Moisture Conservation in Relation to Erosion Control Under Red Plains Conditions in the Southwest

The Red Plains Soil Erosion Experiment Station Is located about 4-1/2 mllea south of Guthrie, Oklahoma, near the center of the State and In the heart of the Red Plains Region, which comprises about 36,000,000 acres In Central Oklahoma, the North Central part of Texas and a border, of south Central Kansas. The soils are residual from the underlying red and gray sandstones and shales. The Vernon soil series predominates and are found on the rolling to broken topography, while the Kirkland, Foard and Marshall series occur on the smoother divides and ridge crests. The Kirkland, Foard and Marshall soils were developed under prairie conditions and supported a growth of blue-atem and buffalo grasses, while much of the Vernon soil supports a scant growth of blackjack and post oaks with mesquite and chaparral in Texas, along with native grasses. The Klrkland soils are deeper and have rather compact semi-impervious clay to sandy clay subsoil, while the subsoil material of the Vernon series is more friable sandy clay with underlying parent material usually occuring at 3 to 6 feet below the surface. The Vernon soils predominate with a small amount of Kirkland on the Experiment Station, and as a whole the soils are neutral to slightly acid in the surface. There is very little Increase of lime content with depth in the Vernon soils, however in the Kirkland soils there is an increase of free lime carbonates. The Red Plains Station was established in 1929 and the work carried on is cooperative between the Bureau of Chemistry and Soils and the Bureau of Agricultural Engineering of the U. S. Department of Agriculture; the Oklahoma Experiment Station and the Guthrie Chamber ofCommerce of Guthrie, Oklahoma. Approximately 70 acres of the original farm, which comprises 160 acres, had been under cultivation for a 40-year period from 1889, when this section of Oklahoma was opened for settlement, until 1929. The remainder of the farm was used for pasture and much of it supported a growth of oak. Of the cultivated portion, an erosion survey, which was made at this time, showed that this land had lost about 1900 tons of soil per acre for the 40-year period or an average of about 48 tons per acre per year. Much of the land that had been under cultivation for this period was so badly eroded and gullied that only small patches were being farmed, in fact the land was ready to be abandoned for crop production due to the ravages of erosion. During 1932, a farm of 110 acres, 65 acres of which had been abandoned due to erosion, and Just east of the main station, was taken over where gully control, grass and forest studies are being conducted. The averpge rainfall for the Red Plains Region at Guthrie, Oklahoma, for the period 1893 to 1930, inclusive, is 32.72 inches per year, the larger part of which falls during the early spring and fall months, while the summer months as a rule are hot and dry. Rainfall Intensities of 2 to 3 Inches per hour are common, and an intensity of .about 5.00 inches per hour has been recorded for a 15 minute period and on September 29, 1934, an intensity of 3.00 inches per hour was recorded for a 20 minute period. The soils of the region are very susceptible to erosion and it is during rains of these high Intensities when run-off and soil losses are greatest. Many methods of Erosion Control are being used, consisting of: Crop rotation; Contour farming; Terracing; Leguminous and non-leguminous cover crops; Strip cropping alone, also in conjunction with terraces, as well as gully control by means of simple inexpensive mechanical dams in conjunction with vegetative cover of grass and trees. Studies in connection with different grasses suited for this region; Effects of burning over forest land as compared to unburned land on run-off and soil losses; Fertility work in connection with cotton; Rebuilding fertility of badly eroded land by different treatments; Effect of direction of rows on run-off and soil losses; Effects of subsoiling on crop yields; Different tillage methods, such as the use of hole-digging machine as compared to ordinary flat cultivation, and soil moisture under different crops, Cover and mechanical conditions. Each of these studies constitute a very dlfinite part of our work in connection with Erosion Control methods. There does not seem to be any one of these methods which solves the problem of run-off and soil loss entirely, however a combination of a number of the best known methods will go a long way toward saving much of the run-off water which Is badly needed to be conserved for crop growth during the growing season. In checking the run-off water soil losses are also retarded. As stated in the first part of this paper, most of our precipitation comes in the early spring and fall months and the summer months as a rule are hot and dry, with very light rainfall. During 1933, from May 26th to July 13th, a period of 49 days, there was only .07 inches of rainfall. During 1934, from June 17th to August 21st, a period of 66 days, there was only .12 inches of rainfall in 3 separate showers, practically all of which was lost by evaporation. All crops suffered for lack of moisture. During 1934, until June 16th, there had been a total of 13.08 Inches of precipitation and there was considerable soil moisture under most all crop conditions. Crops had started off well, but during the latter part of June, all of July and the first part of August, the weather was very hot and dry, the average maximum temperature for Oklahoma being 102.9° for the month of July. On August 22 and 23 there was a heavy rain of 5.76 inches; 3.42 inches falling In 137 minutes, or at the rate of 1.60 inches per hour, causing run-off. On August 25 another rain of 1.09 Inches fell, making a total of 6.85 Inches In the last few days in August. During September there was 9.41 Inches and .02 inches up to October 15, 1934. Evaporation is quite high during the hot, dry spells and small showers which occur are largely lost by evaporation and are of little or no benefit for crop growth. During the last 6