Table 1. Location of research sites and Sharkey unit.
Site Location Soil Mapping Unit
1 Percy Quinn State Park Sharkey clay, level phase, 0 to ½% slopes
2 Percy Quinn State Park Sharkey clay, nearly level phase, ½ to 2% slopes
3 Delta Experimental Forest Sharkey clay, level phase, 0 to ½% slopes
4 Delta Experimental Forest Sharkey clay, nearly level phase, ½ to 2% slopes

Table 2. Pedon description Site 1, Leroy Percy State Park, Washington County, MS.
  (moist colors)
A 0 to 5 inches; very dark grayish-brown (10YR 3/2) clay; moderate medium angular blocky structure; friable; many fine, medium, and coarse roots; cracks 1 to 2 inches wide; very strongly acid; clear wavy boundary.
Bg1 5 to 13 inches; dark gray (10YR 4/1) clay with common fine distinct strong brown (7.5YR 5/8) mottles; moderate medium angular blocky structure; firm; very sticky, very plastic; common fine and medium roots; pockets and cracks 0.50 to 0.75 inch wide; very strongly acid; gradual wavy boundary.
Bg2 13 to 22 inches; dark gray (10YR 4/1) clay with common fine faint light brownish-gray (10YR 6/2) and common fine distinct strong brown (7.5YR 5/8) mottles; weak medium angular blocky structure; firm; very sticky, very plastic; common pressure faces on ped exteriors and few small slickensides; common fine roots; pockets and cracks 0.50 inch wide; strongly acid; gradual wavy boundary.
Bssg 22 to 50 inches; dark gray (10YR 4/1) clay with common fine and medium distinct yellowish-brown (7.5YR 5/6) mottles; weak coarse prismatic parting to weak medium angular blocky structure; firm; very sticky, very plastic; few fine roots; common coarse intersecting slickensides; neutral; gradual wavy boundary.
Bssyg1 50 to 65 inches; gray (10YR 5/1) clay with many medium distinct strong brown (7.5YR 5/8) and brown (10YR 5/3) mottles; weak coarse prismatic parting to weak medium angular blocky structure; firm; very sticky, very plastic; common fine, medium, and coarse white (10YR 8/1) gypsum crystals in veins; common medium round iron-manganese concretions; mildly alkaline; gradual wavy boundary.
Bssyg2 65 to 90 inches; gray (10YR 5/1) clay with common fine distinct strong brown (7.5YR 5/6) mottles; weak coarse prismatic parting to weak fine subangular blocky structure; firm; very sticky, very plastic; common gypsum crystals; few fine black concretions; few fine roots; common coarse grooved slickensides that intersect; mildly alkaline; gradual wavy boundary.
C1 90 to 110 inches; light brownish gray (10YR 6/2) clay with many medium distinct strong brown (7.5YR 5/6) and few fine distinct yellowish-red (5YR 5/8) mottles; weak fine subangular structure; firm; sticky, plastic; few fine black concretions; moderately alkaline; gradual, wavy boundary.
2C1 110 to 120 inches; grayish-brown (10YR 5/2) clay loam with many moderate distinct strong brown (7.5YR 5/6) and few fine distinct red (5YR 5/8) mottles; weak fine subangular blocky structure; firm; few fine and medium black concretions; mildly alkaline; abrupt, smooth boundary.
2C2 120 to 130 inches; yellowish-red (5YR 5/6) clay loam with thin reddish-brown (5YR 5/3) seams; massive in place, parting to weak fine subangular blocky structure; firm; few fine soft black concretions; mildly alkaline.

Table 3. Pedon description Site 2, Leroy Percy State Park, Washington County, MS.
  (moist colors)
A 0 to 4 inches; very dark grayish-brown (10YR 3/2) clay; moderate medium angular blocky structure; firm; sticky, plastic; many fine, medium and coarse roots; cracks 1 to 2 inches wide; pressure faces on ped exteriors; slightly acid; gradual wavy boundary.
Bg1 4 to 12 inches; very dark grayish-brown (10YR 3/2) clay with common fine distinct strong brown (7.5YR 5/6) and few fine distinct yellowish-red (5YR 5/8) mottles; weak coarse prismatic parting to moderate medium angular blocky structure; firm; very sticky, very plastic; common fine and medium roots; cracks 0.5 to 1 inch wide; few slickensides; medium acid; gradual wavy boundary.
Bssg 12 to 18 inches; dark gray (10YR 4/1) clay with common fine distinct strong brown (7.5YR 4/6) mottles; weak coarse prismatic parting to moderate medium angular blocky structure; firm; sticky, plastic; common medium roots; cracks 0.5 to 0.25 inch wide; common coarse intersecting slickensides; medium acid; gradual wavy boundary.
Bg2 18 to 29 inches; dark gray (10YR 4/1) silty clay loam with common fine distinct strong brown (7.5YR 5/8) mottles; weak fine subangular blocky structure; firm; few fine roots; pressure faces on ped exteriors; slightly acid; gradual wavy boundary.
Bg3 29 to 36 inches; dark grayish-brown (10YR 4/2) clay loam with common fine distinct strong brown (7.5YR 5/8) mottles; weak fine subangular blocky structure; firm; slightly acid; gradual wavy boundary.
2C1 36 to 50 inches; pale brown (10YR 6/3) loam with common fine and medium distinct strong brown (7.5 YR 5/8) and few fine faint grayish-brown (10YR 5/2) mottles; massive; firm; neutral; gradual wavy boundary.
2C2 50 to 65 inches; grayish brown (10YR 5/2) loam with few fine distinct brownish-yellow (10YR 6/8) mottles; massive; firm; mildly alkaline.

