Development of reference bulk density routine (Files referenced are appended at end for reference)

Proctor density data is not available for high organic matter soils. High OM soils data is published (Thomas Keller, Inge Håkansson. 2010. Estimation of reference bulk density from soil particle size distribution and soil organic matter content. Geoderma 154:398–406.) but is for a reference bulk density (pressed for 7 days at high water content under 200 kPa pressure)

Standard soil analysis practice is to not measure sand, silt and clay for OM content above 35% due to the questionable accuracy of the values depending on the measurement technique. Therefore the fitted equation (reported by Keller and Håkansson) does not work for >35% OM where no mineral portion was reported. As a first attempt, the points with OM >30% were placed in the file 'omdata.txt', a point for 100% OM added (average BD from the 4 highest OM data points) and fit to the equation using gnuplot:

Note: Data points are in %. Values in WEPS are in fraction. Values converted to fraction in equations and fitted and tested accordingly.

---BEGIN fit-om.plt---
# first guess values
a=0.36
b=100.0
c=0.25
# equation for BD as a function of high OM content
f(x) = a+1/(b*(x-c)*(x-c)+1)
fit f(x) 'omdata.txt' using ($2/100):1 via a,b,c
# result of the fit
a = 0.35262
b = 211.036
c = 0.236408
plot f(x), 'omdata.txt' using ($2/100):1 with points
pause -1
q1=1.308
q2=1.19
q3=1.03
q4=1.8
q5=0.8
q6=6.2
q7=5.9
# comparison of equations with data, plotted against OM content fraction
plot 'refdata.txt' using ($5/100):(q1+q2*$2/100+q3*$4/100-q4*$2/100*$2/100-q5*$4/100*$4/100-q6*$3/100*$5/100-q7*$4/100*$5/100) \
   , 'refdata.txt' using ($5/100):1 \
   , f(x) with lines \
   , 'omdata.txt' using ($2/100):1 with points
pause -1
# composite equation values compared against data values, one to one line plotted
plot x \
   , 'refdata.txt' using 1:($5<30 ? (q1+q2*$2/100+q3*$4/100-q4*$2/100*$2/100-q5*$4/100*$4/100-q6*$3/100*$5/100-q7*$4/100*$5/100) : a+1/(b*($5/100-c)*($5/100-c)+1)) \
   , 'omdata.txt' using 1:(a+1/(b*($2/100-c)*($2/100-c)+1))
pause -1
---END fit-om.plt---

Based on the above fit, the composite equation was implemented in util/lib_misc/soilden_mod.f95 function setbdref, and the 'testdata.txt' file was generated for the 12 soil texture classes. Using this composite function breaks down for intermediate organic matter content values. The function fit my the authors does poorly for OM values between 15% and 30% as illustrated with this data set with varied texture and OM content. The file testdata.txt was created by programmingthe composite function above in fortran, and creating a range of OM content for each of the 12 standard texture classes. The plot illustrates the difficulty created by this method, esp. for the Sand texture.

---BEGIN test-om.plt---
pflg = 2
set xlabel 'OM'
set ylabel 'Reference Bulk Density (Mg/m^3)'
set title 'Sand'
plot 'testdata.txt' index 0 using 5:4:1 with labels
pause pflg
set title 'Loamy Sand'
plot 'testdata.txt' index 1 using 5:4:1 with labels
pause pflg
set title 'Sandy Loam'
plot 'testdata.txt' index 2 using 5:4:1 with labels
pause pflg
set title 'Loam'
plot 'testdata.txt' index 3 using 5:4:1 with labels
pause pflg
set title 'Silt Loam'
plot 'testdata.txt' index 4 using 5:4:1 with labels
pause pflg
set title 'Sandy Clay Loam'
plot 'testdata.txt' index 5 using 5:4:1 with labels
pause pflg
set title 'Clay Loam'
plot 'testdata.txt' index 6 using 5:4:1 with labels
pause pflg
set title 'Silty Clay Loam'
plot 'testdata.txt' index 7 using 5:4:1 with labels
pause pflg
set title 'Sandy Clay'
plot 'testdata.txt' index 8 using 5:4:1 with labels
pause pflg
set title 'Silty Clay'
plot 'testdata.txt' index 9 using 5:4:1 with labels
pause pflg
set title 'Clay'
plot 'testdata.txt' index 10 using 5:4:1 with labels
pause pflg
---END test-om.plt---

Based on the plots above, it was decided to use the settled bulk density of Rawls (as implemented in WEPS) as a normalizing value. The reference bulk density can be modeled based on the difference (diff), the ratio (ratio) or the ratio of the difference (drat). test_soil_density is programmed with each of these functions and 'refdata.txt' processed resulting in odat_diff.txt, odat_ratio.txt and odat_drat.txt, including the settled bulk density for each high organic matter point using representative Sand, Silt, Clay values for all twelve soil texture classes.

For all three models, the normalized values show a strong trend in relation to sand content. The normalized values of low organic matter data points are fit to a second order fourier function with respect to sand content. The high organic content points are averaged in order to get a value for 100% organic matter content.

---BEGIN Averaging Script---
 test_soil_density odat diff
 cat odat_diff.txt | dm "if INLINE > 1 then INPUT else SKIP" | dm "if x8 > 0.35 then INPUT else SKIP" | colex 4 | stats mean
 test_soil_density odat ratio
 cat odat_ratio.txt | dm "if INLINE > 1 then INPUT else SKIP" | dm "if x8 > 0.35 then INPUT else SKIP" | colex 4 | stats mean
 test_soil_density odat drat
 cat odat_drat.txt | dm "if INLINE > 1 then INPUT else SKIP" | dm "if x8 > 0.35 then INPUT else SKIP" | colex 4 | stats mean
---END Averaging Script---

diff_mean = 0.0666647
ratio_mean = 1.19378
rdat_mean = 0.193782

---BEGIN odat_diff.plt---
set yrange [0:]
set xrange [0:1]
pflg = -1
set ylabel 'Reference-Settled BD (Mg/m^3)'
set xlabel 'OM'
plot 'odat_diff.txt' using 8:4 with points title 'All OM'
pause pflg
set xlabel 'Sand'
plot 'odat_diff.txt' using 7:4 with points title 'All OM'
pause pflg
set xlabel 'Sand'
plot 'odat_diff.txt' using ($8<0.35?($7):NaN):4 with points title 'OM<35%'
pause pflg
set xlabel 'Silt'
plot 'odat_diff.txt' using 6:4 with points title 'All OM'
pause pflg
set xlabel 'Silt'
plot 'odat_diff.txt' using ($8<0.35?($6):NaN):4 with points title 'OM<35%'
pause pflg
set xlabel 'Clay'
plot 'odat_diff.txt' using 5:4 with points title 'All OM'
pause pflg
set xlabel 'Clay'
plot 'odat_diff.txt' using ($8<0.35?($5):NaN):4 with points title 'OM<35%'
pause pflg
exit
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*exp(f*x)
#fit f(x) 'odat_diff.txt' using 7:4 via a,b,c,d,e,f
# final sum of squares of residuals : 0.77258
a = 0.254494       #  +/- 0.8115       (318.9%)
b = 0.910623       #  +/- 1.433e+10    (1.574e+12%)
c = 0.41558        #  +/- 2.562e+10    (6.164e+12%)
d = -4.0794        #  +/- 2.816e+10    (6.904e+11%)
e = -0.937184      #  +/- 0.6643       (70.88%)
f = -4.70351       #  +/- 2.426        (51.58%)
plot f(x), 'odat_diff.txt' using 7:4 with points
pause pflg
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*sin(f*x)
#fit f(x) 'odat_diff.txt' using 7:4 via a,b,c,d,e,f
# final sum of squares of residuals : 0.758665
a = -6.82882       #  +/- 1.207        (17.67%)
b = -4.96788       #  +/- 6.764e+10    (1.362e+12%)
c = 2.32028        #  +/- 2.457e+10    (1.059e+12%)
d = -1.04948       #  +/- 4.953e+09    (4.719e+11%)
e = -3.02462       #  +/- 0.8598       (28.43%)
f = 2.15669        #  +/- 0.3891       (18.04%)
plot f(x), 'odat_diff.txt' using 7:4 with points
pause pflg
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
g = 1
h = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*sin(f*x) + g*cos(h*x)
#fit f(x) 'odat_diff.txt' using 7:4 via a,b,c,d,e,f,g,h
#final sum of squares of residuals : 0.747182
a = 0.100419       #  +/- 11.4         (1.135e+04%)
b = 0.499643       #  +/- 6.176e+09    (1.236e+12%)
c = -0.201248      #  +/- 1.535e+10    (7.628e+12%)
d = -4.77603       #  +/- 3.075e+10    (6.439e+11%)
e = 1.11687        #  +/- 11.76        (1053%)
f = 2.61841        #  +/- 13.24        (505.5%)
g = 0.323616       #  +/- 1.315        (406.4%)
h = 4.99596        #  +/- 7.6          (152.1%)
plot f(x), 'odat_diff.txt' using 7:4 with points
pause pflg
a = 1
b = 1
c = 1
d = 1
f(x) = a*cos(x) + b*sin(x) + c*cos(2*x) + d*sin(2*x)
#fit f(x) 'odat_diff.txt' using 7:4 via a,b,c,d
# final sum of squares of residuals : 0.773553
a = -2.57058       #  +/- 0.2528       (9.835%)
b = 4.09442        #  +/- 0.5145       (12.56%)
c = 2.61977        #  +/- 0.2402       (9.168%)
d = -0.940779      #  +/- 0.1928       (20.5%)
plot f(x), 'odat_diff.txt' using 7:4 with points
pause pflg
exit
---END odat_diff.plt---

