Illinois
Fertilizer Conference Proceedings
January 24-26, 1994
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Ted R. Peck and Marilyn E. Sullivan1
Electro-Ultra-Filtration (EUF) is a three cell apparatus (1). The middle cell contains the soil suspension being tested (soil:water of 1:10) with a stirrer, water inflow, and temperature regulation. Each side of the middle cell is a cell provided with a micropore filter attached to electrodes with the anode on one side and the cathode on the other. The cations accumulating at the cathode and the anions at the anode are continuously flushed to collecting tanks by a stream of water. The first 6 fractions are collected at room temperature and a voltage of 200. Fractions 7 and 8 are collected at 80° C and 400 volts. Increasing the voltage can result in characterizing nutrient amounts held at different bonding energies.
The study utilizes pre-existing land areas devoted to. K rate build-up since 1966 at the Brownstown Research Center, since 1967 at Northern Illinois Research Center, and since 1970 at the Agronomy/Plant Pathology South Farm, Urbana, IL.
EUF extractable potassium from soil with different K fertilization histories are shown in figures 1, 2, 3, and 4. The conventional K soil test levels of soils used in Figure 1 are CK=264, 50=320, 100=352, 150=416, 200=488, and 250=4721bs/a K, respectively. The cumulative K extracted in the first 6 fractions is CK=270, 50=297, 100=439, 150=390, 200=500, and 250=471 lbs/a K. The total K extracted in all fractions is CK=450, 50=452, 100=730, 150=662, 250=844, and 250=816 lbs/a, respectively.
Figure 2 shows the extraction of K by EUF with all fractions at room temperature (25° C), fractions 1 through 6 at 200 volts and fractions 7 and 8 at 400 volts. These extractions differ from figure 1 in that in figure 1, fractions 7 and 8 are at 80° C.
Figure 3 shows EUF extractable K of soil samples collected from the field on April 30, 1993. The conventional K soil test levels of these soil samples are CK=208, 50=280, 100=312, 150=384, 200=368, and 250=408, respectively. Total EUF-K extracted in all fractions is CK=226, 50=304, 100=336, 150=397, 200=476, and 250=521, respectively.
Figure 4 shows EUF extractable K of soil samples collected from the field on April 30, 1993 in the field moist condition (22-23 % moisture by weight). The conventional K soil test level of these soil samples are CK=135, 50=168, 100=227, 150=305, 200=324, and 250=352, respectively. Total EUF-K extracted in all fractions is CK=140, 50=122, 100=233, 150=313, 200=428, and 250=486, respectively.
Soil K levels of soil samples differ depending on date of field soil sampling
and moisture level of the soil at time of extraction. There is a correlation
of test level and field K treatment history and method of testing.
Figure 1. Air Dry Soil Samples 2-15-93 (at 80° C)
Figure 2. Air Dry Soil Samples 2-15-93 (at room temperature)
Figure 3. Air Dry Soil Samples 4-30-93
Figure 4. Field Moist Soil Samples 4-30-93
1 Ted R. Peck is Professor and Marilyn Sullivan is Research Specialist, Dept. of Agronomy, Univ. of IL.