Table 4. Pedon description Site 3, Delta Experimental Forest, Washington County, MS.
  (moist colors)
A 0 to 5 inches; very dark grayish-brown (10YR 3/2) clay; moderate medium angular blocky structure; friable; many fine, medium, and coarse roots; cracks 1 to 1.5 inches wide; very strongly acid; gradual wavy boundary.
Bg1 5 to 9 inches; dark gray (10YR 4/1) clay with many fine and medium distinct strong brown (7.5YR 5/8) mottles; moderate medium angular blocky structure; firm; very sticky, very plastic; common fine and medium roots; pockets and cracks 0.25 to 0.50 inch wide; strongly acid.
Bg2 9 to 19 inches; dark gray (10YR 4/1) clay with many fine and medium strong brown (7.5YR 5/8) mottles; weak coarse prismatic parting to moderate medium angular blocky structure; firm; very sticky and plastic; common fine and medium roots; pockets and cracks 0.25 inch wide; many pressure faces on ped exteriors; strongly acid; gradual wavy boundary.
Bssg 19 to 40 inches; dark gray (10YR 4/1) clay with many fine and medium distinct brown (7.5YR 4/4) mottles in the upper part and common fine distinct brown (7.5YR 4/4) mottles in the lower part of horizon; weak coarse prismatic parting to weak medium angular blocky structure; firm; very sticky and plastic; common coarse intersecting slickensides; few fine and medium roots; many firm, black round concretions ranging 2 to 4 mm diameter; medium acid; gradual wavy boundary.
Bssyg 40 to 60 inches; grayish-brown (10YR 5/2) clay with many medium distinct brownish-yellow (10YR 6/8) mottles; weak coarse prismatic parting to weak medium angular blocky structure; firm; very sticky and plastic; common tongue and grooved intersecting slickensides; many white (10YR 8/1) gypsum crystals ranging to 4 mm diameter in veins and pockets; neutral; gradual wavy boundary.
By 60 to 70 inches; mottled brownish-yellow (10YR 6/8), strong brown (7.5YR 5/8), and pale brown (10YR 6/3) clay; massive; firm; very sticky and plastic; common pressure faces on ped exteriors; common white (10YR 8/1) gypsum crystals; mildly alkaline.
C1 70 to 80 inches; brownish-yellow (10YR 6/8) clay loam with many medium distinct brown (10YR 5/3) mottles; massive; firm; few white (10YR 8/1) gypsum crystals; mildly alkaline.
C2 80 to 90 inches; brownish-yellow (10YR 6/8) clay loam with many medium distinct brown (10YR 5/3) and few fine faint pale brown (10YR 6/3) mottles; massive; firm; common soft black concretions; mildly alkaline.
C3 90 to 100 inches; yellowish-brown (10YR 5/8, 5/4) loam with common medium faint brown (10YR 5/8, 5/4) mottles; mildly alkaline.
C4 100 to 110 inches; yellowish-brown (10YR 5/6) sandy loam; massive; firm; mildly alkaline.
C5 110 to 120 inches; brownish-yellow (10YR 6/6) silt loam; massive; firm; mildly alkaline.
Sampled below 90 inches by auger.