---BEGIN odat_ratio.plt---
set yrange [1:]
set xrange [0:1]
pflg = -1
set ylabel 'Reference/Settled BD (Mg/m^3)'
set xlabel 'OM'
plot 'odat_ratio.txt' using 8:4 with points title 'All OM'
pause pflg
set xlabel 'Sand'
plot 'odat_ratio.txt' using 7:4 with points title 'All OM'
pause pflg
set xlabel 'Sand'
plot 'odat_ratio.txt' using ($8<0.35?($7):NaN):4 with points title 'OM<35%'
pause pflg
set xlabel 'Silt'
plot 'odat_ratio.txt' using 6:4 with points title 'All OM'
pause pflg
set xlabel 'Silt'
plot 'odat_ratio.txt' using ($8<0.35?($6):NaN):4 with points title 'OM<35%'
pause pflg
set xlabel 'Clay'
plot 'odat_ratio.txt' using 5:4 with points title 'All OM'
pause pflg
set xlabel 'Clay'
plot 'odat_ratio.txt' using ($8<0.35?($5):NaN):4 with points title 'OM<35%'
pause pflg
exit
pflg = 5
set xlabel 'Sand'
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*exp(f*x)
#fit f(x) 'odat_ratio.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d,e,f
#final sum of squares of residuals : 1.05669
a               = -0.592157      #  +/- 57.22        (9663%)
b               = -2.93319       #  +/- 1.684e+10    (5.74e+11%)
c               = 0.853777       #  +/- 4.167e+10    (4.88e+12%)
d               = -4.2057        #  +/- 1.422e+10    (3.381e+11%)
e               = -1.53158       #  +/- 426.4        (2.784e+04%)
f               = 0.800238       #  +/- 66.57        (8318%)
plot f(x), 'odat_ratio.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*sin(f*x)
#fit f(x) 'odat_ratio.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d,e,f
#final sum of squares of residuals : 1.00515
a               = -3.64523       #  +/- 2.171        (59.55%)
b               = -4.69548       #  +/- 5.472e+10    (1.165e+12%)
c               = 1.42433        #  +/- 3.52e+10     (2.472e+12%)
d               = -1.34869       #  +/- 7.505e+09    (5.565e+11%)
e               = -1.80162       #  +/- 5.343        (296.6%)
f               = 1.96521        #  +/- 2.72         (138.4%)
plot f(x), 'odat_ratio.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
g = 1
h = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*sin(f*x) + g*cos(h*x)
#fit f(x) 'odat_ratio.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d,e,f,g,h
#final sum of squares of residuals : 1.00686
a               = -0.199255      #  +/- 2585         (1.298e+06%)
b               = -0.894163      #  +/- 9.435e+09    (1.055e+12%)
c               = 0.954062       #  +/- 2.115e+10    (2.216e+12%)
d               = -4.99055       #  +/- 2.368e+10    (4.744e+11%)
e               = 0.631356       #  +/- 9.669e+05    (1.532e+08%)
f               = 0.588887       #  +/- 2.999e+05    (5.092e+07%)
g               = 0.676088       #  +/- 1317         (1.947e+05%)
h               = 2.70479        #  +/- 1222         (4.518e+04%)
plot f(x), 'odat_ratio.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
a = 1
b = 1
c = 1
d = 1
f(x) = a*cos(x) + b*sin(x) + c*cos(2*x) + d*sin(2*x)
#fit f(x) 'odat_ratio.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d
#final sum of squares of residuals : 1.00632
a               = -0.516472      #  +/- 0.5369       (104%)
b               = 3.46117        #  +/- 1.25         (36.11%)
c               = 1.64331        #  +/- 0.5152       (31.35%)
d               = -0.965802      #  +/- 0.5011       (51.89%)
plot f(x), 'odat_ratio.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
exit
---END odat_ratio.plt---

---BEGIN odat_drat.plt---
set yrange [0:]
set xrange [0:1]
pflg = -1
set ylabel 'Reference/Settled BD (Mg/m^3)'
set xlabel 'OM'
plot 'odat_drat.txt' using 8:4 with points title 'All OM'
pause pflg
set xlabel 'Sand'
plot 'odat_drat.txt' using 7:4 with points title 'All OM'
pause pflg
set xlabel 'Sand'
plot 'odat_drat.txt' using ($8<0.35?($7):NaN):4 with points title 'OM<35%'
pause pflg
set xlabel 'Silt'
plot 'odat_drat.txt' using 6:4 with points title 'All OM'
pause pflg
set xlabel 'Silt'
plot 'odat_drat.txt' using ($8<0.35?($6):NaN):4 with points title 'OM<35%'
pause pflg
set xlabel 'Clay'
plot 'odat_drat.txt' using 5:4 with points title 'All OM'
pause pflg
set xlabel 'Clay'
plot 'odat_drat.txt' using ($8<0.35?($5):NaN):4 with points title 'OM<35%'
pause pflg
exit
pflg = 5
set xlabel 'Sand'
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*exp(f*x)
#fit f(x) 'odat_drat.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d,e,f
#final sum of squares of residuals : 1.05783
a               = -0.523935      #  +/- 53.14        (1.014e+04%)
b               = -2.54544       #  +/- 1.231e+10    (4.835e+11%)
c               = 0.846633       #  +/- 2.987e+10    (3.528e+12%)
d               = -4.45513       #  +/- 1.175e+10    (2.636e+11%)
e               = -1.60272       #  +/- 377.2        (2.354e+04%)
f               = 0.817038       #  +/- 57.28        (7011%)
plot f(x), 'odat_drat.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*sin(f*x)
#fit f(x) 'odat_drat.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d,e,f
#final sum of squares of residuals : 1.00529
a               = -3.58578       #  +/- 2.148        (59.9%)
b               = -4.29519       #  +/- 6.029e+10    (1.404e+12%)
c               = 0.969094       #  +/- 3.606e+10    (3.722e+12%)
d               = -1.36937       #  +/- 8.406e+09    (6.139e+11%)
e               = -2.1641        #  +/- 8.512        (393.3%)
f               = 1.81974        #  +/- 3.139        (172.5%)
plot f(x), 'odat_drat.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
a = -1
b = -1
c = 1
d = -5
e = 1
f = 1
g = 1
h = 1
f(x) = a*(x+d)*(x+d) + b*(x+d) + c + e*sin(f*x) + g*cos(h*x)
#fit f(x) 'odat_drat.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d,e,f,g,h
#final sum of squares of residuals : 1.00684
a               = -0.238457      #  +/- 2168         (9.091e+05%)
b               = -0.911753      #  +/- 1.394e+10    (1.529e+12%)
c               = 0.715569       #  +/- 2.661e+10    (3.719e+12%)
d               = -4.89641       #  +/- 2.922e+10    (5.968e+11%)
e               = 0.136044       #  +/- 1.329e+07    (9.766e+09%)
f               = 0.335704       #  +/- 1.091e+07    (3.251e+09%)
g               = 0.666854       #  +/- 1108         (1.661e+05%)
h               = 2.70843        #  +/- 1050         (3.877e+04%)
plot f(x), 'odat_drat.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
a = 1
b = 1
c = 1
d = 1
f(x) = a*cos(x) + b*sin(x) + c*cos(2*x) + d*sin(2*x)
#fit f(x) 'odat_drat.txt' using ($8<0.35?($7):(1/0)):4 via a,b,c,d
#final sum of squares of residuals : 1.00689
a               = -1.75229       #  +/- 0.5371       (30.65%)
b               = 2.92099        #  +/- 1.25         (42.8%)
c               = 1.88065        #  +/- 0.5153       (27.4%)
d               = -0.709907      #  +/- 0.5013       (70.61%)
plot f(x), 'odat_drat.txt' using ($8<0.35?($7):NaN):4 with points
pause pflg
exit
---END odat_drat.plt---

The values produced by each of the models for the data set are placed in the files value_diff.txt, value_ratio.txt and value_rdat.txt and the goodness of each model is evaluated using paired points analysis. 

---BEGIN Paired Analysis Script---
test_soil_density value diff
cat value_diff.txt | dm "if INLINE > 1 then INPUT else SKIP" | colex 3 4 | pair -s
test_soil_density value ratio
cat value_ratio.txt | dm "if INLINE > 1 then INPUT else SKIP" | colex 3 4 | pair -s
test_soil_density value drat
cat value_drat.txt | dm "if INLINE > 1 then INPUT else SKIP" | colex 3 4 | pair -s
---END Paired Analysis Script---

Comparing the means and standard deviation of the difference of the two columns, the difference ratio method has the smallest mean and standard deviation, best t value and highest p for the difference between the modeled columns and the data column.

value_diff.txt Analysis for 231 points:
                         Column 1         Column 2       Difference
Minimums                   0.3670           0.3577          -0.1624
Maximums                   1.8170           1.8623           0.2483
Sums                     281.1990         275.3430           5.8560
SumSquares               398.1717         377.3710           1.4992
Means                      1.2173           1.1920           0.0254
SDs                        0.4928           0.4624           0.0766
t(230)                    37.5407          39.1804           5.0278
p                          0.0000           0.0000           0.0000

     Correlation        r-squared           t(229)                p
          0.9892           0.9784         101.8900           0.0000
       Intercept            Slope
          0.0623           0.9280

value_ratio.txt Analysis for 231 points:
                         Column 1         Column 2       Difference
Minimums                   0.3670           0.3321          -0.2314
Maximums                   1.8170           1.9538           0.2180
Sums                     281.1990         281.7599          -0.5609
SumSquares               398.1717         399.8484           1.2621
Means                      1.2173           1.2197          -0.0024
SDs                        0.4928           0.4942           0.0740
t(230)                    37.5407          37.5117          -0.4985
p                          0.0000           0.0000           0.6186

     Correlation        r-squared           t(229)                p
          0.9888           0.9776         100.0366           0.0000
       Intercept            Slope
          0.0128           0.9915

value_drat.txt Analysis for 231 points:
                         Column 1         Column 2       Difference
Minimums                   0.3670           0.3263          -0.2312
Maximums                   1.8170           1.9542           0.2223
Sums                     281.1990         281.2526          -0.0536
SumSquares               398.1717         398.6575           1.2752
Means                      1.2173           1.2175          -0.0002
SDs                        0.4928           0.4944           0.0745
t(230)                    37.5407          37.4290          -0.0474
p                          0.0000           0.0000           0.9623

     Correlation        r-squared           t(229)                p
          0.9886           0.9774          99.4863           0.0000
       Intercept            Slope
          0.0103           0.9918

This reference bulk density relationship with Proctor density data from the WEPP and SERDP data sets may be adequate. For comparison, the Proctor density model from Wagner et al. 1994 was programmed and fit to the reference data set, the data set from the paper (WEPP data set) and the data set from the SERDP project (SERDP data set).

