The method used consisted of collecting soil samples of varying organic matter levels and subject those samples to three different moisture levels: oven-dry, 1/3 BAR, and 15 BAR. At each moisture level the spectral response was measured with a field spectroradiometer (Exotech 20C) under simulated solar radiation. The data was then analyzed and interpreted by the investigators.
The sample number stored in the SCENE TYPE indicates the soil series name and the soil moisture tension (see Table 1). The sample letter in the SCENE TYPE indicates the replication. The replications are A, B, C, D, and E. The oven dry samples for replication A are the same samples as those used for the 1/3 bar set for replication A, ... same is true for B, C, D, and E.
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Table 1. Correlation of Soil Series Name, Sample Number,
and Soil Moisture Tension.
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Soil Series Name 1/3 Bar 15 Bar Oven Dry
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Brookston 1 16 31
Chalmers 2 17 32
Corwin 3 18 33
Crosby 4 19 34
Dana 5 20 35
Delmar 6 21 36
Fincastle 7 22 37
Kokomo 8 23 38
Miami 9 24 39
Odell 10 25 40
Parr 11 26 41
Raub 12 27 42
Romney 13 28 43
Russell 14 29 44
Sidell 15 30 45
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Organic Carbon by the Allison Method. Soil that has passed .149 mm sieve was used for organic carbon measurement. Sample holders were 4 inches in diameter. Samples were 1-2 cm thick.
There is justification for this approach based upon attempts being made to use multispectral imagery to assist in the mapping of soils especially by the Soil Conservation Service Soil Survey Methods. (7,8,9,10) It has been found that as the distance from the soil test areas used as training samples increased, the accuracy of the soils identified by the computer decreased, thus limiting the usefulness of multispectral imagery for assisting in soil mapping (10). One of the major factors which adds to this problem may be due to differences in soil moisture and its relationship with organic matter.
The area of study is known as flightline 210 taken during the 1971 Southern Corn Leaf Blight Experiment which lies approximately 1/2 mile either side of the Warren County-Tippecanoe County line from Otterbein, Indiana to the Wabash River. This flightline includes a segment of the area known by ecologists as the eastern tip of the Prairie Peninsula. This Prairie Peninsula contains soils developed under the tall grass prairie environment, Udolls, and is surrounded by the soils developed under the hardwood forest environment, Udalfs.
Four soil catenas will be studied, two prairie catenas and two forest catenas, and shall serve as the variation in soil organic matter. The spectral characteristics at three moisture contents, oven dried, 15 BAR and 1/3 BAR, will be measured with the Field Spectroradiometer under solar radiation.
2. 4 inch diameter cores 1 inch thick will be taken in cultivated fields and subjected to 3 moisture treatments: oven-try, 15 BAR and 1/3 BAR.
3. 4 such cores will be taken at each site, three will be subjected to the moisture treatments and one will be used to test for organic matter, texture, type of clays, oxidized and reduced iron compounds, etc.
4. 15 soils will be tested.
Loess over Loam Till Loam Till
Drainage Prairie Forest Prairie Forest
Well Sidell Russell Parr Miami
Mod. Well Dana Corwin
Somewhat poorly Raub Fincastle Odell Crosby
Poorly Delmar
Very poorly Chalmers Brookston Chalmers Brookston
Very poorly Romney Kokomo Romney Kokomo
5. The samples will then be measured with the field spectroradiometer with solar radiation with 3 reps, one taken each of three different days. This will mean a total of 135 readings, 45 per day for each 3 different days.
6. The field radiometer will measure radiation in a spectral range from 400 to 2400 nanometers (nm).
Literature Cited
1. Al-Abbas, A. H., P. H. Swain and M. F. Baumgardner. 1971. Relating Organic Matter and Clay Content to the Multispectral Radiance of Soils. Journal Paper No. 4549, Purdue University Agricultural Experiment Station.
2. Baumgardner, M. F., and S. K. Kristof, C. J. Johannsen and A. L. Zachary. 1970. Effects of Organic Matter on the Multispectral Properties of Soils. Journal Paper No. 3939, Purdue University Agricultural Experiment Station.
3. Bowers, S. a. and R. H. Hanks. 1964. Reflection of Radiant Energy from Soils. Soil Science 100:130-138.
4. Cipra, J. E., M. F. Baumgardner, E. R. Stoner, and R. B. MacDonald. 1971. Measuring Radiance Characteristics of Soil with a Field Spectroradiometer. Soil Sci. Soc. Amer. Proc. 35:1014-1017.
5. Condit, H. R. 1970. The Spectral Reflectance of American Soils. Photogammetric Engineering. 36:955-966.
6. Hoffer, R. M. and F. E. Goodorick. 1971. DR-2 Multiple Spectral Plotting. Laboratory for Applications of Remote Sensing Information Note 021671. Purdue University.
7. Kristof, Steven J. 1971. Preliminary Multispectral Studies of Soils. Journal Soil and Water Cons. 26:15-18.
8. Mathews, H. L., and R. L. Cunningham, J. E. Cipra and T. R. West. 1973. Application of Multispectral Remote Sensing to Soil Survey Research in Southeastern Pennsylvania. Soil Sci. Soc. Amer. Proc. 37:88-93.
9. West, T. R. 1972. Engineering Soils Mapping in Indiana by Computer from Remote Sensing Data. Proc. Indiana Academy of Science. 81:210-216.
10. Zachary, A. L., J. E. Cipra, R. I. Diderickson, S. J. Kristof and M. F. Baumgardner. 1972. Application of Multispectral Remote Sensing to Soil Survey Research in Indiana. Laboratory for Application of Remote Sensing Print 110972. Purdue University.