Table 5. Pedon description Site 4, Delta Experimental Forest, Washington County, MS.
  (moist colors)
A 0 to 6 inches; dark grayish-brown (10YR 4/2) clay; moderate medium angular blocky structure; friable; many fine and medium roots; cracks 0.5 to 1.5 inches wide; strongly acid; clear smooth boundary.
Bg1 6 to 12 inches; dark gray (10YR 4/1) clay; slightly firm; very sticky and plastic; few medium roots; few black concretions; pockets and cracks 0.5 to 1 inch wide; very strongly acid; clear smooth boundary.
Bg2 12 to 23 inches; dark gray (10YR 4/1) clay with many medium distinct strong brown (7.5YR 4/6) mottles; moderate fine and medium angular blocky structure; firm; very sticky and plastic; few coarse, common fine and medium roots; pressure faces on ped exteriors; strongly acid; gradual wavy boundary.
Bssg1 23 to 31 inches; dark gray (10YR 4/1) clay with many medium distinct strong brown (7.5YR 4/6) mottles; weak coarse prismatic parting to weak medium angular blocky structure; firm; very sticky and plastic; common coarse, grooved slickensides; few fine and medium roots; strongly acid; gradual wavy boundary.
Bssg2 31 to 50 inches; gray (10YR 5/1) clay with many medium distinct strong brown (7.5YR 5/8) and few medium faint dark yellowish-brown (10YR 4/6) mottles; weak coarse prismatic parting to weak medium angular blocky structure; firm; very sticky and plastic; many coarse tongue and groove intersecting slickensides; few, hard round black concretions; slightly acid; gradual wavy boundary.
Bssyg 50 to 67 inches; grayish-brown (10YR 5/2) clay with many medium distinct strong brown (7.5YR 5/8) and common medium yellowish-brown (10YR 4/6) mottles; weak coarse prismatic parting to weak medium angular blocky structures; firm; very sticky and plastic; many coarse, tongue and groove intersecting slickensides; many white (10YR 8/1) gypsum crystals; neutral.

Table 6. Soil bulk density of selected depths at field moisture percentage indicated in parentheses.
Depth Site
1 2 3 4
Inches ----------g cm-3----------
0-6 0.89 (50)* 0.77 (51)* 1.01 (50)* 0.85 (47)*
6-12 1.11 (48) 1.20 (37) 1.03 (51) 1.08 (50)
12-18 1.16 (46) 1.20 (43) 1.01 (53) 1.15 (42)
18-24 1.18 (40) 1.40 (29) 1.24 (38) 1.29 (37)
*Contained dense root mat

Table 7. Soil moisture retention of selected depths of Sharkey research sites.
Depth 0.03 0.1 0.3 0.6 1.5 Available H2O
Inches ----------MPa---------- % (Weight)
Site 1 
0-6
 
51.9
 
48.4
 
47.2
 
43.2
 
41.7
 
10.2
 
6-12
 
50.5
 
48.7
 
46.5
 
43.0
 
41.3
 
 9.2
 
16-22
 
51.4
 
49.2
 
47.5
 
44.0
 
42.1
 
 9.3
 
30-36
 
47.6
 
45.9
 
44.8
 
41.9
 
40.2
 
 7.4
Site 2 
0-6
 
51.3
 
48.1
 
46.5
 
42.7
 
40.9
 
10.4
 
10-16
 
43.3
 
41.1
 
39.5
 
36.7
 
35.1
 
 8.2
 
22-28
 
46.6
 
44.7
 
43.0
 
40.0
 
38.3
 
 8.3
 
30-36
 
28.8
 
26.7
 
25.1
 
22.7
 
22.0
 
 6.8
Site 3 
0-6
 
51.8
 
48.4
 
46.3
 
42.2
 
40.6
 
11.2
 
6-12
 
54.3
 
51.6
 
49.2
 
44.7
 
42.5
 
11.8
 
12-18
 
55.3
 
52.1
 
50.2
 
46.3
 
44.5
 
10.8
 
18-24
 
50.3
 
47.8
 
46.5
 
43.1
 
41.0
 
 9.3
Site 4 
0-6
 
52.1
 
48.6
 
47.0
 
43.2
 
41.0
 
11.1
 
6-12
 
53.9
 
51.2
 
49.0
 
45.1
 
43.4
 
10.5
 
12-18
 
54.6
 
51.4
 
49.5
 
49.3
 
44.0
 
10.6
 
24-30
 
48.6
 
45.8
 
44.5
 
41.1
 
39.5
 
9.1

Table 8. Saturated hydraulic conductivity of selected soil depths.
Depth Site
1 2 3 4
Inches ---------------inches hr-1 
0-6
 
5.46*
 
8.10*
 
5.60*
 
5.10*
 
6-12
 
0.12 
3.26 
0.01 
0.01 
12-18
 
0.04 
0.27 
0.01 
0.02 
18-24
 
0.02 
0.34 
0.01 
0.01
*Contains dense root mat and large macrovoids.