Wagner, L.E., Ambe, N.M., Ding, D. Estimating a Proctor Density Curve from Intrinsic Soil Properties. Trans of the ASAE; 1994; 37((4)): 1121-1125.

The Optimal Water Content function developed in the paper (Om content < 3.13%) shows instability for OM contents above 5%.
This functional relationship was developed using the WEPP data set. Since the SERDP data set is independent, the goodness of fit with the regression is compared against the goodness of fit original data set.

---BEGIN show-owc-procden.plt---
# NOTE: data file values are percent, not fraction
set term wxt size 900,500
set key bottom
owc_a0 = 21.09
owc_a1 = -0.2892
owc_a2 = 0.007075
owc_a3 = -0.001375
owc_a4 = 0.4234
owc(clay, sand, om) = owc_a0 + owc_a1*clay + owc_a2*clay*clay + owc_a3*sand*sand + owc_a4*om*om
den_organic = 1.23
den_quartz = 2.65
pden(om) = 1.0 / ((om/100.0)/den_organic + (1.0-(om/100.0))/den_quartz)
procden(clay,sand,om) = pden(om) / (1.0 + pden(om)*owc(clay,sand,om)/80.0)
set term wxt 1
set xlabel 'fit OWC (%)'
set ylabel 'data OWC (%)'
plot x, 'proctor-wepp.txt' using (owc($3,$4,$5)):6 with points, 'proctor-serdp.txt' using (owc($2,$4,$5)):6 with points
set term wxt 2
set xlabel 'Fit Proctor BD (Mg/m^3)'
set ylabel 'Data BD (Mg/m^3)'
plot x, 'proctor-wepp.txt' using (procden($3,$4,$5)):7 with points, 'proctor-serdp.txt' using (procden($2,$4,$5)):7 with points

set table "temp.out"
plot 'proctor-wepp.txt' using (owc($3,$4,$5)):6 with points
unset table
!cat temp.out | dm "if INLINE > 4 then INPUT else SKIP" | colex 1 2 | pair -s
set table "temp.out"
plot 'proctor-serdp.txt' using (owc($2,$4,$5)):6 with points
unset table
!cat temp.out | dm "if INLINE > 4 then INPUT else SKIP" | colex 1 2 | pair -s
set table "temp.out"
plot 'proctor-wepp.txt' using (procden($3,$4,$5)):7 with points
unset table
!cat temp.out | dm "if INLINE > 4 then INPUT else SKIP" | colex 1 2 | pair -s
set table "temp.out"
plot 'proctor-serdp.txt' using (procden($2,$4,$5)):7 with points
unset table
!cat temp.out | dm "if INLINE > 4 then INPUT else SKIP" | colex 1 2 | pair -s
!rm temp.out
---END show-owc-procden.plt---

Fit comparison for OWC for WEPP data
Analysis for 39 points:
                         Column 1         Column 2       Difference
Minimums                   8.5306           8.0000          -3.5307
Maximums                  27.2244          26.0000           3.1422
Sums                     662.0644         662.0000           0.0644
SumSquares             11948.0020       12050.0000         104.2232
Means                     16.9760          16.9744           0.0017
SDs                        4.3188           4.6254           1.6561
t(38)                     24.5471          22.9181           0.0062
p                          0.0000           0.0000           0.9951

     Correlation        r-squared            t(37)                p
          0.9337           0.8718          15.8623           0.0000
       Intercept            Slope
         -0.0012           1.0000

Fit comparison for OWC for SERDP data
Analysis for 36 points:
                         Column 1         Column 2       Difference
Minimums                   9.1566           7.7693          -4.5782
Maximums                  28.7757          26.0364           8.3252
Sums                     653.7300         581.4578          72.2722
SumSquares             13173.1731       10553.5720         333.1002
Means                     18.1592          16.1516           2.0076
SDs                        6.0991           5.7622           2.3177
t(35)                     17.8640          16.8182           5.1971
p                          0.0000           0.0000           0.0000

     Correlation        r-squared            t(34)                p
          0.9252           0.8560          14.2154           0.0000
       Intercept            Slope
          0.2791           0.8741

Fit comparison for PROCDEN for WEPP data
Analysis for 39 points:
                         Column 1         Column 2       Difference
Minimums                   1.3674           1.4600          -0.1190
Maximums                   2.0615           1.9900           0.2915
Sums                      66.1775          65.6900           0.4875
SumSquares               113.3163         111.3523           0.2988
Means                      1.6969           1.6844           0.0125
SDs                        0.1640           0.1364           0.0878
t(38)                     64.6067          77.1300           0.8895
p                          0.0000           0.0000           0.3793

     Correlation        r-squared            t(37)                p
          0.8449           0.7139           9.6077           0.0000
       Intercept            Slope
          0.4923           0.7025

Fit comparison for PROCDEN for SERDP data
Analysis for 36 points:
                         Column 1         Column 2       Difference
Minimums                   1.3179           1.4364          -0.2648
Maximums                   2.0276           1.9559           0.2663
Sums                      59.6409          61.1836          -1.5427
SumSquares               100.5201         104.7928           0.5864
Means                      1.6567           1.6995          -0.0429
SDs                        0.2213           0.1520           0.1219
t(35)                     44.9256          67.0930          -2.1088
p                          0.0000           0.0000           0.0422

     Correlation        r-squared            t(34)                p
          0.8503           0.7231           9.4216           0.0000
       Intercept            Slope
          0.7319           0.5841

The fit of optimum water content to the WEPP data set is better than the ability of the fit to model the SERDP data set. The mean of the residuals changes from 0.0017 for WEPP to 2.0076 for SERDP and the standard deviation increases from 1.6561 for WEPP to 2.3177 for SERDP. Similarly, using the WEPP fit OWC relationship to model the proctor density, the mean of the residual changes from 0.0125 for WEPP to -0.0429 for SERDP and the standard deviation increases from 0.0878 for WEPP to 0.1219 for SERDP. Plotting the two data sets together for the independent variables show that

---BEGIN show-wepp-serdp.plt---
set xrange [0:]
set term wxt size 900,500
set key bottom
set term wxt 1
set xlabel 'clay (%)'
set ylabel 'data OWC (%)'
plot 'proctor-wepp.txt' using 3:6 with points, 'proctor-serdp.txt' using 2:6 with points
set term wxt 2
set xlabel 'sand (%)'
plot 'proctor-wepp.txt' using 4:6 with points, 'proctor-serdp.txt' using 4:6 with points
set term wxt 3
set xlabel 'OM (%)'
plot 'proctor-wepp.txt' using 5:6 with points, 'proctor-serdp.txt' using 5:6 with points
---END show-wepp-serdp.plt---

Optimum water content increases with increasing OM and clay, and decreases with increasing sand. Fitting to a simple linear model:

---BEGIN fit-wepp-serdp-owc.plt---
# create composite data set
!cat proctor-wepp.txt | colex 1 3 4 5 6 7 > proctor-wepp-serdp.txt
!cat proctor-serdp.txt | colex 1 2 4 5 6 7 >> proctor-wepp-serdp.txt
owc_a = 16
owc_b = 1
owc_c = -1
owc_d = 1
owc(clay,sand,om) = owc_a + owc_b*clay + owc_c*sand + owc_d*om
fit [clay=0:100] [sand=0:100] [om=0:100] owc(clay,sand,om) 'proctor-wepp-serdp.txt' using 2:3:4:5:(1) via owc_a,owc_b,owc_c,owc_d
# result of fit
owc_a           = 16.0932        #  +/- 1.32         (8.201%)
owc_b           = 0.129032       #  +/- 0.02986      (23.14%)
owc_c           = -0.0883454     #  +/- 0.0147       (16.64%)
owc_d           = 1.06305        #  +/- 0.2585       (24.32%)
# plot the residuals
set xrange [0:]
set term wxt size 900,500
set key bottom
set term wxt 1
set xlabel 'clay (%)'
set ylabel 'residual OWC (%)'
plot 'proctor-wepp-serdp.txt' using 2:($5-owc($2,$3,$4)) with points
set term wxt 2
set xlabel 'sand (%)'
plot 'proctor-wepp-serdp.txt' using 3:($5-owc($2,$3,$4)) with points
set term wxt 3
set xlabel 'OM (%)'
plot 'proctor-wepp-serdp.txt' using 4:($5-owc($2,$3,$4)) with points
# find goodness of fit
set table "temp.out"
plot 'proctor-wepp-serdp.txt' using (owc($2,$3,$4)):5 with points
unset table
!cat temp.out | dm "if INLINE > 4 then INPUT else SKIP" | colex 1 2 | pair -s
!rm temp.out
---END fit-wepp-serdp-owc.plt---

