washington State. • An area in Texas received 25 inches in 24 hours last week. Results were severe erosion. • Areas in Nevada and Arizona where rainfall is 5 inches per year - erosion is severe because annual precipitation occurs in torrential cloudbursts.

29. Soil Structure - green manure and the addition of organic matter greatly improves the soils water holding capacity. Grass and their fibrous root systems bind and hold the soil. • Topography - 10% slope is one that drops 10 meters over a horizontal distance of 100 meters. Doubling the slope triples the soil erosion by water.

30. Soil Structure - green manure and the addition of organic matter greatly improves the soils water holding capacity. Grass and their fibrous root systems bind and hold the soil. • Topography - 10% slope is one that drops 10 meters over a horizontal distance of 100 meters. Doubling the slope triples the soil erosion by water.

31. SOIL EROSION CONTROL PRACTICES: 1. Contour Farming • European farmers plowed up and down the hills. • Thomas Jefferson said, “we now plow horizontally, following the curvature of the hills...scarcely an ounce of soil is now carried off.”

34. Texas experiment with a farm of 3-5% slope showed a loss of 4.6 inches of water runoff on a non-contoured plot verses 1.6 inches on a contour farmed plot. 2. Strip Cropping

37. 3. Terracing - to be effective, must stop water from attaining a velocity of 1 meter per second so that it doesn’t loosen and transport soil. Twotypes of terracing: Broad base terrace - farming over whole terrace may be built on slopes up to 8% Grass based terrace - slope greater than 8% but not farmed over whole terrace • Keep the soil covered

40. 4. Gully Reclamation Check dams - cover crops anything to hold the soil in place.

43. 5. Removing Cropland from Production – • 1985 Food Security Act. • Removal of 45 million acres of marginal, highly erodable land - stops the erosion, provides habitat and stabilizes the soil. • Farmer makes a contract with the USDA to withdraw the land from cropping for 10 years and establishes vegetation to stabilize the soil.

44. USDA rents the acreage at $42.00 per acre per year. • 1990 only 35 million acres had been taken out of productivity. • Resulted in annual erosion stoppage of 500 million metric ton/year. • Established other incentives allowing the 1.5 million farmers who enrolled to be eligible for federal crop insurance, subsidies, and other benefits.

45. 6. Conservation Tillage Plowing, one or two passes for harrowing, planting, and cultivating at least once. At least 5 passes over the land. 30% of the farmers are doing this now No till - 75% of previous crops residue is still on the land, crops are planted directly into the rubble

48. Keep ground covered reducing erosion up to 90%

49. PROS AND CONS OF NO-TILLING FARMING: • Pros: • 1. Labor may be reduced by 30 to 50%. The only pass over the field is for planting and fertilizing, pesticide application and harvesting. • 2.Use of diesel fuel is reduced by 30 to 50%.

50. 3.Wear and tear of farm equipment is reduced. 4. Soil erosion is generally reduced by 90%. 5. Soils retain more moisture because of reduction rates of evaporation and surface runoff.