Table 9. Iron fractionation of Sharkey pedons.
Sites
Depth 1 2 3 4
Fe0 Fed Fe0 Fed Fe0 Fed Fe0 Fed
Inches ---------------mg kg-1(ppm)--------------
0 12,088 2,713 11,189 2,967 10,228 2,644 13,442 3,848
10 9,722 3,187 8,942 4,011 9,161 3,886 11,208 3,375
20 8,002 2,644 8,387 4,439 10,430 3,861 11,208 8,406
30 10,640 4,189 3,246 3,875 9,907 7,328 10,496 9,820
40 11,525 5,905 3,567 3,317 6,530 12,540 6,705 10,554
50 8,075 5,176 1,804 2,528 2,387 10,501 5,242 8,692
60 9,713 4,656 2,656 2,589 1,500 10,302 4,781 8,729
70 10,220 6,165 3,451 2,777 2,239 12,187 3,655 8,104
Fe0 - Oxalate extractable; Fed - dithionite extractable

Table 10. Total Fe contents of Sharkey pedons
Depth Sites
1 2 3 4
Inches --------------mg kg -1---------------
0 43,200 38,000 39,600 44,600
10 43,800 39,400 43,000 44,800
20 42,800 37,400 46,000 51,000
30 44,800 26,600 46,200 50,200
40 44,800 27,400 46,800 46,600
50 40,000 19,800 37,200 43,200
60 42,800 22,800 29,600 41,400
70 44,600 26,000 31,200 37,000

Table 11. Exchangeable Fe contents of Sharkey pedons.
Depth Sites
1 2 3 4
Inches ---------------mg kg-1 (ppm)---------------
0 0.78 0.48 0.95 0.28
10 0.88 0.55 0.89 0.89
20 0.62 0.37 0.94 0.84
30 0.49 0.30 0.68 0.83
40 0.53 0.30 0.98 0.55
50 0.96 0.23 0.64 0.94
60 0.46 0.31 0.75 0.71
70 0.56 0.28 0.35 0.53

Table 12. Dithionite extractable Mn contents of Sharkey pedons.
Depth Sites
1 2 3 4
Inches ---------------mg kg-1 (ppm)---------------
0 628 291 578 746
10 117 131 348 354
20 243 219 576 503
30 282 510 650 511
40 548 243 948 1,696
50 556 266 434 249
60 492 294 476 130
70 429 239 396 252

Table 13. Temporal tests with a, a-1 dipyridyl on freshly broken soil peds at different moisture contents indicating positive (+) or negative (-) reaction for ferrous Fe.
Depth Date
1-30-92 4-28-92 7-8-92 10-18-93 1-24-94
Inches Rx % H2O Rx % H2O Rx % H2O Rx % H2O Rx % H2O
  Site 1
0-5 -- 64.1 -- 52.1 -- 36.1 -- 42.5 -- 52.2
10 -- 50.6 -- 44.8 -- 38.2 -- 47.9 -- 47.2
20 -- 40.4 -- 45.3 -- 36.0 -- 47.4 -- 41.0
30 -- 34.2 -- 37.8 -- 35.7 -- 38.4 -- 26.8
40 -- 38.2 -- 33.5 -- 31.8 -- 35.8 -- 22.3
50 -- 38.3 -- 38.3 -- 35.4 -- 29.7 -- 22.4
60 -- 38.4 -- 36.7 -- 36.2 -- 38.6 -- 23.7
  Site 2
0-5 -- 65.0 -- 50.4 -- 36.0 -- 37.5 -- 49.5
10 -- 42.1 -- 42.1 -- 36.1 -- 35.6 -- 52.1
20 -- 33.2 -- 26.9 -- 24.1 -- 43.7 -- 40.0
30 -- 27.7 -- 26.8 -- 23.3 -- 34.6 -- 29.6
40 -- 24.8 -- 28.3 -- 25.3 -- 25.9 -- 28.3
50 -- 20.8 -- 31.4 -- 21.9 -- 23.1 -- 35.2
60 -- 29.4 -- 30.9 -- 28.1 -- 19.4 -- 36.0
Site 3
0-5 -- 67.4 -- 49.4 -- 33.6 -- 37.1 -- 56.5
10 -- 55.1 -- 46.7 -- 37.0 -- 47.4 -- 56.1
20 -- 47.5 -- 44.5 -- 34.3 -- 44.3 -- 53.9
30 -- 39.0 -- 43.8 -- 33.9 -- 33.0 -- 36.9
40 -- 35.4 -- 36.8 -- 35.9 -- 32.6 -- 33.1
50 -- 34.3 -- 33.5 -- 31.7 -- 31.9 -- 33.2
60 -- 23.8 -- 20.8 -- 26.7 -- 26.5 -- 24.1
  Site 4
0-5 -- 62.9 -- 43.9 -- 40.8 -- 41.4 -- 51.2
10 -- 50.7 -- 50.8 -- 36.8 -- 42.7 -- 51.0
20 -- 50.6 -- 48.0 -- 38.6 -- 39.4 -- 48.5
30 -- 37.9 -- 42.9 -- 37.7 -- 39.0 -- 34.8
40 -- 36.2 -- 38.0 -- 37.7 -- 38.1 -- 34.1
50 -- 36.9 -- 39.3 -- 36.3 -- 39.9 -- 34.7
60 -- 34.9 -- 35.5 -- 37.0 -- 40.4 -- 35.6