Analysis for 75 points:
                         Column 1         Column 2       Difference
Minimums                   8.6060           7.7693          -5.5421
Maximums                  24.4677          26.0364           3.3199
Sums                    1243.4614        1243.4578           0.0036
SumSquares             22289.4528       22603.5720         314.2432
Means                     16.5795          16.5794           0.0000
SDs                        4.7555           5.1828           2.0607
t(74)                     30.1929          27.7036           0.0002
p                          0.0000           0.0000           1.0000

     Correlation        r-squared            t(73)                p
          0.9176           0.8419          19.7170           0.0000
       Intercept            Slope
         -0.0000           1.0000

The standard deviation for this composite set is greater than the original WEPP data set fit, but less than using that fit for the SERDP data set. Using this OWC relationship to predict the Proctor Density results in:

---BEGIN new-owc-procden.plt---
# NOTE: data file values are percent, not fraction
set term wxt size 900,500
set key bottom
owc_a           = 16.0932        #  +/- 1.32         (8.201%)
owc_b           = 0.129032       #  +/- 0.02986      (23.14%)
owc_c           = -0.0883454     #  +/- 0.0147       (16.64%)
owc_d           = 1.06305        #  +/- 0.2585       (24.32%)
owc(clay,sand,om) = owc_a + owc_b*clay + owc_c*sand + owc_d*om
den_organic = 1.23
den_quartz = 2.65
pden(om) = 1.0 / ((om/100.0)/den_organic + (1.0-(om/100.0))/den_quartz)
procden(clay,sand,om) = pden(om) / (1.0 + pden(om)*owc(clay,sand,om)/80.0)
set xlabel 'Fit Proctor BD (Mg/m^3)'
set ylabel 'Data BD (Mg/m^3)'
plot x, 'proctor-wepp-serdp.txt' using (procden($2,$3,$4)):6 with points

set table "temp.out"
plot 'proctor-wepp-serdp.txt' using (procden($2,$3,$4)):6 with points
unset table
!cat temp.out | dm "if INLINE > 4 then INPUT else SKIP" | colex 1 2 | pair -s
!rm temp.out
---END new-owc-procden.plt---

Analysis for 75 points:
                         Column 1         Column 2       Difference
Minimums                   1.4273           1.4364          -0.2137
Maximums                   2.0563           1.9900           0.3303
Sums                     128.1673         126.8736           1.2937
SumSquares               221.5860         216.1451           0.9044
Means                      1.7089           1.6916           0.0172
SDs                        0.1860           0.1433           0.1092
t(74)                     79.5483         102.2339           1.3682
p                          0.0000           0.0000           0.1754

     Correlation        r-squared            t(73)                p
          0.8107           0.6572          11.8313           0.0000
       Intercept            Slope
          0.6245           0.6244

The result is a standard deviation that is also greater than the original WEPP data set fit, but less than using that fit for the SERDP data set. Using this relationship with high organic matter soils

running 'test_soil_density wepp' creates 'proc-wepp-ref.txt'
running 'test_soil_density serdp' creates 'proc-serdp-ref.txt'
running 'test_soil_density pref' creates 'proc-pref-ref.txt'

---BEGIN ref-new-owc-procden.plt---
# NOTE: data file values are fraction, not percent
set term wxt size 1800,1000
set key bottom
owc_a           = 16.0932
owc_b           = 0.129032*100
owc_c           = -0.0883454*100
owc_d           = 1.06305*100
owc(clay,sand,om) = owc_a + owc_b*clay + owc_c*sand + owc_d*om
den_organic = 1.23
den_quartz = 2.65
pden(om) = 1.0 / ((om)/den_organic + (1.0-(om))/den_quartz)
procden(clay,sand,om) = pden(om) / (1.0 + pden(om)*owc(clay,sand,om)/80.0)
set term wxt 1
set xlabel 'Fit Proctor BD (Mg/m^3)'
set ylabel 'Data BD (Mg/m^3)'
plot x, 'proc-wepp-ref.txt' using (procden($8,$10,$11)):3 with points, 'proc-serdp-ref.txt' using (procden($8,$10,$11)):3 with points, 'proc-pref-ref.txt' using (procden($8,$10,$11)):3 with points
set term wxt 2
set xlabel 'OM'
set ylabel 'OWC (%)'
plot 'proc-wepp-ref.txt' using 11:(owc($8,$10,$11)) with points, 'proc-serdp-ref.txt' using 11:(owc($8,$10,$11)) with points, 'proc-pref-ref.txt' using 11:(owc($8,$10,$11)) with points 
---END ref-new-owc-procden.plt---

The proctor density relationship does not fit well for the uniaxial compression data at high organic matter content. Lacking real proctor density data values in that range, it will be adjusted later as needed.

---BEGIN proc_all.plt---
set key bottom
set xrange [0:]
pflg = -1
set term wxt size 1800,1000
set ylabel 'Data BD (Mg/m^3)'
set term wxt 1
set xlabel 'OM'
plot 'proc-wepp-ref.txt' using 11:3 with points, 'proc-serdp-ref.txt' using 11:3 with points, 'proc-pref-ref.txt' using 11:3 with points
set term wxt 2
set xlabel 'Sand'
plot 'proc-wepp-ref.txt' using 10:3 with points, 'proc-serdp-ref.txt' using 10:3 with points, 'proc-pref-ref.txt' using 10:3 with points
set term wxt 3
set xlabel 'Silt'
plot 'proc-wepp-ref.txt' using 9:3 with points, 'proc-serdp-ref.txt' using 9:3 with points, 'proc-pref-ref.txt' using 9:3 with points
set term wxt 4
set xlabel 'Clay'
plot 'proc-wepp-ref.txt' using 8:3 with points, 'proc-serdp-ref.txt' using 8:3 with points, 'proc-pref-ref.txt' using 8:3 with points
set term wxt 5
set xlabel 'PartDen (Mg/m^3)'
plot 'proc-wepp-ref.txt' using 7:3 with points, 'proc-serdp-ref.txt' using 7:3 with points, 'proc-pref-ref.txt' using 7:3 with points
set ylabel 'Data BD (Mg/m^3)'
set term wxt 6
set xlabel 'Settled BD (Mg/m^3)'
plot 'proc-wepp-ref.txt' using 4:3 with points, 'proc-serdp-ref.txt' using 4:3 with points, 'proc-pref-ref.txt' using 4:3 with points, x
set term wxt 7
set xlabel 'Reference BD (Mg/m^3)'
plot 'proc-wepp-ref.txt' using 5:3 with points, 'proc-serdp-ref.txt' using 5:3 with points, 'proc-pref-ref.txt' using 5:3 with points, x
set term wxt 8
set xlabel 'Proctor BD (Mg/m^3)'
plot 'proc-wepp-ref.txt' using 6:3 with points, 'proc-serdp-ref.txt' using 6:3 with points, 'proc-pref-ref.txt' using 6:3 with points, x
set term wxt 9
set ylabel 'Reference BD (Mg/m^3)'
set xlabel 'Proctor BD (Mg/m^3)'
plot 'proc-wepp-ref.txt' using 6:5 with points, 'proc-serdp-ref.txt' using 6:3 with points, 'proc-pref-ref.txt' using 6:3 with points, x
pause pflg
---END proc_all.plt---

The script below contains some interesting methods for gnuplot, but the results were ultimately not used.
---BEGIN fit-procden.plt---
# NOTE: data file values are fraction, not percent
set key bottom
min(x,y) = (x<y) ? x : y
owc_a0 = 21.09
owc_a1 = -0.2892*100
owc_a2 = 0.007075*10000
owc_a3 = -0.001375*10000
owc_a4 = 0.4234*10000
g(clay, sand, om) = owc_a0 + owc_a1*clay + owc_a2*clay*clay + owc_a3*sand*sand + owc_a4*om*om
a = 50
b = 1
c = 1
d = 1
f(om) = a + b / (1.0 + exp(-(om-c)/d))
owc(clay, sand, om) = min( f(om), g(clay, sand, om) )
den_organic = 1.23
den_quartz = 2.65
pden(organf) = 1.0 / (organf/den_organic + (1.0-organf)/den_quartz)
procden(clay,sand,om) = pden(om) / (1.0 + pden(om)*owc(clay,sand,om)/80.0)
fit [clay=0:1] [sand=0:1] [om=0.081:1] procden(clay,sand,om) 'proc-pref-ref.txt' using 8:10:11:3:(1) via a,b,c,d
# result of fit
a               = 169.377         # +/- 6.361        (3.755%)
b               = -151.011        # +/- 10.93        (7.237%)
c               = 0.36509         # +/- 0.009527     (2.61%)
d               = -0.101741       # +/- 0.01926      (18.93%)
set term wxt 1
set xlabel 'Fit Proctor BD (Mg/m^3)'
set ylabel 'Data BD (Mg/m^3)'
plot x, 'proc-wepp-ref.txt' using (procden($8,$10,$11)):3 with points, 'proc-serdp-ref.txt' using (procden($8,$10,$11)):3 with points, 'proc-pref-ref.txt' using (procden($8,$10,$11)):3 with points
set term wxt 2
set xlabel 'OM'
set ylabel 'OWC (%)'
plot 'proc-wepp-ref.txt' using 11:(owc($8,$10,$11)) with points, 'proc-serdp-ref.txt' using 11:(owc($8,$10,$11)) with points, 'proc-pref-ref.txt' using 11:(owc($8,$10,$11)) with points 
---END fit-procden.plt---

refdata.txt  - data from Keller and Håkansson
---BEGIN refdata.txt---
dat_nam ref_den	clay	Silt	Sand	OM	
Wa	1.485	14.5	69.1	16.3	3.4	
Wa	1.362	10.3	72.1	17.6	2.9	
Wa	1.404	10.1	70.4	19.4	2.6	
Wa	1.427	10.1	71.5	18.5	2.6	
Wa	1.427	9.4	70.1	20.5	2.6	
Wa	1.398	8.9	74.0	17.1	2.4	
Wa	1.423	8.9	69.8	21.3	2.4	
Wa	1.389	7.9	63.4	28.7	3.3	
I	1.518	48.6	29.1	22.3	4.5	
I	1.550	47.3	29.6	23.1	4.0	
I	1.569	41.0	32.5	26.5	4.2	
I	1.591	38.8	40.9	20.3	3.2	
I	1.579	38.0	29.0	33.1	4.0	
I	1.563	36.2	27.4	36.4	4.1	
I	1.690	35.2	26.5	38.3	2.9	
I	1.712	35.1	29.9	35.0	2.1	
I	1.760	33.9	30.0	36.1	1.9	
I	1.590	32.9	39.9	27.2	5.3	
I	1.754	32.8	32.3	34.8	2.6	
I	1.785	22.2	42.0	35.8	2.6

I	0.367	68.6	
I	0.387	63.6	
I	0.373	55.2	
I	0.377	74.6	

N	1.339	46.9	43.4	9.6	6.1	
N	1.437	45.6	41.4	13.0	4.8	
N	1.471	42.0	43.9	14.1	5.0	
N	1.641	36.1	27.0	36.9	4.0	
N	1.551	34.4	30.1	35.5	4.3	
N	1.673	33.7	39.0	27.3	2.1	
N	1.697	32.4	39.9	27.7	3.3	
N	1.713	32.1	33.6	34.3	1.4	
N	1.455	31.7	38.1	30.2	5.9	
N	1.524	27.5	27.8	44.7	4.7	
N	1.501	20.5	29.3	50.2	5.5	
N	1.687	19.1	18.0	62.8	3.3	
N	1.693	15.6	16.4	68.0	1.7	
N	1.614	11.1	17.6	71.3	2.6	
Z	1.427	24.4	52.9	22.7	8.3	
Z	1.524	24.2	50.6	25.2	5.5	
Z	1.456	23.8	50.0	26.2	7.6	
Z	1.550	23.0	54.6	22.4	5.8	
Z	1.543	22.1	55.1	22.8	5.6	
Z	1.471	21.2	50.5	28.3	6.0	
Z	1.543	23.0	52.5	24.6	5.8	
H	1.514	22.0	29.9	48.1	2.2	
H	1.449	18.9	38.3	42.8	3.1	
R	1.500	59.3	35.3	5.3	3.3	
R	1.509	53.3	36.0	10.7	1.5	
R	1.402	44.3	51.5	4.2	1.1	
R	1.629	39.1	42.9	18.0	2.2	
R	1.406	37.2	58.8	4.0	3.0	
R	1.545	37.0	49.5	13.5	2.5	
R	1.692	30.2	37.5	32.3	1.6	
R	1.554	28.0	43.9	28.0	3.6	
R	1.420	22.4	31.5	46.1	8.2	
R	1.451	22.2	33.1	44.7	5.6	
R	1.590	21.3	29.1	49.6	4.1	
R	1.541	21.3	51.4	27.3	2.3	
R	1.488	20.0	34.0	46.0	6.5	
R	1.345	15.4	41.1	43.6	7.0	
M	1.236	54.7	36.5	8.9	4.1	
M	1.432	54.4	35.2	10.5	5.6	
M	1.482	51.2	40.3	8.5	2.8	
M	1.465	42.0	41.1	16.9	3.4	
M	1.461	38.2	30.0	31.7	4.5	
M	1.523	34.3	46.2	19.5	0.0	
M	1.696	27.1	33.0	39.9	2.9	
M	1.747	26.6	33.8	39.5	2.8	
M	1.656	26.6	36.1	37.3	3.3	
M	1.691	26.5	36.0	37.5	2.6	
M	1.429	26.3	39.3	34.4	6.0	
M	1.750	25.8	29.2	45.1	2.4	
M	1.817	25.2	34.9	39.9	0.0	
M	1.753	25.2	38.6	36.2	2.4	
M	1.710	24.3	33.4	42.4	2.5	
M	1.675	23.6	33.2	43.1	3.1	
M	1.576	23.2	33.3	43.5	4.2	
M	1.642	23.2	38.3	38.5	3.4	
M	1.669	23.2	32.1	44.7	3.4	
M	1.693	23.1	31.5	45.5	3.1	
M	1.436	19.2	19.1	61.6	8.1	
M	1.669	12.6	20.1	67.3	3.4	
M	1.641	12.3	18.6	69.1	1.6	
M	1.605	12.2	10.1	77.7	1.9	
M	1.591	11.8	12.5	75.7	1.5	
M	1.514	9.5	12.2	78.3	4.5	
M	1.556	6.4	6.6	86.9	1.0	
C	1.429	63.4	31.3	5.3	3.4	
C	1.394	59.9	32.4	7.7	2.1	
C	1.359	59.5	33.3	7.2	3.3	
C	1.312	57.4	37.2	5.4	5.0	
C	1.311	57.4	34.6	8.0	5.0	
C	1.369	52.8	41.4	5.8	4.9	
C	1.519	52.5	30.8	16.8	3.4	
C	1.366	52.0	40.0	8.0	4.3	
C	1.403	49.2	42.8	8.0	5.0	
C	1.411	48.4	27.6	24.0	5.5	
C	1.539	50.1	36.4	13.5	1.7	
C	1.407	44.8	49.9	5.2	2.6	
C	1.559	44.3	31.1	24.6	2.8	
C	1.588	40.5	37.2	22.3	0.0	
C	1.574	40.1	41.9	18.0	2.0	
C	1.614	37.3	41.5	21.2	2.2	
C	1.712	32.3	31.5	36.2	1.8	
C	1.500	30.7	40.6	28.7	3.8	
C	1.420	22.3	42.6	35.1	5.0

C	0.590	36.3	

S	1.379	28.6	54.4	17.0	3.4	
S	1.436	25.7	53.1	21.2	3.5	
S	1.433	22.7	40.0	37.3	4.5	
S	1.472	21.0	39.0	40.1	4.5	
AC	1.385	22.3	58.6	19.0	3.4	
AC	1.340	18.7	70.4	10.9	4.7	
AC	1.347	17.9	70.6	11.5	4.8	
AC	1.218	10.4	75.7	13.9	4.8	
AC	1.380	9.8	72.5	17.7	3.8	
AC	1.410	9.8	74.2	16.0	3.0	
AC	1.202	8.5	66.9	24.6	7.1	
AC	1.423	7.3	13.7	79.0	2.0	
AC	1.308	6.2	64.6	29.2	3.8	
AC	1.294	5.0	61.1	33.9	4.0	
AC	1.344	4.7	67.9	27.4	2.9	
AC	1.268	4.5	62.4	33.1	4.5	
Y	1.278	28.4	67.5	4.1	5.6	
U	1.407	3.6	39.5	56.8	2.2	
O	1.433	38.8	44.4	16.8	4.5	
P	1.167	51.4	38.4	10.2	12.2	
P	1.263	49.9	44.9	5.2	8.3	
P	1.201	42.9	49.2	7.9	10.7	
P	1.458	39.8	49.3	10.9	5.0	
P	1.402	37.2	48.2	14.5	5.0	
P	1.266	36.8	53.8	9.4	7.2	
P	1.472	35.7	54.6	9.7	3.1	
P	1.470	33.6	26.1	40.3	5.2	
P	1.485	31.3	27.0	41.7	5.3	
P	1.436	31.2	44.4	24.4	5.3	
P	1.480	29.7	47.9	22.4	4.1	
P	1.379	28.4	31.4	40.1	7.4	
P	1.418	27.9	50.1	22.0	5.3	
P	1.429	27.2	53.4	19.5	5.2	
P	1.458	27.0	49.4	23.6	5.0	
P	1.448	25.6	40.5	33.9	5.3	
P	1.639	23.4	48.7	27.9	2.0	
P	1.461	21.8	45.7	32.5	6.6	
P	1.584	21.5	41.3	37.1	4.5	
P	1.563	20.0	39.9	40.2	4.7	
P	1.501	12.9	25.5	61.6	4.6	
P	1.461	10.6	17.2	72.2	6.2	
T	1.203	56.5	31.1	12.4	11.3	
T	1.416	33.7	50.6	15.7	4.5	
T	1.521	30.2	55.5	14.3	3.5	
T	1.581	17.1	60.1	22.8	2.1	
E	1.356	69.7	24.3	6.0	4.0	
E	1.300	65.0	26.4	8.6	4.7	
E	1.380	58.5	23.4	18.1	4.0	
E	1.419	55.3	24.7	20.0	4.1	
E	1.483	52.0	32.8	15.2	3.2	
E	1.603	43.8	38.0	18.2	1.8	
E	1.504	42.0	42.4	15.7	4.5	
E	1.601	38.9	42.4	18.6	2.0	
E	1.514	37.1	37.5	25.4	5.5	
E	1.531	34.3	34.4	31.3	3.5	
E	1.498	29.6	59.9	10.5	3.9	
E	1.735	27.6	48.1	24.3	1.8	
E	1.613	27.4	24.1	48.5	3.1	
E	1.681	24.3	21.6	54.1	2.3	
E	1.647	24.3	51.7	24.0	2.4	
E	1.654	14.1	50.2	35.7	2.0	
E	1.646	13.1	18.2	68.7	2.6	
E	1.599	11.8	18.7	69.5	2.8	
SFb	0.803	83.3	14.6	2.1	31.2	
SFb	1.598	21.0	22.2	56.9	4.1	
SFb	1.156	77.3	17.8	4.9	10.0	
PLc	1.621	7.3	71.0	21.7	1.5	
PLc	1.788	16.9	34.6	48.5	1.2	
---END refdata.txt---

omdata.txt   - high Organic matter data from Keller and Håkansson
---BEGIN omdata.txt---
#ref_den	OM	
0.803	31.2	
0.590	36.3	
0.373	55.2	
0.387	63.6	
0.367	68.6	
0.377	74.6	
0.376	100.0	
---END omdata.txt---

testdata.txt - data file created to show results of using equation from Keller and Håkansson with special function for high organic matter soils.
---BEGIN testdata.txt---
 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 S         1.55499995       1.52629995       1.60805988       0.00000000    
 S         1.19882989       1.16629994       1.32130980       5.00000007E-02
 S        0.975413084      0.806300044       1.03455973      0.100000001    
 S        0.822188139      0.446299940      0.747809887      0.150000006    
 S        0.710567057       8.63000378E-02  0.461059809      0.200000003    
 S        0.625630915     -0.273699969      0.174309850      0.250000000    
 S        0.558832049     -0.633700132      0.892163754      0.300000012    
 S        0.504921377     -0.993700027      0.621218622      0.349999994    
 S        0.460497081      -1.35369992      0.503045321      0.400000006    
 S        0.423257798      -1.71369982      0.446712971      0.449999988    
 S        0.391590804      -2.07369995      0.416464984      0.500000000    
 S        0.364332408      -2.43370008      0.398590088      0.550000012    
 S        0.340621918      -2.79370022      0.387223542      0.600000024    
 S        0.319809020      -3.15369987      0.379574567      0.649999976    
 S        0.301393092      -3.51370001      0.374192506      0.699999988    
 S        0.284982622      -3.87369967      0.370267153      0.750000000    
 S        0.270266920      -4.23369980      0.367318839      0.800000012    
 S        0.256996334      -4.59369993      0.365049452      0.850000024    
 S        0.244968012      -4.95369959      0.363266170      0.899999976    
 S        0.234015256      -5.31369972      0.361839801      0.949999988    
 S        0.224000022      -5.67369986      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 LS        1.55199993       1.50969994       1.66677999       0.00000000    
 LS        1.19713509       1.14969993       1.38472998       5.00000007E-02
 LS       0.974349797      0.789700031       1.10268009      0.100000001    
 LS       0.821474433      0.429699928      0.820629954      0.150000006    
 LS       0.710065365       6.97000399E-02  0.538580000      0.200000003    
 LS       0.625266254     -0.290299982      0.256530046      0.250000000    
 LS       0.558560431     -0.650300145      0.892163754      0.300000012    
 LS       0.504715502      -1.01030004      0.621218622      0.349999994    
 LS       0.460338980      -1.37029994      0.503045321      0.400000006    
 LS       0.423135370      -1.73029983      0.446712971      0.449999988    
 LS       0.391495526      -2.09029984      0.416464984      0.500000000    
 LS       0.364258170      -2.45029998      0.398590088      0.550000012    
 LS       0.340564251      -2.81030011      0.387223542      0.600000024    
 LS       0.319764555      -3.17029977      0.379574567      0.649999976    
 LS       0.301359236      -3.53029990      0.374192506      0.699999988    
 LS       0.284957379      -3.89029932      0.370267153      0.750000000    
 LS       0.270248771      -4.25029945      0.367318839      0.800000012    
 LS       0.256984025      -4.61029959      0.365049452      0.850000024    
 LS       0.244960532      -4.97029924      0.363266170      0.899999976    
 LS       0.234011859      -5.33029938      0.361839801      0.949999988    
 LS       0.224000022      -5.69029951      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 SL        1.55700004       1.47669995       1.74861991       0.00000000    
 SL        1.19995880       1.11669993       1.48246992       5.00000007E-02
 SL       0.976121008      0.756700039       1.21631992      0.100000001    
 SL       0.822663069      0.396699935      0.950169921      0.150000006    
 SL       0.710900903       3.67000364E-02  0.684019864      0.200000003    
 SL       0.625873506     -0.323299974      0.417869925      0.250000000    
 SL       0.559012651     -0.683300078      0.892163754      0.300000012    
 SL       0.505058289      -1.04330003      0.621218622      0.349999994    
 SL       0.460602194      -1.40329993      0.503045321      0.400000006    
 SL       0.423339218      -1.76329982      0.446712971      0.449999988    
 SL       0.391654164      -2.12329984      0.416464984      0.500000000    
 SL       0.364381790      -2.48329997      0.398590088      0.550000012    
 SL       0.340660274      -2.84330010      0.387223542      0.600000024    
 SL       0.319838613      -3.20329976      0.379574567      0.649999976    
 SL       0.301415622      -3.56329989      0.374192506      0.699999988    
 SL       0.284999400      -3.92329931      0.370267153      0.750000000    
 SL       0.270278990      -4.28329945      0.367318839      0.800000012    
 SL       0.257004529      -4.64329958      0.365049452      0.850000024    
 SL       0.244972959      -5.00329924      0.363266170      0.899999976    
 SL       0.234017521      -5.36329937      0.361839801      0.949999988    
 SL       0.224000022      -5.72329950      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 L         1.43200016       1.43400002       1.75169992       0.00000000    
 L         1.12787640       1.07400000       1.50364995       5.00000007E-02
 L        0.930301726      0.713999987       1.25559998      0.100000001    
 L        0.791628897      0.353999913       1.00755000      0.150000006    
 L        0.688934743      -5.99996373E-03  0.759499967      0.200000003    
 L        0.609825134     -0.365999997      0.511449993      0.250000000    
 L        0.547012269     -0.726000130      0.892163754      0.300000012    
 L        0.495930791      -1.08599997      0.621218622      0.349999994    
 L        0.453574687      -1.44599986      0.503045321      0.400000006    
 L        0.417884320      -1.80599976      0.446712971      0.449999988    
 L        0.387401015      -2.16599989      0.416464984      0.500000000    
 L        0.361062616      -2.52600002      0.398590088      0.550000012    
 L        0.338077575      -2.88600016      0.387223542      0.600000024    
 L        0.317843854      -3.24599981      0.379574567      0.649999976    
 L        0.299895316      -3.60599995      0.374192506      0.699999988    
 L        0.283865482      -3.96599936      0.370267153      0.750000000    
 L        0.269462377      -4.32599926      0.367318839      0.800000012    
 L        0.256450266      -4.68599939      0.365049452      0.850000024    
 L        0.244636983      -5.04599905      0.363266170      0.899999976    
 L        0.233864099      -5.40599918      0.361839801      0.949999988    
 L        0.224000022      -5.76599932      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 SiL       1.21520007       1.41250002       1.61330009       0.00000000    
 SiL      0.995046139       1.05250001       1.34675014       5.00000007E-02
 SiL      0.842426360      0.692499995       1.08020020      0.100000001    
 SiL      0.730398178      0.332499921      0.813650012      0.150000006    
 SiL      0.644668460      -2.74999626E-02  0.547100067      0.200000003    
 SiL      0.576949596     -0.387499988      0.280550092      0.250000000    
 SiL      0.522105277     -0.747500122      0.892163754      0.300000012    
 SiL      0.476782799      -1.10749996      0.621218622      0.349999994    
 SiL      0.438700348      -1.46749985      0.503045321      0.400000006    
 SiL      0.406251550      -1.82749975      0.446712971      0.449999988    
 SiL      0.378272384      -2.18749976      0.416464984      0.500000000    
 SiL      0.353898823      -2.54749990      0.398590088      0.550000012    
 SiL      0.332476079      -2.90750003      0.387223542      0.600000024    
 SiL      0.313498884      -3.26749969      0.379574567      0.649999976    
 SiL      0.296571106      -3.62749982      0.374192506      0.699999988    
 SiL      0.281377733      -3.98749948      0.370267153      0.750000000    
 SiL      0.267665207      -4.34749985      0.367318839      0.800000012    
 SiL      0.255227089      -4.70749998      0.365049452      0.850000024    
 SiL      0.243893623      -5.06749964      0.363266170      0.899999976    
 SiL      0.233523920      -5.42749977      0.361839801      0.949999988    
 SiL      0.224000022      -5.78749990      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 SCL       1.62569988       1.45029998       1.82869995       0.00000000    
 SCL       1.23827052       1.09029996       1.61154997       5.00000007E-02
 SCL      0.999963760      0.730300009       1.39440000      0.100000001    
 SCL      0.838578224      0.370299935       1.17724991      0.150000006    
 SCL      0.722046196       1.03000402E-02  0.960099876      0.200000003    
 SCL      0.633950114     -0.349699974      0.742949903      0.250000000    
 SCL      0.565013409     -0.709700108      0.892163754      0.300000012    
 SCL      0.509598851      -1.06970000      0.621218622      0.349999994    
 SCL      0.464083195      -1.42969990      0.503045321      0.400000006    
 SCL      0.426031500      -1.78969979      0.446712971      0.449999988    
 SCL      0.393746912      -2.14969969      0.416464984      0.500000000    
 SCL      0.366010636      -2.50969982      0.398590088      0.550000012    
 SCL      0.341924846      -2.86969995      0.387223542      0.600000024    
 SCL      0.320813328      -3.22969961      0.379574567      0.649999976    
 SCL      0.302157193      -3.58969975      0.374192506      0.699999988    
 SCL      0.285551578      -3.94969940      0.370267153      0.750000000    
 SCL      0.270676106      -4.30969954      0.367318839      0.800000012    
 SCL      0.257273704      -4.66969967      0.365049452      0.850000024    
 SCL      0.245135948      -5.02969933      0.363266170      0.899999976    
 SCL      0.234091863      -5.38969946      0.361839801      0.949999988    
 SCL      0.224000022      -5.74969959      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 CL        1.44389999       1.40330005       1.75746000       0.00000000    
 CL        1.13487470       1.04329991       1.55471003       5.00000007E-02
 CL       0.934806228      0.683299959       1.35196006      0.100000001    
 CL       0.794706404      0.323299944       1.14921010      0.150000006    
 CL       0.691127002      -3.66999544E-02  0.946460009      0.200000003    
 CL       0.611434579     -0.396699965      0.743710160      0.250000000    
 CL       0.548220396     -0.756700158      0.892163754      0.300000012    
 CL       0.496852547      -1.11669993      0.621218622      0.349999994    
 CL       0.454286188      -1.47669983      0.503045321      0.400000006    
 CL       0.418437809      -1.83669972      0.446712971      0.449999988    
 CL       0.387833357      -2.19669986      0.416464984      0.500000000    
 CL       0.361400545      -2.55669999      0.398590088      0.550000012    
 CL       0.338340908      -2.91670012      0.387223542      0.600000024    
 CL       0.318047494      -3.27669978      0.379574567      0.649999976    
 CL       0.300050676      -3.63669991      0.374192506      0.699999988    
 CL       0.283981472      -3.99669957      0.370267153      0.750000000    
 CL       0.269545972      -4.35669994      0.367318839      0.800000012    
 CL       0.256507069      -4.71670008      0.365049452      0.850000024    
 CL       0.244671434      -5.07669973      0.363266170      0.899999976    
 CL       0.233879849      -5.43669987      0.361839801      0.949999988    
 CL       0.224000022      -5.79670000      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 SiCL      1.39080000       1.37250006       1.60829997       0.00000000    
 SiCL      1.10341859       1.01249993       1.40225005       5.00000007E-02
 SiCL     0.914462805      0.652499974       1.19620001      0.100000001    
 SiCL     0.780760825      0.292499930      0.990149975      0.150000006    
 SiCL     0.681168377      -6.74999580E-02  0.784099996      0.200000003    
 SiCL     0.604109406     -0.427499980      0.578050077      0.250000000    
 SiCL     0.542713404     -0.787500143      0.892163754      0.300000012    
 SiCL     0.492645621      -1.14749992      0.621218622      0.349999994    
 SiCL     0.451035440      -1.50749981      0.503045321      0.400000006    
 SiCL     0.415906876      -1.86749971      0.446712971      0.449999988    
 SiCL     0.385854840      -2.22749996      0.416464984      0.500000000    
 SiCL     0.359853089      -2.58750010      0.398590088      0.550000012    
 SiCL     0.337134421      -2.94750023      0.387223542      0.600000024    
 SiCL     0.317114085      -3.30749989      0.379574567      0.649999976    
 SiCL     0.299338192      -3.66750002      0.374192506      0.699999988    
 SiCL     0.283449382      -4.02749968      0.370267153      0.750000000    
 SiCL     0.269162297      -4.38749981      0.367318839      0.800000012    
 SiCL     0.256246358      -4.74749994      0.365049452      0.850000024    
 SiCL     0.244513243      -5.10749960      0.363266170      0.899999976    
 SiCL     0.233807549      -5.46749973      0.361839801      0.949999988    
 SiCL     0.224000022      -5.82749987      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 SC        1.61899996       1.42219996       1.81718016       0.00000000    
 SC        1.23457360       1.06219995       1.63913012       5.00000007E-02
 SC       0.997678101      0.702199996       1.46108007      0.100000001    
 SC       0.837059438      0.342199951       1.28303003      0.150000006    
 SC       0.720986068      -1.77999660E-02   1.10497999      0.200000003    
 SC       0.633183777     -0.377799958      0.926930070      0.250000000    
 SC       0.564445138     -0.737800121      0.892163754      0.300000012    
 SC       0.509169519      -1.09780002      0.621218622      0.349999994    
 SC       0.463754475      -1.45779991      0.503045321      0.400000006    
 SC       0.425777495      -1.81779981      0.446712971      0.449999988    
 SC       0.393549681      -2.17779994      0.416464984      0.500000000    
 SC       0.365857273      -2.53780007      0.398590088      0.550000012    
 SC       0.341805845      -2.89780021      0.387223542      0.600000024    
 SC       0.320721656      -3.25779986      0.379574567      0.649999976    
 SC       0.302087486      -3.61780000      0.374192506      0.699999988    
 SC       0.285499722      -3.97779965      0.370267153      0.750000000    
 SC       0.270638824      -4.33779955      0.367318839      0.800000012    
 SC       0.257248461      -4.69779968      0.365049452      0.850000024    
 SC       0.245120645      -5.05779934      0.363266170      0.899999976    
 SC       0.234084889      -5.41779947      0.361839801      0.949999988    
 SC       0.224000022      -5.77779961      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 SiC       1.42400002       1.35129988       1.54718006       0.00000000    
 SiC       1.12315500      0.991299987       1.37773001       5.00000007E-02
 SiC      0.927255809      0.631300032       1.20827997      0.100000001    
 SiC      0.789544582      0.271299928       1.03883004      0.150000006    
 SiC      0.687448263      -8.86999518E-02  0.869380057      0.200000003    
 SiC      0.608732879     -0.448699981      0.699930012      0.250000000    
 SiC      0.546191812     -0.808700085      0.892163754      0.300000012    
 SiC      0.495304406      -1.16870010      0.621218622      0.349999994    
 SiC      0.453090876      -1.52869999      0.503045321      0.400000006    
 SiC      0.417507857      -1.88869989      0.446712971      0.449999988    
 SiC      0.387106836      -2.24869990      0.416464984      0.500000000    
 SiC      0.360832602      -2.60870004      0.398590088      0.550000012    
 SiC      0.337898314      -2.96870017      0.387223542      0.600000024    
 SiC      0.317705184      -3.32869983      0.379574567      0.649999976    
 SiC      0.299789518      -3.68869996      0.374192506      0.699999988    
 SiC      0.283786476      -4.04869938      0.370267153      0.750000000    
 SiC      0.269405395      -4.40869951      0.367318839      0.800000012    
 SiC      0.256411552      -4.76869965      0.365049452      0.850000024    
 SiC      0.244613498      -5.12869930      0.363266170      0.899999976    
 SiC      0.233853385      -5.48869944      0.361839801      0.949999988    
 SiC      0.224000022      -5.84869957      0.360681325       1.00000000    


 #Texture Settled_Bulk_Den Normal_Bulk_den Reference_Bulk_Den OM_frac
 C         1.36100006       1.34070003       1.48048007       0.00000000    
 C         1.08550477      0.980699956       1.37468004       5.00000007E-02
 C        0.902765810      0.620700002       1.26888013      0.100000001    
 C        0.772687912      0.260699958       1.16308010      0.150000006    
 C        0.675374389      -9.92999524E-02   1.05728006      0.200000003    
 C        0.599830866     -0.459299952      0.951480091      0.250000000    
 C        0.539486825     -0.819300115      0.892163754      0.300000012    
 C        0.490174502      -1.17929995      0.621218622      0.349999994    
 C        0.449121982      -1.53929985      0.503045321      0.400000006    
 C        0.414414495      -1.89929974      0.446712971      0.449999988    
 C        0.384686440      -2.25929999      0.416464984      0.500000000    
 C        0.358938038      -2.61930013      0.398590088      0.550000012    
 C        0.336420238      -2.97930026      0.387223542      0.600000024    
 C        0.316560954      -3.33929992      0.379574567      0.649999976    
 C        0.298915595      -3.69930005      0.374192506      0.699999988    
 C        0.283133507      -4.05929947      0.370267153      0.750000000    
 C        0.268934369      -4.41929960      0.367318839      0.800000012    
 C        0.256091386      -4.77929974      0.365049452      0.850000024    
 C        0.244419158      -5.13929939      0.363266170      0.899999976    
 C        0.233764514      -5.49929953      0.361839801      0.949999988    
 C        0.224000022      -5.85929966      0.360681325       1.00000000    
---END testdata.txt---

proctor-wepp.txt - from Wagner et al. 1994
---BEGIN proctor-wepp.txt---
#Soil_Series	-	Clay	Sand	OM	OWC	MDD	coef	coef
#Name	NSSLID	(%)	(%)	(%)	(%)g/g	(Mg/m3)	K1	Kb
Mexico	89p1135s	22.1	4.6	1.55	19.5	1.58	0.0156	-0.0240
Tifton	89p1136s	4.7	86.5	0.43	8.0	1.91	0.0100	-0.0270
Bonifay	89p1137s	3.7	91.9	0.25	10.0	1.77	0.0023	-0.0165
Cecil	89p1139s	33.6	51.8	0.66	17.5	1.73	0.0393	-0.0249
Opequon	89p1141s	32.9	12.1	1.50	21.0	1.55	0.0201	-0.0163
Fredrick	89p1142s	16.8	22.0	1.23	18.5	1.59	0.0196	-0.0140
Manor	89p1143s	24.6	44.2	0.97	19.5	1.65	0.0216	-0.0140
Caribou	89p1144s	14.2	46.0	1.84	20.0	1.60	0.0142	-0.0280
Collamer	89p1145s	17.0	4.8	1.06	18.0	1.65	0.0194	-0.0228
Miamian	89p1146s	30.5	30.4	2.01	19.0	1.65	0.0065	-0.0220
Miami	89p1148s	15.9	4.4	0.79	18.0	1.68	0.0108	-0.0261
Grenada	89p1149s	20.4	3.5	0.99	17.5	1.65	0.0093	-0.0282
Acadamy	89p962s	13.6	63.0	0.34	13.0	1.93	0.0381	-0.0308
Los_Banos	89p964s	49.4	15.7	1.45	23.5	1.53	0.0046	-0.0147
Whitney	89p966s	6.7	75.0	0.27	10.0	1.99	0.0175	-0.0401
Sverdrup	89p970s	22.6	46.9	1.54	15.5	1.67	0.0145	-0.0093
Amarillo	89p972s	7.5	86.5	0.14	9.0	1.92	0.0190	-0.0240
Barnes	89p974s	25.3	42.4	2.52	20.5	1.59	0.0155	-0.0218
Williams	89p976s	26.9	41.8	1.61	15.0	1.79	0.0166	-0.0240
Pierre	89p978s	48.7	11.5	1.35	26.0	1.47	0.0129	-0.0171
Palouse	89p980s	22.1	8.3	1.35	18.0	1.65	0.0116	-0.0207
Woodward	89p984s	12.0	48.5	0.75	12.5	1.79	0.0140	-0.0289
Zahl	89p986s	29.8	46.4	1.70	17.0	1.67	0.0204	-0.0166
Sharpsburg	89p990s	41.0	2.4	1.70	23.5	1.48	0.0040	-0.0127
Portneuf	89p994s	9.7	16.1	0.77	20.5	1.53	0.0072	-0.0280
Keith	89p996s	17.8	47.3	0.94	18.5	1.63	0.0144	-0.0447
Inavale	91z349s	5.0	85.1	0.42	10.0	1.92	0.0162	-0.0401
Harney	91z350s	30.5	12.3	1.00	18.5	1.64	0.0237	-0.0219
Fargo	91z351s	47.4	12.1	3.13	26.0	1.46	0.0057	-0.0147
Smolan	91z352s	32.3	9.1	1.35	19.0	1.65	0.0117	-0.0221
Richfield	91z353s	26.2	28.9	0.97	18.0	1.68	0.0176	-0.0280
Lincoln	91z354s	15.8	58.1	1.04	12.5	1.82	0.0237	-0.0240
Dalhart	91z355s	7.5	75.1	0.68	9.0	1.83	0.0301	-0.0312
Reading	91z356s	25.1	7.2	1.50	18.5	1.63	0.0087	-0.0223
New_Cambria	91z357s	42.4	12.7	1.91	22.0	1.57	0.0120	-0.0223
Santanta	91z358s	8.5	71.5	0.77	11.0	1.90	0.0176	-0.0401
Carr	91z359s	3.6	74.7	0.47	16.0	1.63	0.0074	-0.0325
Wymore	91z360s	25.2	10.5	1.31	17.0	1.67	0.0122	-0.0210
Hanie	91z361s	5.9	61.4	0.64	15.5	1.64	0.0141	-0.0243
---BEGIN proctor-wepp.txt---

proctor-serdp.txt - from SERDP project data
---BEGIN proctor-SERDP.txt---
#Sample-ID	Clay	Silt	Sand	OM	OWC	PD (g/cm3)
FR-SL-R3-WH-PO-05	18.62686778	71.75965353	9.613478692	3.404360605	20.11338844	1.56274184
FR-SL-R2-WH-PO-05	20.98327876	69.79967466	9.217046581	3.849268234	19.63813553	1.697922485
FR-SL-R1-TR-PO-05	12.92465037	76.01859816	11.05675147	3.984674904	22.03985834	1.55242871
FR-SL-R2-TR-PO-05	22.14278258	67.35176648	10.50545094	3.636486324	19.2904005	1.713382669
FR-SL-R1-WH-PO-05	25.47354521	65.25427134	9.27218345	4.120081574	21.38949605	1.534399862
FR-SL-R3-TR-PO-05	14.06435799	74.13623198	11.79941003	4.990553023	20.45053004	1.560581219
FR-SCL-R1-WH-PO-05	27.64629737	66.55232603	5.801376598	4.004018714	26.03644236	1.475909681
FR-SCL-R1-TR-PO-05	28.13549339	62.38346868	9.481037924	3.365672985	22.89623628	1.575276597
FR-SCL-R2-TR-PO-05	30.82098293	61.2378406	7.941176471	3.887955854	23.51197216	1.630267221
FR-SCL-R3-TR-PO-05	17.15781284	74.3417096	8.500477555	4.855146353	22.93827367	1.483344311
FR-SCL-R2-WH-PO-05	31.53102317	60.04479448	8.424182359	4.564989203	22.22120093	1.436441982
FR-SCL-R3-WH-PO-05	32.87030437	59.99382075	7.135874878	3.887955854	23.52755564	1.478180526
FB-1	2.474101275	11.77596112	85.74993761	0.904728445	7.769315014	1.809983549
FB-2	4.138304349	10.54334359	85.31835206	0.791580557	8.930836425	1.890452977
FB-3	3.828647365	10.38936211	85.78199052	1.221542531	8.953377399	1.866578099
FB-4	1.872292857	6.837465067	91.29024208	0.316359428	8.431488191	1.761330138
FB-5	2.572194121	8.644393438	88.78341244	1.085765066	8.842268466	1.779985598
FB-6	1.711608728	9.055316079	89.23307519	0.836839712	8.511624485	1.794777459
Y-1	3.556197911	42.54769819	53.8961039	1.69676366	16.13333648	1.656218882
Y-2	4.104508264	48.71344685	47.18204489	2.239873522	17.49970668	1.630526876
Y-3	5.601967677	46.34608427	48.05194805	1.493097462	16.89095274	1.663668865
Y-4	5.148246534	44.45175347	50.4	2.217243945	16.0434848	1.693399254
Y-5	5.080669806	41.02711463	53.89221557	1.990948169	17.94439506	1.599544887
Y-6	6.200861996	39.649138	54.15	2.760353807	17.56967804	1.642219248
WS-1-CI-5	20.79013735	57.17088214	22.03898051	2.9	19.84116879	1.632309257
WS-2-CI-5	19.87640236	44.27359764	35.85	2.3	19.61012473	1.644122608
WS-3-CI-5	18.21068644	38.98931356	42.8	2.2	16.38196065	1.690257536
WS-4-CI-5	25.68832575	35.80018574	38.51148851	1.1	16.36673026	1.734720037
WS-5-CI-5	19.91163429	29.08936471	50.999001	1.3	19.85413649	1.632602876
WS-6-CI-5	26.74627926	32.98425966	40.26946108	1	18.14613609	1.702832621
WS-7-CI-5	8.604297395	23.39570261	68	1	9.025867225	1.93447718
WS-8-CI-5	9.078936478	19.60672069	71.31434283	0.9	8.83704392	1.948801828
WS-9-CI-5	8.686061989	23.96393801	67.35	0.6	8.581776334	1.955855893
WS-10-CI-5	6.397861503	16.57916147	77.02297702	0.7	8.444046221	1.942351566
WS-11-CI-5	7.111618178	16.88838182	76	0.8	8.994483817	1.940915367
WS-12-CI-5	6.238977719	15.42852103	78.33250125	0.8	9.800388524	1.934803049
---END proctor-SERDP.txt---

---BEGIN show_all_data.plt---
set xrange [0:1]
set term pdf size 29.7cm,21cm
set output 'all_data.pdf'
set ylabel 'Bulk Density (Mg/m^3)'
set key top
set xlabel 'Organic Matter (fraction)'
plot 'proc-wepp-ref.txt' using 11:3 with points title 'Wagner, 1994 (Proctor)', 'proc-serdp-ref.txt' using 11:3 with points title 'GA, KS, NM, WA (Proctor)', 'proc-pref-ref.txt' using 11:3 with points title 'Keller and Håkansson, 2010 (Uni-axial)'
set key bottom
set xlabel 'Sand (fraction)'
plot 'proc-wepp-ref.txt' using 10:3 with points title 'Wagner, 1994 (Proctor)', 'proc-serdp-ref.txt' using 10:3 with points title 'GA, KS, NM, WA (Proctor)', 'proc-pref-ref.txt' using ($11<0.35?($10):NaN):3 with points title 'Keller and Håkansson, 2010 (Uni-axial)'
set xlabel 'Silt (fraction)'
plot 'proc-wepp-ref.txt' using 9:3 with points title 'Wagner, 1994 (Proctor)', 'proc-serdp-ref.txt' using 9:3 with points title 'GA, KS, NM, WA (Proctor)', 'proc-pref-ref.txt' using ($11<0.35?($9):NaN):3 with points title 'Keller and Håkansson, 2010 (Uni-axial)'
set xlabel 'Clay (fraction)'
plot 'proc-wepp-ref.txt' using 8:3 with points title 'Wagner, 1994 (Proctor)', 'proc-serdp-ref.txt' using 8:3 with points title 'GA, KS, NM, WA (Proctor)', 'proc-pref-ref.txt' using ($11<0.35?($8):NaN):3 with points title 'Keller and Håkansson, 2010 (Uni-axial)'
---END show_all_data.plt---

Physical characteristics of organic soils (http://www.fao.org/docrep/003/y1899e/y1899e04.htm)

Fibric Histosols are loosely packed in their natural state, with a bulk density (_) that is typically between 0.05 and 0.15 Mg/m3. Surface tiers of ombrogenous forest peat contain (still) more mineral `ash' than the subsurface layers and are slightly denser (_ -values of the order of 0.15 to 0.25 Mg/m3). Reclaimed (drained and cropped) peat formations acquire a higher bulk density (say, 0.4 Mg/m3) after a few years of consolidation and decomposition of peat.

The specific gravity (_s) of organic soil material with a low content of mineral constituents (less than, say, 3 percent by weight) is nearly always close to 1.4 Mg/m3. It follows that the total pore fraction (= 1-_ /_s) of most ombrogenous Fibric Histosols exceeds 0.9 m3/m3; skeletal subsurface tiers consist for only 5 to 10 volume percent of solid matter (sic!).

Fibric peat has many wide pores. Its saturated hydraulic conductivity is typically greater than 1.6 m/d and may well exceed 30 m/d. Well-decomposed sapric peat has finer pores and is less permeable. Virgin woody peat is nearly always very permeable to water; compacted (reclaimed/drained) peat has a much lower Total Pore Fraction than virgin peat. Compacted, stratified peat may be virtually impermeable, irrespective of its fiber content.